CN100369136C - Optical head device and optical disk device - Google Patents

Optical head device and optical disk device Download PDF

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Publication number
CN100369136C
CN100369136C CNB03104462XA CN03104462A CN100369136C CN 100369136 C CN100369136 C CN 100369136C CN B03104462X A CNB03104462X A CN B03104462XA CN 03104462 A CN03104462 A CN 03104462A CN 100369136 C CN100369136 C CN 100369136C
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China
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light
lens
diffraction
information
information medium
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CN1516141A (en
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金马庆明
水野定夫
西野清治
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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  • Holo Graphy (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

A compound objective lens is composed of a hologram lens for transmitting a part of incident light without any diffraction to form a beam of transmitted light and diffracting a remaining part of the incident light to form a beam of first-order diffracted light, and an objective lens for converging the transmitted light to form a first converging spot on a front surface of a thin type of first information medium and converging the diffracted light to form a second converging spot on a front surface of a thick type of second information medium. Because the hologram lens selectively functions as a concave lens for the diffracted light, a curvature of the transmitted light differs from that of the diffracted light. Therefore, even though the first and second information mediums have different thicknesses, the transmitted light incident on a rear surface of the first information medium is converged on the its front surface, and the diffracted light incident on a rear surface of the second information medium is converged on the its front surface. That is, the compound objective lens has two focal points.

Description

Optic probe device and optical disc apparatus
The application is based on dividing an application of the application for a patent for invention 94103940.4 that is entitled as " complex objective lens with bifocal, imaging optical system and optical head device " that the applicant submits on April 1st, 1994.
Technical field
The present invention relates to a kind of optic probe device and optical disc apparatus.
Background technology
The present invention relates to a kind of by object lens and the complex objective lens that the hologram lens are formed with two focuses, a kind of with compound lens the imaging optical system of optical convergence to two focal points that are positioned at the information medium different depth, one with imaging optical system or from the information medium of the optical media as CD or light-card or magneto-optical media and so on record, optical head (optical head) device of reproduction or erasure information, a kind of a series of high density recording pits (pit) and a series of CD of wherein being provided with than low-density record pit, a kind of a series of degree record pits (pit) and a series of CD of wherein being provided with than low-density record pit, a kind of with complex objective lens or from the optical disc apparatus of CD record or reproduction information, a kind of bifocus microscope of wherein observing two kinds of images that are drawn on different depth simultaneously that two focuses are arranged, and a kind of two kinds of alignment devices that image is aimed at that are drawn on different depth with bifocus microscope handle.
The optical memory technology has been put to actual use so that make a kind of CD, and the pit pattern that a series of pits that wherein draw form is so that recorded information.CD is as high density high capacity information medium.For example, CD is as digital audio disc, video disc, archive files dish and data archival dish.For recorded information on the CD and from the CD reproduction information, the light beam from light emitted is assembled minimumly imaging optical system, and the light beam of assembling minimumly shines on the CD through imaging optical system.Thereby light beam need be controlled with very high precision in imaging optical system reliably.
Imaging optical system is used for the optical head device, wherein additionally detection system is set so that survey beam intensity from CD reflection.The basic function of optical head device is divided into, get beam convergence minimum so that form the optically focused performance of diffraction limited (diffraction-limited) the low-light point that is radiated at the light beam on the CD, focal point control in the focus servo system, tracking Control in the tracking servo, and the pit (or information signal) of detection by light beam irradiates is obtained on the pit pattern of CD.The basic function of optical head device depends on the combination according to purpose and purposes optical subsystem and opto-electronic conversion detection process.Exactly, propose a kind of optical head device recently, in this device, utilized a holographic optical elements (HOE) (or hologram) to dwindle and attenuate optical head device.
Fig. 1 is the structural drawing of the conventional optical head device that proposed in the Japanese patent application that proposed by the present inventor 1991 No. 46630.
As shown in fig. 1, a kind of or be provided with the light beam source 13 of semiconductor laser and so on from the conventional optical head device of information medium 12 record of CD and so on or reproduction information, one in emitting light path without any the transmission of diffraction ground from light beam source 13 emitted light beams L1 and during returning light path the transmission-type of the light beam L2 of diffraction reflection to the information medium worker 2 (blazed) the holographic Figure 14 that glitters, a handle converges on the information medium 12 so that the object lens of sense information 15 through the light beam L1 of holographic Figure 14 transmission, one is moved object lens 15 so that with object lens 15 light beam L1 is focused on actuator 16 on the information medium 12 together with blazed hologram 14 is whole, and the intensity of detection beam reflected L2 of institute on information medium 12 is so that reappear the photodetector 17 of information.
As shown in Fig. 2 A, the relative position between blazed hologram 14 and the object lens 15 is fixed by stationary installation 18.Perhaps as shown in Fig. 2 B, the figure that glitters can form on a side of object lens 15 so that integrally form the blazed hologram 14 of band object lens 15.
In above structure, 13 emitted light beams L1 (or laser beam) shine blazed hologram 14 from light beam source, and light beam L1 mainly through blazed hologram 14 in emitting light path without any the transmission of diffraction ground.Light beam L1 through blazed hologram 14 transmissions is called zero order diffracted light.After this, zero order diffracted light L1 is converged on the information medium 12 by object lens 15.In information medium 12, the information of being indicated by a series of figure pits is write down and reads by zero order diffracted light L1.After this, the light beam L2 that has information is along 15 reflections of back light road direction object lens and inject blazed hologram 14.In blazed hologram 14, light L2 is mainly diffracted.The light L2 of institute's diffraction is called first-order diffraction light.After this, first-order diffraction light L2 is received in the photodetector 17.
In photodetector 17, survey the intensity distributions of first-order diffraction light L2.Thereby, obtain a servosignal of adjusting object lens 15 positions with the action of actuator 16.In addition, in photodetector 17, survey the intensity of first-order diffraction light L2.Because information medium 12 high speed rotating, the figure pit that is shone by light L2 changes, so that the Strength Changes of the first-order diffraction light L2 that is detected.Thereby, obtain indicating the information signal that is recorded in information among the information medium L2 by the Strength Changes of surveying first-order diffraction light L2.
In above operation, the part of light beam L1 light beam L1 when emitting light path shines blazed hologram 14 inevitable in blazed hologram 14 diffraction.Thereby, certainly exist as the unnecessary diffraction light of first-order diffraction light and negative first-order diffraction light and so on.Under the situation that holographic Figure 14 does not glitter, the unnecessary diffraction light in the emitting light path is the information of playback record in information medium 12 also, and unnecessary diffraction light is undesirably taken in photodetector 17.In order to prevent unnecessary transmittance to information medium 12, blazed hologram is formed in its surface forms blazed hologram shape, thereby reduce the unnecessary light in the income photodetector 17.
In addition, because conventional microscopical object lens have only a focus, can only observe the image within the depth of focus that is in object lens with conventional microscope.
In addition, on the semiconductor of picture one group of III-V composite semiconductor and so on, form a small circuit, so that form a microwave circuit, photodetector or solid-state laser.In this case, on the exemplar that semiconductor is made, apply photochromics.Then, utilize alignment device to adjust relative position between exemplar and the photomask that covers exemplar, utilize exposure device in exposure-processed with exposing light beam by photomask to the photochromics exposure in case the circuitous pattern that handle is drawn on the photomask transfer on the photochromics.For example, adjust relative position between exemplar and the photomask during circuitous pattern accurately drawing alignment patterns on the rear side of exemplar at alignment patterns of observing exemplar with conventional microscope simultaneously and photomask.Then, the circuitous pattern of photomask is transferred to the front side of exemplar.
In this case, owing to the image within the depth of focus that only is in used object lens in the conventional microscope could be used conventional microscopic examination, when observing alignment patterns and circuitous pattern simultaneously, need in alignment device, adopt conventional microscope with dark depth of focus with conventional microscope.Thereby the conventional microscopical magnification with dark depth of focus reduces.
Because the CD with high density memory capacity has been developed in the improvement of design of Optical System technology and from the shortening of the ripple of the light of semiconductor laser emission recently.For example, the light beam that is focused in imaging optical system on the CD is contracted to such an extent that diameter is minimum, and the numerical aperture at the place, CD side of imaging optical system is exaggerated to obtain having the CD of high density memory capacity.In this case, the aberration degree that occurs in imaging optical system increases, because the optical axis of system is from the vertical line inclination of CD.Along with the increasing of numerical aperture, the aberration degree strengthens.In order to prevent the increasing of numerical aperture, the thickness of attenuate CD is effective.Disk thickness is represented to form the distance on the information record plane of a series of figure pits by the surface that light beam shone to it from CD (or information medium).
Fig. 3 is illustrated in the relation between the disk thickness and numerical aperture under the constant condition of optical axis angle.
As shown in Figure 3, because numerical aperture is 0.5 when disk thickness is 1.2mm, when numerical aperture increases. it is effective disk thickness being thinned to 0.6mm to 0.6 the time greatly.In this case, even numerical aperture strengthens under the constant condition of optical axis angle, the aberration degree does not strengthen yet.Thereby preferably the thickness of attenuate CD is to obtain having the CD of high density memory capacity.
Therefore, estimating that following disk thickness with high density memory capacity becomes is thinner than the existing CD of compact-disc CD (compact disk) of occurring on the present market and so on.For example, the thickness of CD is about 1.2mm, and following disk thickness is estimated not wait from 0.4mm to 0.8mm.In this case, no matter actually or need with the luminosity head system or from CD record or reproduction information and the existing following CD of CD with high density memory capacity.In other words; Need a kind of optical head device with imaging optical system, in this imaging optical system, light beam is in diffraction limit. in be focused on the CD and no matter CD is thick or thin.
Yet, in the optical head device of routine, a segment information only or CD record or reproduction from having fixed thickness.For example, the thickness of information medium 12 depart from normal range approximately ± situation 0.1mm more than under, the aberration of spherical aberration and so on appears when optical head device 11 is worked.Thereby recording of information or reproduction are impossible.Therefore, in routine techniques, have a shortcoming, promptly can't make a kind of like this optical head device, in this device, or from the CD record or reappear a segment information, no matter actually or the existing CD of the CD CD that have high density memory capacity future.
In addition, in traditional microscope, also exist a problem.In other words, because the object lens of conventional microscope have only a focus, and can only observe the image within the depth of focus that is in object lens with conventional microscope, the magnification of conventional microscope is in contradictory relation with the range of observation on optical axis direction.Thereby, exist a shortcoming, promptly can not with high power on the optical axis direction in very wide range of observation view image.
In addition, in aligning equipment, also exist a problem.In other words, when after the rear side that is drawn in exemplar in alignment patterns being drawn in circuitous pattern on the photomask when shift the front side of exemplar, the circuitous pattern by observing photomask simultaneously with the conventional microscope with dark depth of focus and low magnification and the alignment patterns of exemplar realize aiming at of photomask and exemplar.Thereby, because conventional magnifying power of microscope is low, exist the problem that can not aim at photomask with exemplar with interior high precision with 5 μ m.
Summary of the invention
One object of the present invention is, fully takes into account a kind of like this shortcoming with conventional object lens of a focus, and a kind of complex objective lens with two focuses is provided.
Another object of the present invention is to provide a kind of imaging optical system that has complex objective lens, in this system, is focused at two focal points of the different depth that is positioned at information medium with diffraction limit through the light of complex objective lens transmission.
Another object of the present invention is to provide a kind of optical head device that has imaging optical system, in this device, from or by means of one of the focal point of the effect optically focused information medium thereon of imaging optical system record, reproduction or erasure information.
Another object of the present invention is to provide a kind of high density compact disc, forms a series of first record pits in this CD, so that approaching on the substrate with all message segments of high density recording.
Another object of the present invention is to provide a kind of optical disc apparatus, in this device, with complex objective lens or from CD record or reproduction information, no matter actually or or from thin high density compact disc or from the conventional CD record of general thickness or a series of record pits of all message segments of reproduction expression.
Another object of the present invention is to provide the microscope of the bifocus with two focuses, in this microscope, observes two kinds of images that are drawn on the different depth simultaneously.
Another object of the present invention is to provide a kind of alignment device, in this device, with the bifocus microscope two kinds of images that are drawn on the different depth is aimed at.
Another object of the present invention is to provide a kind of and with the luminosity head unit light is focused on focus method on the information medium.
Another object of the present invention is to provide a kind of information reproducing method that is used for reappearing the recorded information section that is recorded on the thin high density compact disc.
According to an aspect of the present invention, a kind of optic probe device is provided, be used for beam convergence to every kind of at least two kinds of information mediums, described at least two kinds of information mediums have the transparent part of different-thickness respectively, and described at least two kinds of information mediums comprise the first information medium of first transparent part with first thickness and have second information medium of second transparent part of second thickness, to write down or to reproduce a segment information, this optic probe device comprises:
Light source is used to launch light beam;
Collimation lens, being used for the described Beam Transformation from described light source is the light of almost parallel;
Optical lens, be used for receiving from the light of the described almost parallel of described collimation lens and assemble the light of described almost parallel by transparent part, this optical lens has a plurality of zones, described a plurality of zone comprises the first area and than the second area of the optical axis of the more approaching described optical lens in first area, wherein described at least second area has relief pattern, and this optical lens can be changed into this a branch of light of the almost parallel of described reception and make light beam that passes the first area and the light beam that passes first kind of light beam of second area simultaneously, and the second kind of light beam that only passes through second area, and the described light beam that passes first area and second area simultaneously is by being focused on the first information medium at first transparent part that passes through with first numerical aperture, and and make the described light beam that only passes second area by to be focused on second information medium at second transparent part that passes through less than the second value aperture of first numerical aperture; And
A photodetector is used for receiving from the light beam of every kind of described information medium and exports electric signal.
According to another aspect of the present invention, provide a kind of optical disc apparatus, having comprised: aforesaid optic probe device; Be used for moving the mobile device of described optic probe device; With the whirligig that is used to rotate every kind of described information medium.
According to another aspect of the present invention, provide a CD, this CD comprises:
An information record substrate that is divided into first district and second district, there is first thickness in first district, and there is second thickness less than first thickness in second district;
A plurality of first districts that are positioned at information record substrate are used for the first record pit with high record density record recorded information section, and first writes down pit forms with narrow interval; And
Being used for of a plurality of second districts that are positioned at information record substrate write down pit with second of the normal recordings density record identifying information section of CD, identifying information informs that recorded information is recorded on the information record substrate with first thickness, and the recording density of recorded information is higher than the recording density of identifying information.
In above structure, the substrate of conventional CD has and the second identical thickness of second district that writes down substrate according to information in the CD of the present invention.Thereby, under a branch of reproduction light incides situation on the designation area of the unknown disc of selecting the conventional CD and CD from a group, reproduction light focuses on one of the record pit of conventional CD or second record pit of CD, no matter actually or and the conventional CD CD of unknown disc.
In unknown disc is under the situation of CD, reads one section identifying information by reproduction light.Because identifying information informs that the recorded information segment record has on the information record substrate of first thickness, the curvature of reproduction light changes automatically so that reproduction light is focused on the information record substrate with first thickness, and reproduction light is autofocusing on one of first record pit.Thereby a segment record information is reappeared.
Different therewith, be under the situation of conventional CD in unknown disc, a segment record information is read in mode same as the prior art by reproduction light.
Therefore, even do not know the thickness of information record substrate, also can reappear a segment record information that on information record substrate, forms reliably.
According to another aspect of the present invention, provide a CD, this CD comprises:
A thin information record substrate, the minimal thickness of information record substrate is thinner than the thickness of CD;
A plurality of first districts that are positioned at information record substrate are used for the first record pit with high record density record recorded information section, and first writes down pit forms with narrow interval; And
Being used for of a plurality of second districts that are positioned at information record substrate write down pit with second of low recording density record identifying information section, identifying information informs that recorded information is recorded on the thin information record substrate, the recording density of recorded information is higher than the recording density of identifying information, each second record pit is greater than the record pit on the CD, and reproduction light assembled so that focus on the common record pit that forms on the substrate of the general thickness with CD, the focal point of this reproduction light in second record one of pit formation so that read identifying information.
In above structure, the curvature of a branch of reproduction light is adjusted so that reproduction light is focused on the information record substrate of CD on the formed record pit, and this Shu Fuxian light is incident on one group and has the CD of general thickness and deciding in the district according to the unknown disc of selecting in the CD of the present invention.In unknown disc is under the situation of CD, and reproduction light is focused on one of second record pit with defocusing, because the information of CD record substrate has minimal thickness.Yet,, in the second record pit, form reproduction light focal point because each second record dimple size is big.Thereby, read one section identifying information by reproduction light.Because identifying information informs that the recorded information segment record has on the information record substrate of minimal thickness, the curvature of reproduction light changes automatically so that reproduction light is focused on the information record substrate with minimal thickness, and reproduction light is autofocusing on one of first record pit.Thereby a segment record information is reappeared.
Different therewith, be under the situation of CD in unknown disc, a segment record information is reappeared light and is read in mode same as the prior art.
Therefore, even do not know the thickness of information record substrate, also can reappear a segment record information that on information record substrate, forms reliably.
According to another aspect of the present invention, be provided with one be used for or from the optical disc apparatus of CD record or reproduction recorded information section, in this CD with high density or first substrate record or reproduction recorded information from having first thickness, and with common density one section identifying information of record on having greater than second substrate of second thickness of first thickness, this section identifying information inform or first substrate record or reproduction recorded information from having first thickness, this optical disc apparatus comprises:
Be used for making the whirligig of CD with the fixed rotating speed rotation;
The light source of an a branch of incident light of emission;
Be used on the emitting light path without any the transmission of diffraction ground from a part of incident light of light emitted with form a branch of transmitted light and on emitting light path diffraction from the remainder incident light of light emitted forming the hologram apparatus of a branch of diffraction light, hologram apparatus plays lensing to diffraction light so that disperse diffraction light from hologram apparatus;
Be used for the transmitted light that in hologram apparatus, forms be focused at by on first substrate of the CD of whirligig rotation in case or from the CD record or on reappearing a segment record information and the diffraction light that forms hologram apparatus being focused at by second substrate of the CD of whirligig rotation so that from the lens devices of CD reproduction identifying information, transmitted light is reflected lens devices and the hologram apparatus that also passes once more on the input path by first substrate of CD, and diffraction light is reflected lens devices and the hologram apparatus that also passes once more on the input path by second substrate of CD.
Be used for changing the lens devices that passes on the input path and hologram apparatus transmitted light wave front with form one or more recorded information light beams and change the lens dress cover that passes on the input path and the wave front of the diffraction light of hologram apparatus to form the wave front modifier of one or more identifying information light beams;
Be used for surveying by the formed recorded information light intensity of wave front modifier and also survey by the formed identifying information light intensity of wave front modifier so that generate the sniffer of identifying information signal according to the identifying information light intensity so that generate recording information signal according to the recorded information light intensity, the representative of identifying information signal is recorded in the second on-chip identifying information of CD, and the recording information signal representative is recorded in the first on-chip recorded information of CD; And
Be used in sniffer, surveying therein under the situation of identifying information, move the optical-head apparatus that comprises light source, hologram apparatus, lens devices and sniffer, so that formed diffraction light in hologram apparatus is converged on second substrate of CD, and move wherein that formed diffraction light is converged to the second on-chip CD of CD in hologram apparatus, so that formed transmitted light in hologram apparatus is converged to the first on-chip mobile device of CD.
In above structure, an optical head device that comprises light source, hologram apparatus, lens devices and sniffer has the structure identical with aforementioned person.At first, optical head device mobile device moves, so that formed diffraction light in hologram apparatus is focused on second substrate that converges to the CD that is rotated by whirligig.Thereby, be recorded in the second on-chip identifying information and in sniffer, reappeared, and it inform or first substrate record or reproduction recorded information section from having first thickness.After this, the optical head device is moved device and moves, so that formed transmitted light in hologram apparatus is focused on first substrate that is focused at the CD that is rotated by whirligig.Thereby, or from first substrate of CD record or reappear a segment record information.
Therefore, though use recorded information section wherein or the high density compact disc that is recorded or reappears from the substrate that has less than first thickness of second thickness of conventional CD, recorded information also can reliable recording or reproduction.
According to another aspect of the present invention, provide one be used for or from the optical disc apparatus of CD record or reproduction recorded information section, in this CD, with high density or from first substrate record or the reproduction recorded information of minimal thickness with the thickness that is thinner than CD, and with low-density have on second substrate of minimal thickness record inform or from first substrate record with minimal thickness or one section identifying information of reproduction recorded information, this optical disc apparatus comprises:
Be used for making the whirligig of CD with the fixed rotating speed rotation;
The light source of an a branch of incident light of emission;
Be used on the emitting light path without any the transmission of diffraction ground from a part of incident light of light emitted with form a branch of transmitted light and on emitting light path diffraction from the remainder incident light of light emitted forming the hologram apparatus of a branch of diffraction light, hologram apparatus plays lensing to diffraction light so that disperse diffraction light from hologram apparatus;
Be used for the transmitted light that in hologram apparatus, forms focus on assemble (convergingin focus) on by first substrate of the CD of whirligig rotation in case or from the CD record or reappear a segment record information, and the diffraction light that in hologram apparatus, forms defocus convergences (converging in defocus) on by second substrate of the CD of whirligig rotation in case reappear from the lens devices of optical disc identification information, transmitted light is reflected lens devices and the hologram apparatus that also passes once more on the input path by first substrate of CD, and lens devices and holography that diffraction light is also passed on the input path once more by the reflection of second substrate of CD cease map device;
The wave front of transmitted light that is used for changing the lens devices that passes on the input path and hologram apparatus to be forming one or more recorded information light beams, and the wave front of diffraction light that changes the lens devices that passes on the input path and hologram apparatus is to form the wave front modifier of one or more identifying information light beams;
Be used for surveying by the formed recorded information light intensity of wave front modifier so that generate recording information signal according to the recorded information light intensity, and survey by the formed identifying information light intensity of wave front modifier so that generate the sniffer of identifying information signal according to the identifying information light intensity, the representative of identifying information signal is recorded in the second on-chip identifying information of CD, and the recording information signal representative is recorded in the first on-chip recorded information of CD; And
Under the situation of intensity greater than a threshold value of the identifying information signal that is used in sniffer, generating therein, move the optical head device that comprises light source, hologram apparatus, lens devices and sniffer, so that formed diffraction light in hologram apparatus is defocused on second substrate that converges to CD, and move wherein that formed diffraction light is defocused the second on-chip CD that converges to CD in hologram apparatus, so that a formed transmitted light in hologram apparatus is focused on the first on-chip mobile device that converges to CD.
In above structure, an optical head device that comprises light source, hologram apparatus, lens devices and sniffer has the structure identical with aforementioned person.At first, the optical head device is moved by mobile device, so that formed diffraction light in hologram apparatus is defocused on second substrate that converges to the CD that is rotated by whirligig.In this case, because identifying information writes down with low-density, the record pit of a plurality of representative identifying informations is respectively large-sized.Thereby, even defocusing, diffraction light is focused on each record pit, also in each record pit, form the focal point of a diffraction light.Thereby, be recorded in the second on-chip identifying information and in sniffer, reappeared, and inform or first substrate record or reproduction recorded information section from having minimal thickness.After this, the optical head device is moved device and moves, so that formed transmitted light in holographic apparatus is focused on first substrate that is focused at the CD that is rotated by whirligig.Thereby, or from first substrate of CD record or reappear a segment record information.
Therefore, though use recorded information section wherein or from having the CD less than the high density type of the substrate record of the minimal thickness of the general thickness of conventional CD or reproduction, recorded information also can reliable recording or reproduction.
According to another aspect of the present invention, provide one to be used for observing simultaneously the bifocus microscope that places the image of first on first image plane and place second image on second image plane, this microscope comprises:
Object lens that are used for reflecting a branch of first light of dispersing from first image and a branch of second light of dispersing from second image, the distance of first between first image of the object lens and first image plane are different from the second distance between second image of the object lens and second image plane;
One be used for without any the transmission of diffraction ground by first light that object lens reflected with form a branch of transmitted light and diffraction by second light that object lens were reflected to form the hologram lens of a branch of diffraction light, the hologram lens play lensing to second light, so that make diffraction light and transmitted light pass identical light path, and form a branch of superimposed light by transmitted light and diffraction light;
One is used for converging at the image point of the 3rd image plane by the formed superimposed light of hologram lens so that form first image of amplification and the interior lens of second image simultaneously on the 3rd image plane; And
One is used for assembling the superimposed light of can coalescence being dispersed from image point by interior lens so that forms the eyepiece of first visual and second image that further amplifies simultaneously.
In above structure, first light beam of dispersing from first image and reflected by object lens together from second light beam that second image is dispersed.In this case, since first between first image of object lens and first image plane apart from the second distance between second image that is different from the object lens and second image plane, so the curvature of first refract light is different from another curvature of second refract light.After this, first refract light through the hologram lens without any the transmission of diffraction ground forming a branch of transmitted light, and second refract light by hologram lens diffraction to form a branch of diffraction light.In this case, because the hologram lens play lensing to diffraction light, so the curvature of diffraction light is consistent with the curvature of transmitted light.In other words, diffraction light passes identical light path with transmitted light.Thereby, form a stack light beam by transmitted light and diffraction light.After this, superimposed light is converged at an image point place of the 3rd image plane by interior lens, so that forms first image and second image that amplifies on the 3rd image plane simultaneously.After this, assembled by eyepiece, so that form first image and second image that further amplifies simultaneously from the superimposed light that image point is dispersed.
Therefore, the operator can observe first image and second image of enough amplifications.
According to another aspect of the present invention, provide one to be used for observing simultaneously the bifocus microscope that places the image of first on first image plane and place second image on second image plane, this microscope comprises:
Object lens that are used for reflecting a branch of first light of dispersing from first image and a branch of second light of dispersing from second image, the distance of first between first image of the object lens and first image plane are different from the second distance between second image of the object lens and second image plane;
One is used for without any the transmission of diffraction ground by first light that object lens reflected to form a branch of transmitted light, and diffraction by second light that object lens reflected to form the hologram lens of a branch of diffraction light, the hologram lens play lensing to second light, so that make diffraction light and transmitted light pass identical light path, and form a branch of superimposed light by transmitted light and diffraction light;
One is used for the image point that converges at the 3rd image plane by the formed superimposed light of hologram lens is sentenced the interior lens that just form first visual and second image that amplifies on the 3rd image plane simultaneously; And
By in interior lens, assemble superimposed light in the 3rd image plane photographs by first image that amplifies and the photographic means of the second visual stack image that forms.
In above structure, first image and second image of amplification form on the 3rd image plane in the same manner simultaneously.After this, first of the amplification image and second image are taken by photographic means as the stack image.
Therefore, can observe first image and second image of amplification.
According to a further aspect of the present invention, provide one to be used for being drawn in the alignment device that first reference picture on the photomask is aimed at second reference picture on being drawn in exemplar, this alignment device comprises:
An emission alignment is so that the light source of first and second reference pictures that throw light on;
Object lens that are used for not only reflecting a branch of first alignment light of dispersing from first reference picture but also reflect a branch of second alignment light of dispersing from second reference picture, these reference pictures are thrown light on by the alignment light from light emitted, and the distance between first reference picture of object lens and photomask is different from the distance between second reference picture of object lens and exemplar;
One is used for without any the transmission of diffraction ground by first alignment light that object lens reflected to form a branch of transmitted light, and diffraction by second alignment light that object lens reflected to form the hologram lens of a branch of diffraction light, the hologram lens play lensing to second alignment light so that make diffraction light and transmitted light pass identical light path, and form a branch of superimposed light by transmitted light and diffraction light;
One is used for converging at the image point of an image plane so that form the interior lens of first and second reference pictures that amplify simultaneously on image plane by the formed superimposed light of hologram lens, and an optical axis passes the center of object lens, hologram lens and interior lens;
By in interior lens, assemble superimposed light in the image plane photographs by first image that amplifies and the photographic means of the second visual stack image that forms; And
Be used for according to coming mobile photomask or exemplar so that first reference picture and second reference picture mobile device along optical axis alignment by the captured stack image of photographic means.
In above structure, object lens, hologram lens and interior lens are identical with in the bifocus microscope those.Thereby first image and second image of the amplification on the image plane are taken by photographic means as the stack image.After this, photomask or exemplar are moved device and move along the direction vertical with optical axis, so as first reference picture and second reference picture along optical axis alignment.
Therefore, since captured by the formed stack image of first and second reference pictures that amplify by photographic means, the relative position between first and second reference pictures can be observed exactly.Thereby first reference picture can be aimed at second reference picture exactly.
According to a further aspect of the present invention, provide a kind of be used for that light focused on the first information medium with first thickness or have on second information medium of second thickness so as or from first information medium or second information medium record or reappear the focus method of a segment information, the method comprising the steps of:
Move the optical head device along the direction that reduces or strengthen distance between the optical head device and first or second information medium, the optical head device comprises:
The light source of an a branch of incident light of emission,
Be used on emitting light path without any a diffraction ground transmission part from the incident light of light emitted to form a branch of transmitted light, and on emitting light path the diffraction remainder from the incident light of light emitted to form the hologram apparatus of a branch of diffraction light, hologram apparatus plays lensing to diffraction light so that disperse diffraction light or assemble diffraction light from hologram apparatus
Be used on the emitting light path formed transmitted light in hologram apparatus being converged at first focal length so that form first focal point on the front surface of first information medium, or on the emitting light path formed diffraction light in hologram apparatus is being converged at second focal length so that form the lens devices of second focal point on the front surface of second information medium, transmitted light incident and converge at the front surface of first information medium on the rear surface of first information medium, transmitted light is reflected at place, the rear surface of first information medium and passes lens devices and hologram apparatus on the input path once more, diffraction light incident and converge at the front surface of second information medium on the rear surface of second information medium, and diffraction light is reflected at place, the rear surface of second information medium and passes lens devices and hologram apparatus on the input path once more
The wave front that is used for changing the transmitted light of the lens devices that passes on the input path and hologram apparatus or diffraction light to be forming the wave front modifier of one or more information carrying beams, and
Be used for surveying by the formed information light intensity of wave front modifier and according to the information light intensity and generate the sniffer of information signal and focus error signal, information signal represents to be recorded in the segment information on the first information medium or second information medium;
Whether the intensity of the focus error signal that judgement generates in sniffer is greater than a threshold value; And
When the intensity of focus error signal becomes greater than threshold value, adjust the position of optical head device so that the intensity of focus error signal is reduced to zero.
In above step, utilize above-mentioned optical head device to realize focus method.When the distance between the lens devices and first or second information medium approached the focal length of lens devices, the intensity of focus error signal increased greatly.Thereby when the intensity of focus error signal became greater than threshold value, lens devices was positioned near real focus, and transmitted light or refract light focus on and be focused on first or second information medium in lens devices.
Thereby the position of adjusting the optical head device when the intensity when focus error signal becomes greater than threshold value is so that be reduced to the intensity of focus error signal under the zero situation, and transmitted light or diffraction light can focus on first or second information medium.
According to a further aspect of the invention, providing a kind of is used for from the information reproducing method of CD reproduction one segment record information, in this CD recorded information have with high density recording on first substrate of first thickness and one section inform that recorded information is recorded in the first on-chip identifying information and is recorded in common density on second substrate that has greater than second thickness of first thickness, the method comprising the steps of:
Move an optical disc apparatus under second substrate of CD, CD comprises:
Be used for making the whirligig of CD with the fixed rotating speed rotation,
The light source of an a branch of incident light of emission,
Be used on emitting light path without any a diffraction ground transmission part from the incident light of light emitted to form a branch of transmitted light, and on emitting light path the diffraction remainder from the incident light of light emitted to form the hologram apparatus of a branch of diffraction light, hologram apparatus plays lensing so that disperse diffraction light from hologram apparatus to diffraction light
Be used for the lens light of formation in hologram apparatus be focused at by on first substrate of the CD of whirligig rotation just or from the CD record or reappear a segment record information, and the diffraction light of formation in hologram apparatus be focused at by on second substrate of the CD of whirligig rotation in case reproduction from the lens devices of the discernible signal of CD, transmitted light is reflected lens devices and the hologram apparatus that also passes once more on the input path by first substrate of CD, and diffraction light is reflected lens devices and the hologram apparatus that also passes once more on the input path by second substrate of CD
The wave front of transmitted light that is used for changing the lens devices that passes on the input path and hologram apparatus is to form one or more recorded information light beams, and the wave front of diffraction light that changes the lens devices pass on the input path and hologram apparatus to be forming the wave front modifier of one or more identifying information light beams, and
Be used for surveying by the formed recorded information light intensity of wave front modifier so that generate recording information signal according to the recorded information light intensity, and survey by the formed identifying information light intensity of wave front modifier so that generate the sniffer of identifying information signal according to the identifying information light intensity, the representative of identifying information signal is recorded in the second on-chip identifying information of CD, and the recording information signal representative is recorded in the first on-chip recorded information of CD;
Diffraction light is focused on second substrate of CD so that the reproduction identifying information;
When mobile optical disc apparatus to a position is detected identifying information with box lunch under first substrate of CD in sniffer, transmitted light is focused on first substrate of CD; And
Reappear recorded information by in sniffer, generating recording information signal.
In above step, utilize above-mentioned optical disc apparatus to realize the information reproducing method.Reappear the second on-chip identifying information that is positioned at CD with diffraction light.In this case, because second substrate has second thickness, diffraction light just focuses on second substrate.After this, when detecting identifying information, optical disc apparatus is moved to the position at first substrate of CD, and transmitted light is focused on first substrate of CD.In this case, because first substrate has first thickness, transmitted light just focuses on first substrate.
Therefore, can reappear recorded information reliably.
Description of drawings
From the following description of being done in conjunction with the accompanying drawings, purpose of the present invention, feature and advantage will be conspicuous, in these accompanying drawings:
Fig. 1 is the constitutional diagram of the conventional optical head device that proposed in 1991 the 46630th at Japanese patent application;
Fig. 2 A, 2B are respectively the sectional views of object lens shown in Fig. 1 and blazed hologram assembly;
Fig. 3 is illustrated in the relation between the numerical aperture of the thickness of CD under the constant condition of optical axis angle and object lens;
Fig. 4 A is the constitutional diagram that has according to the imaging optical system of the complex objective lens of the first embodiment of the present invention, and the transmitted light of a branch of no diffraction is focused on the slim information medium;
Fig. 4 B is the constitutional diagram of the imaging optical system shown in Fig. 4 A, and a branch of first-order diffraction optical convergence is on a thick type information medium;
Fig. 5 is the planimetric map of the hologram lens shown in Fig. 4 A, the 4B, the raster graphic of the hologram lens that draw;
Fig. 6 is the sectional view of the hologram lens shown in Fig. 5, is illustrated in the raster graphic that forms embossment on the hologram lens;
Fig. 7 is the key diagram of intensity distributions of the transmitted light L4 at the expression focal point S1 place that is focused at first information medium, principal maximum occurs and held back secondary maximum in focal point S1;
Fig. 8 A is the sectional view of the lens of hologram shown in Fig. 5, and expression is similar to the step-like raster pattern figure that is made up of four steps;
Fig. 8 B is the sectional view of the lens of hologram shown in Fig. 5, and expression is similar to the step-like raster graphic of being made up of a plurality of steps;
Fig. 9 A is the constitutional diagram that has according to the imaging optical system of the complex objective lens of the modification of first embodiment, and a branch of first-order diffraction optical convergence is on slim information medium;
Fig. 9 B is the constitutional diagram of imaging optical system shown in Fig. 9 A, and the transmitted light of a branch of no diffraction is focused on the thick type information medium;
Figure 10 A is the constitutional diagram that has according to the imaging optical system of the complex objective lens of the second embodiment of the present invention, and the transmitted light of a branch of no diffraction is focused on the slim information medium;
Figure 10 B is the constitutional diagram of imaging optical system shown in Figure 10 A, and a branch of first-order diffraction optical convergence is on thick type information medium;
The variation of hologram lens diffraction efficiency shown in Figure 11 presentation graphs 10A, the 10B;
Figure 12 A to 12E is respectively the sectional view of hologram lens shown in Figure 10 A, the 10B, and the raster graphic of hologram lens is similar to stepped appearance;
Figure 13 A represents intensity distribution of incident light used among second embodiment, and the far-field pattern of incident light distributes by Gaussian distribution;
Figure 13 B represents the intensity distributions through the transmitted light of the transmission of hologram lens shown in Figure 10, the 10B, and the far-field pattern of incident light is by the gentle slope distribution of shapes;
Figure 14 A to 14C represents through the transmitted light of the transmission of hologram lens shown in Figure 10 A, the 10B and the intensity distributions of diffraction light;
Figure 15 A is the planimetric map according to the hologram lens of the modification of second embodiment, the raster graphic of the hologram lens that draw;
Figure 15 B, 15C are respectively the constitutional diagrams that has according to the imaging optical system of the complex objective lens of another modification of second embodiment;
Figure 16 A is the constitutional diagram that has according to the imaging optical system of the complex objective lens of the third embodiment of the present invention, and a branch of first-order diffraction optical convergence is on slim information medium;
Figure 16 B is the constitutional diagram of imaging optical system shown in Figure 16 A, and the transmitted light of a branch of no diffraction is focused on the thick type information medium;
The variation of the diffraction efficiency of hologram lens shown in Figure 17 presentation graphs 16A, the 16B;
Figure 18 A to 18C represents through the transmitted light of the transmission of hologram lens shown in Figure 16 A, the 16B and the intensity distributions of diffraction light;
Figure 19 A is the sectional view according to the complex objective lens of the fourth embodiment of the present invention;
Figure 19 B is the sectional view according to the complex objective lens of the modification of the fourth embodiment of the present invention;
Figure 20 is the sectional view according to the complex objective lens of the fifth embodiment of the present invention;
Figure 21 is the constitutional diagram according to the optical head device of the sixth embodiment of the present invention;
Figure 22 is the planimetric map that is used for the wave front modifier of the 6th, the 9th and the 12 embodiment, draws as the raster graphic of the hologram lens of wave front modifier;
Figure 23 expresses the position relation between the diffraction light focus in wave front modifier shown in present Figure 22 and the photodetector;
Figure 24 be used for the the 6th, the 9th, the tenth, the 12, the 13 and the planimetric map of the photodetector of the 17 embodiment;
Figure 25 A and 25C be illustrated respectively in object lens shown in Figure 21 under the condition that defocuses on the information medium to the focal point of the first-order diffraction light of detecting area SE1, the SE2 of the photodetector of sextant shown in Figure 24 and SE3 emission with to another focal point of the negative first-order diffraction light of detecting area SE4, the SE5 of sextant photodetection and SE6 emission;
Figure 25 B is illustrated in object lens and just in time focuses under the condition on the information medium to the focal point of the first-order diffraction light of detecting area SE1, the SE2 of sextant photodetector and SE3 emission with to another focal point of the negative first-order diffraction light of detecting area SE4, the SE5 of sextant photodetector and SE6 emission;
Figure 26 expresses the relation between the diffracted beam in the photodetector shown in the wave front modifier shown in present Figure 22 and Figure 24;
Figure 27 is the constitutional diagram according to the optical head device of the 7th embodiment;
Figure 28 be used for the the 7th, the 9th, the tenth, the 12 and the planimetric map of the photodetector of the 13 embodiment;
Figure 29 A, 29B, 29C represent to be focused at the different shape of the focal point on the photodetector shown in Figure 28;
Figure 29 D represents radially Dr and tangential Dt;
Figure 30 is the constitutional diagram according to the first optical head device of revising of the 7th embodiment;
Figure 31 is the constitutional diagram according to the second optical head device of revising of the 7th embodiment;
Figure 32 is the constitutional diagram according to the 3rd optical head device of revising of the 7th embodiment;
Figure 33 is the constitutional diagram according to the 4th optical head device of revising of the 7th embodiment;
Figure 34 represent a branch of at no diffraction on the input path transmitted light and a branch of on input path the transmitted light of diffraction, light beam is used for the detection information signal;
Figure 35 A illustrates the variation of the focus error signal that obtains by detection transmission light intensity, and the intensity of focus error signal depends on the distance between object lens and the first information medium;
Figure 35 B illustrates the variation of the focus error signal that obtains by detection diffraction light intensity, and the intensity of focus error signal depends on the distance between the object lens and second information medium;
Figure 36 A illustrates the variation of the focus error signal that obtains by detection diffraction light intensity, and the intensity of focus error signal depends on the distance between object lens and the first information medium;
Figure 36 B illustrates the variation of the focus error signal that obtains by detection transmission light intensity, and the intensity of focus error signal depends on the distance between the object lens and second information medium;
Figure 37 is the constitutional diagram according to the optical head device of the 9th embodiment;
Figure 38 is the constitutional diagram according to the optical head device of the tenth embodiment;
Figure 39 is the planimetric map that is used for the beam splitter that has reflection hologram of the device of optical head shown in Figure 38;
Figure 40 A, 40B are respectively the constitutional diagrams according to the optical head device of the 11 embodiment;
Figure 41 is the planimetric map that is used for the beam splitter that has reflection hologram of the device of optical head shown in Figure 38;
Figure 42 A and 42C are illustrated respectively in diffraction light and defocus under the condition that is focused on second information medium to the focal point of the first-order diffraction light of detecting area SE1, the SE2 of the photodetector of sextant shown in Figure 24 and SE3 emission with to another focal point of the negative first-order diffraction light of detecting area SE4, the SE5 of sextant photodetector and SE6 emission;
Figure 42 B is illustrated in diffraction light and focuses under the condition be focused on second information medium to the focal point of the first-order diffraction light of detecting area SE1, the SE2 of the photodetector of sextant shown in Figure 24 and SE3 emission with to another focal point of the negative first-order diffraction light of detecting area SE4, the SE5 of sextant photodetector and SE6 emission;
Figure 43 is the constitutional diagram according to the optical head device of the 12 embodiment;
Figure 44 is the constitutional diagram according to the optical head device of the 13 embodiment;
Figure 45 is the constitutional diagram according to the optical head device of the 14 embodiment;
Figure 46 is the planimetric map that is used for the hologram lens of the optical head device shown in Figure 45;
Figure 47 is the constitutional diagram according to the optical head device of the 15 embodiment;
Figure 48 is the planimetric map that is used for the hologram lens of the optical head device shown in Figure 47;
Position relation between the unnecessary light that Figure 49 A, 49B represent respectively to occur in the photodetector shown in the lens of hologram shown in Figure 48 and Figure 47;
Figure 50 is the constitutional diagram according to the optical head device of the 16 embodiment;
Figure 51 is used for the light source of the device of optical head shown in Figure 50 and the axonometric drawing of photodetector;
Figure 52 is the constitutional diagram according to the optical head device of the 17 embodiment;
Figure 53 is the axonometric drawing according to the high density compact disc of the 18 embodiment, the sectional view of local indicating panel;
Figure 54 is the axonometric drawing according to the high density compact disc of the 19 embodiment, the sectional view of local indicating panel;
Figure 55 is the calcspar that has the optical disc apparatus of one of optical head device shown in Figure 21,27,30,31,32,33,37,38, the 40A, 43,44,50 and 52 according to the 20 embodiment;
Figure 56 is the process flow diagram of the work of the optical disc apparatus shown in expression Figure 55;
Figure 57 is the calcspar that has the optical disc apparatus of one of optical head device shown in Figure 21,27,30,31,32,33,37,38, the 40A, 43,44,50 and 52 according to the 21 embodiment;
Figure 58 is the process flow diagram of the work of optical disc apparatus shown in expression Figure 57;
Figure 59 is according to the microscopical constitutional diagram of the bifocus of the 22 embodiment;
Figure 60 is positioned at the microscopical local figure of bifocus shown in Figure 59 under the situation of exemplar frame bottom at first and second exemplars;
Figure 61 is according to the microscopical constitutional diagram of the bifocus of the modification of the 22 embodiment;
Figure 62 is the constitutional diagram according to the alignment device of the 23 embodiment.
Embodiment
The contrast accompanying drawing is described the most preferred embodiment according to complex objective lens of the present invention, imaging optical system, optic probe device, CD, optical disc apparatus, bifocus microscope and alignment device.
(first embodiment)
Fig. 4 A is the constitutional diagram that has according to the imaging optical system of the complex objective lens of the first embodiment of the present invention, and the transmitted light of a branch of no diffraction is focused on the slim information medium.Fig. 4 B is the constitutional diagram of the imaging optical system shown in Fig. 4 A, and a branch of first-order diffraction optical convergence is on a thick type information medium.Fig. 5 is the planimetric map of the hologram lens shown in Fig. 4 A, the 4B, the raster graphic of the hologram lens that draw.
As Fig. 4 A, shown in the 4B, one be used for an optical convergence on second substrate 24 of first substrate 22 of slim first information medium 23 (thickness T 1) or thick type second information medium 25 (thickness T 2) to form the imaging optical system 21 of diffraction limited focal point, comprise that one is used for without any a diffraction ground transmission part from the incident light L3 of light emitted with the remainder that forms a branch of transmitted light L4 and diffraction incident light L3 forming the blazed hologram lens 26 of a branch of first-order diffraction light L5, and one is used for transmitted light L4 is focused on the first information medium 23 or first-order diffraction light L5 is focused at object lens 27 on second information medium 25.
23 representatives of first information medium have the CD in the future of high density memory capacity, and the thickness T 1 of first information medium 23 is in 0.4mm to 0.8mm scope.CD or laser disk that 25 representatives of second information medium occur in the market, and the thickness T 2 of second information medium 25 is about 1.2mm.
" convergence " speech represents that in this manual diverging light or directional light are focused to form diffraction limit low-light point.
In above structure, the part of parallel incident light L3 forms a branch of transmitted light (being a branch of zero order diffracted light L4) without any 26 transmissions of diffraction ground warp holographic lens.After this, transmitted light L4 is assembled by object lens 27.In addition, the remainder of incident light L3 is formed a branch of first-order diffraction light L5 by hologram lens 26 diffraction and refraction.In this case, 26 pairs of first-order diffraction light of hologram lens L5 plays concavees lens selectively, so that first-order diffraction light L5 disperses from hologram lens 26.After this, first-order diffraction light L5 is assembled by object lens 27.
Slim first information medium 23 be used to or under the situation of the front surface of medium 23 record or reproduction message segment, as shown in Fig. 4 A, transmitted light L4 is incident on the rear surface of first information medium 23 and is focused on by object lens 27 on the front surface of first information medium 23 so that form diffraction limited focal point S1 on first information medium 23.Different therewith, thick type second information medium 25 be used to or under the situation of the front surface of medium 25 record or reproduction message segment, diffraction light L5 is incident on the rear surface of second information medium 25 and focuses on its front surface so that form diffraction limited focal point S2 on second information medium 25.Because 26 concavees lens of hologram lens are done even the thickness T 1 of first information medium 23 is different from the thickness T 2 of second information medium 25, also to form diffraction limited focal point S1, S2 in order to disperse one section diffraction light L5.Thereby in fact the complex objective lens of being made up of hologram lens 26 and object lens 27 29 has two focuses.
In addition, as shown in Figure 5, by in the graph area 26A of transparent substrate 28, forming hologram lens 26 with the concentric circles raster graphic P1 that draws.Graph area 26A is positioned at the middle part of transparent substrate 28, is not positioned at the circumference of transparent substrate 28 so that spiral figure district 26A and there is graph area 26B.The optical axis of imaging optical system 21 passes the central point of raster graphic P1 and the central shaft of object lens 27.
In addition, as shown in Figure 6, the raster graphic P1 of hologram lens 26 forms embossment to produce phase modulation-type hologram lens.In other words, in raster graphic P1, form the piece that each is made up of bottom and top with one heart.The height H of embossment is set as among the raster graphic P1:
H＜λ/(n(λ)-1)(1)
Sign of lambda is represented the wavelength of incident light L3 and symbol n (λ) represents the refractive index of 28 couples of incident light L3 of transparent substrate in the formula.In this case, through the incident light L3 of the bottom of raster graphic P1 transmission and between the incident light L3 of the top of raster graphic P1 transmission the difference of phase modulation (PM) degree less than 2 π radians.Thereby, 26 pairs on hologram lens through the diffraction efficiency of the incident light L3 of raster graphic P1 transmission less than 100% so that generate light L4 through raster graphic P1 transmission.Moreover, not diffracted through the incident light L3 of no graph area 26B transmission.As a result, the intensity of transmitted light L4 may be enough to or from first information medium 23 record or reproduction message segment.
Moreover, because the intensity of transmitted light L4 is enough, can suppress undesirably to appear at the secondary maximum (side wave lobe) among the focal point S1 on the whole surface of hologram lens 26.In detail, when the intensity distributions of gathering the transmitted light L4 on focal point S1 entirely as shown in Figure 7 the time, the principal maximum (main lobe) that is positioned at the transmitted light L4 at focal point S1 center be used for or from first information medium 23 records or reappear a segment information, and the secondary maximum that is positioned at around the principal maximum is unnecessary, because secondary maximum is damaged record pit or the reproduction signal that is formed by principal maximum.
The raster graphic P1 that forms the hologram lens 26 of embossment is excited (blazed) as shown in Figure 6, so that suppresses the appearance of negative first-order diffraction light significantly.Thereby, intensity and the maximum of transmitted light L4 and first-order diffraction light L5.In other words, improved the utilization factor of incident light L3.
The numerical aperture NA of object lens 27 is equal to or greater than 0.6.Moreover, when transmitted light L4 is assembled by object lens 27, have formation diffraction limited focal point S1 on the first information medium 23 of thickness T 1.
The diameter of hologram lens 26 is almost mutually identical with the aperture of object lens 27, so that the diameter of graph area 26A is less than the aperture of object lens 27.Because not diffracted, not only be focused on the first information medium 23 through the light L4 of graph area 26A transmission but also through the object lens 27 that the light L4 of no graph area 26B transmission is had a large-numerical aperture through the incident light L3 of no graph area 26B transmission.Thereby, can increase the intensity of the transmitted light L4 that converges at focal point S1.L4 is different with transmitted light, only becomes first-order diffraction light L5 through the incident light L3 of the graph area 26A of hologram lens 26 transmission, and the object lens 27 that in fact first-order diffraction light L5 is had a small value aperture are focused on second information medium 25.
The mean value that depends on the phase modulation (PM) degree in the light L4 of the bottom of raster graphic P1 and top transmission through the phase place of the light L4 of the raster graphic P1 of graph area 26A transmission.Different therewith, because the constant height of no graph area 26B, modulate with a phase modulation (PM) degree through the phase place of the light L4 of no graph area 26B transmission.Thereby as shown in Figure 6, the height of no graph area 26B is set as with the average height of raster graphic P1 and evens up so that improve the converging action of object lens 27.
For example, as shown in Fig. 8 A, under the situation that every of raster graphic P1 is similar to the stairstepping of being made up of four steps in the lens of hologram shown in Fig. 6 26, first step is etched into dark h1+h2 and wide W1, second step is etched into dark h1 and wide W2, the 3rd step is etched into dark h2 and wide W2, and the 4th step is etched into wide W1.Thereby, in graph area 26A, form the raster graphic P1 that is similar to stairstepping.After this, the peripheral part of transparent substrate 28 is etched into dark h1 or h2 to form no graph area 26B.Thereby the height of the no graph area 26B almost average height with graph area 26A is identical, so that almost identical with phase place through the light L4 of no graph area 26B transmission through the phase place of the light L4 of graph area 26A transmission.
In addition, shown in Fig. 8 B, the desirable shape of glittering of the lens of hologram shown in Fig. 6 26 may be similar to the stairstepping that obtains by etching transparent substrate 28 middle parts repeatedly.In this case, the height H 0 of stairstepping is set as the difference that satisfies equation H0＜λ/(n (λ)-1) so that phase modulation (PM) degree and is set as value less than 2 π radians.Specifically, herein the stairstepping of hologram lens 26 by having equal height difference n 0One section N step situation about forming under, difference in height n 0Be set as and satisfy equation n 0＜λ/((n (λ)-1) * N) is so that be set as value less than 2 π/N radian to the difference of the phase modulation (PM) degree of each step.The peripheral part of transparent substrate 28 is etched so that the thickness of no graph area 26B is set as neither the thickness of the graph area 26A that one of N the step on the also non-base frame of top step rank located.Thereby the height of the no graph area 26B almost average height with graph area 26A is identical, so that almost identical with phase place through the light L4 of no graph area 26B transmission through the phase place of the light L4 of graph area 26A transmission.
The raster graphic P1 of hologram lens 26 is designed to revise any aberration that occurs in the object lens 27 and second information medium 25, so that first-order diffraction light L5 through having thickness T 2 25 transmissions of second information medium and be focused on the medium 25 so that be provided with any aberration ground formation diffraction limited focal point S2.A kind of method that is used for designing the hologram lens 26 with aberration debugging functions is described.
After first-order diffraction light L5 was focused on second information medium 25, spherical wave was dispersed and through second substrate 24 and object lens 27 transmissions from focal point S2.After this, spherical wave through transparent substrate 28 transmissions and with incident light L3 optical interference.Thereby, form a conoscope image by the interference between spherical wave and the incident light L3.The phase place that deducts spherical wave the paraphase position that obtains from the phase place of upset incident light L3 can be calculated conoscope image.Therefore, can form the raster graphic P1 of the holographic lens 26 that meets the conoscope image of being calculated very at an easy rate according to the computer hologram method of formation.
Therefore, because complex objective lens 29 is made up of object lens 27 and hologram lens 26, diffracted and the refraction of a part of incident light L3 still is a thickness T 2 so no matter information medium has thickness T 1 actually in hologram lens 26, can both form the diffraction limited focal point on information medium reliably.Moreover two diffraction limited focal points can form on the information medium different depth simultaneously.In other words, in fact complex objective lens has two focuses.
Moreover, since the diffraction efficiency of hologram lens 26 less than 100% and through the intensity of the light L4 of holographic lens 26 transmissions be enough to or from first information medium 23 record or reproduction information, so can suppress to be focused at the secondary maximum of the transmitted light L4 on the focal point S1.
Moreover, because hologram lens 26 are excited, can suppress the appearance of negative first-order diffraction light significantly.Thereby, the intensity of transmitted light L4 and first-order diffraction light L5 and be maximum, and can improve the utilization factor of incident light L3.
Moreover because holographic lens 26 only plays lensing to first-order diffraction light, the position of the focal point S1 that is formed by transmitted light L4 along optical axis direction is different from the position of the focal point S2 that is formed by first-order diffraction light L5.Thereby, when transmitted light L4 focuses on the information record plane be focused at information medium 23 so that record or when reading a segment information, be focused at first-order diffraction light L5 on the information medium 23 in place, information record plane out of focus.In like manner, when first-order diffraction light L5 focused on the information record plane that is focused at information medium 25, the transmitted light L4 that is focused on the information medium 25 located out of focus on information record plane.Therefore, be focused at that focal point S1 (or S2) goes up so that when record or sense information when light L4 (or L5) focuses on, out-focus is focused at light L5 (or L4) on the focal point S1 (or S2) to recording of information or read and do not have harmful effect.In order to prevent reliably, require that the difference along optical axis direction is equal to or greater than 50 μ m between focal point S1, the S2 to the recording of information or the harmful effect of reading.In other words, when this difference is equal to or greater than 50 μ m, light L4 (or L5) was focused on the focal point S1 (or S2) on information record plane with high strength when, light L5 (or L4) dispersed in large quantities so that reduces the intensity that light L5 (or L4) locates on information record plane.
Moreover, owing to represent the thickness T 2 of second information medium 25 of CD or laser disk to be about 1.2mm, and since the thickness T 1 of first information medium 23 of CD of represent future in the scope of 0.4mm to 0.8mm, consider range of movement, require that the alternate position spike along optical axis direction is equal to or less than 1.0mm between focal point S1, the S2 so as to the used actuator in the position of the complex objective lens formed by object lens 27 and hologram lens 26 according to the focus servo signal adjustment.Because 26 pairs of first-order diffraction light of hologram lens play the concavees lens effect, the difference between focal point S1, the S2 rises to about 1mm.
Therefore, even transmitted light L4 and first-order diffraction light L5 are assembled by object lens 27 simultaneously, under the condition of the alternate position spike between focal point S1, the S2 in 50 μ m to 1mm scopes, just can not produce harmful effect to recording of information or reproduction.
The example that imaging optical system 21 is used for various CDs is described now.
Be used for a kind of optical disc apparatus at imaging optical system 21, only reproduction is recorded under the situation of the message segment in slim high density compact disc and the thick type compact-disc in this optical disc apparatus, and hologram lens 26 are set as the diffraction efficiency that incident light L3 becomes diffraction light L5 from about scope of 20% to 70%.In this case, the intensity that is focused at the transmitted light L4 on the high density compact disc almost be focused at CD on the intensity of first-order diffraction light L5 identical.Thereby it is minimum that the output power of incident light L3 can reduce to.
Moreover, be used for a kind of optical disc apparatus at imaging optical system 21, in this optical disc apparatus, record or reproduction be recorded in the slim high density compact disc message segment and only reproduction be recorded under the situation of the message segment in the thick type CD, the diffraction efficiency that hologram lens 26 become first-order diffraction light L5 to incident light L3 is set as and is equal to or less than 30% value.In this case, even record one segment information needs high-intensity transmitted light L4 on high density compact disc, also can not increase the intensity of incident light L3 and realize recording of information reliably, because the efficiency of transmission of 26 couples of incident light L3 of hologram lens is very high.In other words, when a segment information is recorded on the high density compact disc, can improve the utilization factor of incident light L3, so that the output power of incident light L3 can reduce to minimum.
In first embodiment, 26 pairs of first-order diffraction light of hologram lens L5 plays the concavees lens effect.Yet, can suitably use hologram lens 26M to replace hologram lens 26 to first-order diffraction light L5 blistering lensing.In other words, as shown in Fig. 9 A, 9B, diffraction light L5 is focused on the first information medium 23 forming diffraction limited focal point S1 by object lens 27, and transmitted light L4 is focused on second information medium 25 to form diffraction limited focal point S2 by object lens 27.In this case, consider the range of movement of actuator, require the alternate position spike between focal point S1, the S2 to be equal to or less than 0.5mm.Yet, in imaging optical system 21M, use the hologram lens 26M that diffraction light L5 is played the concavees lens effect, can prevent the appearance of aberration.Describe the achromatism function in the imaging optical system in detail.
When using f H0Represent hologram lens 26M to having wavelength X 0Incident light L3 focal length and use f H1Represent hologram lens 26M to having wavelength X 1Another focal length of incident light L3 the time, satisfy formula (2).
f H1＝f H0×λ 0/λ 1(2)
Along with the wavelength X of incident light L3 is elongated, the focal distance f of hologram lens 22 HShorten.Moreover, when using n (λ 0) represent 27 pairs on object lens to have wavelength X 0Incident light L3 refractive index and with n (λ 1) represent 27 pairs on object lens to have wavelength X 1Another refractive index of incident light L3 the time, 27 pairs on object lens have the focal distance f of the incident light L3 of wavelength X D(λ) express with formula (3).
f D(λ 1)＝f D(λ 0)×(n(λ 0)-1)/(n(λ 1)-1)--(3)
Along with the wavelength X of incident light L3 is elongated, the focal distance f of object lens 27 D(λ) lengthening.In other words, object lens 27 mid-focal length f D(λ) to the correlationship and the hologram lens 26M mid-focal length f of wavelength X HCorrelationship to wavelength X is opposite.Thereby the complex objective lens 29M that is made up of object lens 27 and hologram lens 26M plays the condition of achromat effect to be expressed by equation (4).
1/f H0+1/f D(λ 0)＝1/f H1+1/f D(λ 1)＝1/(f H0×λ 0/λ 1)+(n(λ 1)-1)/{f D(λ 0)×(n(λ 0)-1)}---(4)
Therefore, because object lens 27 mid-focal length f D(λ) opposite with relation among the hologram lens 26M to the correlationship of wavelength X, scioptics 26M, 27 combination can form the complex objective lens 29M with achromatism function, and can prevent the appearance of aberration.Moreover, even strictly do not satisfy equation (4), also can suppress the appearance of aberration greatly.
Moreover because hologram lens 26M is to first-order diffraction light L5 blistering lensing, the curvature of object lens 27 can be very little.Moreover, because hologram lens 26M is a planar device, the light-duty complex objective lens that can have the achromatism function with the mass production method manufacturing.Anaberrational principle is at first document (D.Faklis and M.Morris, photonics spectrum (1991), 131 pages of 205 pages of November and Dec), second document (people such as M.A.Gan, photo-optics Instrumentation Engineering Shi Xuehui (1991), the 1507th volume, 116 pages) and the 3rd document (P.T ω ardo ω ski and P.Meirueis, photo-optics Instrumentation Engineering Shi Xuehui (1991), the 1507th volume, 55 pages) the middle proposition.
(second embodiment)
Figure 10 A is the constitutional diagram that has according to the imaging optical system of the complex objective lens of the second embodiment of the present invention, and the transmitted light of a branch of no diffraction is focused on the slim information medium.Figure 10 B is the constitutional diagram of imaging optical system shown in Figure 10 A, and a branch of first-order diffraction optical convergence is on thick type information medium.
As Figure 10 A, shown in the 10B, one be used for an optical convergence on second substrate 24 of first substrate 22 of first information medium 23 (thickness T 1) or second information medium 25 (thickness T 2) so that form the imaging optical system 31 of diffraction limited focal point, comprise that one is used for without any the part of diffraction ground transmission incident light with the remainder that forms a branch of transmitted light L4 and diffraction incident light L3 forming the blazed hologram lens 32 of a branch of first-order diffraction light L5, and be used for transmitted light L4 is focused on the first information medium 23 or first-order diffraction light L5 is focused at object lens 27 on second information medium 25.
By in the graph area 32A of transparent substrate 28, forming holographic lens 32 with the concentric circles raster graphic P2 that draws.Graph area 32A is positioned at the middle part of transparent substrate 28.The diameter of raster graphic P2 is equal to or greater than the aperture of object lens 27.Moreover, 32 pairs on hologram lens through the diffraction efficiency of the incident light L3 of raster graphic P2 transmission with first embodiment in identical mode less than 100% so that the intensity of transmitted light L4 be enough to or from first information medium 23 records or reappear a segment information.
In addition, very high in the diffraction efficiency at the middle part of graph area 32A as shown in Figure 11, and also diffraction efficiency reduces gradually along the direction outwardly of graph area 32A.In other words, form under the situation of embossment at the raster graphic P2 of hologram lens 32, the height H of embossment reduces gradually along the direction outwardly of graph area 32A among the raster graphic P2.In other words, glitter shape approximation under the situation of stairstepping in the ideal of hologram lens 26, the every raster graphic P2 that is positioned at transparent substrate 28 cores forms the stairstepping shown in Figure 12 A, the oblique angle Q of step in Figure 12 A 1Big and between the first etched width W1 and the second etched width W2, satisfy relational expression W1＞W2, and the raster graphic P2 that forms stairstepping shown in Figure 12 A changes gradually, way is that the direction outwardly along graph area 32A reduces the first etched width W1 and strengthens the second etched width W2, reduces the height H of graph area P2 simultaneously gradually.Thereby the every raster graphic P2 that is positioned at the peripheral part of transparent substrate 28 forms the stairstepping shown in Figure 12 B, and the oblique angle Q2 of step is little and satisfy relational expression W1＜W2 between the first etched width W1 and the second etched width W2 in Figure 12 B.Moreover every raster graphic P2 of the center section between core and peripheral part forms the stairstepping shown in Figure 12 C, and etched width W1, W2 are identical in Figure 12 C.
In the above structure of imaging optical system 31, forming a branch of transmitted light L4, and transmitted light L4 is assembled by object lens 27 part of incident light L3 without any 32 transmissions of diffraction ground warp hologram lens.Moreover the remainder of incident light L3 is by hologram lens 32 diffraction and refraction.In this case, 32 couples of incident light L3 of hologram lens play the concavees lens effect, so that first-order diffraction light L5 disperses from hologram lens 32.After this, first-order diffraction light L5 is assembled by object lens 27.
Slim first information medium 23 be used for or under the situation of the front surface of medium 23 record or reproduction message segment, as shown in Figure 10 A, transmitted light L4 is incident on the rear surface of first information medium 23 and by object lens 27 and focuses on the first information medium front surface so that form diffraction limited focal point S3 on first information medium 23.In this case, because the diffraction efficiency in the core of raster graphic P2 is high and owing to the outwardly direction of diffraction efficiency along raster graphic P2 reduces gradually, the diffraction probability of incident light L3 reduces in the peripheral part of raster graphic P2.Thereby light L4 is through object lens 27 transmissions under the big condition of the numerical aperture NA of object lens 27.
Different therewith, thick type second information medium 25 be used for or under the situation of the front surface of medium 25 record or reproduction message segment, diffraction light L5 is incident on the rear surface of second information medium 25 and is focused on the front surface of second information medium 25 so that form diffraction limited focal point S4 on second information medium 25.In this case, because 32 concavees lens works of hologram lens even the thickness T 1 of first information medium 23 is different from the thickness T 2 of second information medium 25, also can form diffraction limited focal point S3, S4 in order to disperse first-order diffraction light L5.Thereby in fact the complex objective lens of being made up of hologram lens 32 and object lens 27 34 has two focuses.
Therefore and since light L4 under the big condition of the numerical aperture NA of object lens 27 through object lens 27 transmissions, the intensity that is focused at the transmitted light L4 on the first information medium 23 can be very high.
Moreover under the situation of incident light L3 by the semiconductor laser emission, the far-field pattern of incident light 13 distributes by the Gaussian distribution as shown in Figure 13 A.Thereby owing to the outwardly direction of diffraction efficiency along raster graphic P2 reduces gradually, the far-field pattern of transmitted light L4 is pressed the gentle slope distribution of shapes shown in Figure 13 B.Different with second embodiment, because incident light L3 is not diffracted at the no graph area 26B of hologram lens 26 in first embodiment, the intensity of transmitted light L4 increases suddenly in the peripheral part of hologram lens 26.
Therefore, compare with first embodiment, the secondary maximum that is focused at the transmitted light L4 on the focal point S3 in a second embodiment can further suppress.In other words, utilize imaging optical system 31 can realize recording of information and reproduction and to information without any destruction.
In addition, under first-order diffraction light L5 is focused on second information medium 25 with the situation that forms diffraction limited focal point S4, the numerical aperture of 27 pairs of first-order diffraction light of object lens L5 is little, because the diffraction efficiency of hologram lens 32 is along the reduction of direction outwardly of graph area 32A.As a result, the intensity step-down of first-order diffraction light L5.Improve the diffraction efficiency of hologram lens 32 herein so that under the situation of the intensity of raising first-order diffraction light L5, the transmitted light L4 intensity of light beam part within it greatly reduces, and the secondary maximum (or side wave lobe) of transmitted light L4 on focal point S3 strengthens odiously.Thereby the incident light L3 that its far-field pattern distributes by Gaussian distribution does not have any increase of secondary maximum with the intensity that improves first-order diffraction light L5 to 32 emissions of hologram lens.In detail, as shown in Figure 14 A, the incident light L3 that not only is distributed in the core of Gaussian distribution but also is distributed in the peripheral part of Gaussian distribution reflects through 32 transmissions of hologram lens and by object lens 27, because the diameter of raster graphic P2 is equal to or greater than the aperture of object lens 27.Thereby object lens 27 become big than among first embodiment in light source side to the numerical aperture NA of incident light L3, and have improved the diffraction efficiency of hologram lens 32.As a result, the intensity that is focused at the first-order diffraction light L5 on second information medium 25 can improve, as shown in Figure 14 B.Moreover, because very low and because the diffraction efficiency of hologram lens 32 increases along the direction of raster graphic district 32A, the intensity of transmitted light L4 is by the gentle slope distribution of shapes as shown in Figure 14 C in the intensity of the peripheral part of Gaussian distribution incident light L3.Therefore, the secondary maximum at the transmitted light L4 of focal point S3 place can be suppressed.
The example that imaging optical system 31 is used for various CDs is described.
Be used for a kind of like this optical disc apparatus at imaging optical system 31, at this optical disc apparatus, only reproduction is recorded under the situation of the message segment in slim high density compact disc and the thick type compact-disc, and the diffraction efficiency of 32 couples of incident light L3 of hologram lens is set as from about scope of 20% to 70%.In this case, the intensity that is focused at the transmitted light L4 on the high density compact disc almost be focused at compact-disc on the intensity of first-order diffraction light L5 identical.Thereby it is minimum that the output power of incident light L3 can reduce to.
Moreover, be used for a kind of like this optical disc apparatus at imaging optical system 31, at this optical disc apparatus, the record or the reproduction be recorded in the slim high density compact disc message segment and only the reproduction be recorded under the situation of the message segment in the thick type CD, the diffraction efficiency of 32 couples of incident light L3 of hologram lens is set as and is equal to or less than 30% value.In this case, even record one segment information needs high-intensity transmitted light L4 on high density compact disc, also can not increase the intensity of incident light L3 and realize recording of information reliably, because the efficiency of transmission of 32 couples of incident light L3 of hologram lens is very high.In other words, when a segment information is recorded on the high density compact disc, can improve the utilization factor of incident light L3, so that the output power of incident light L3 can reduce to minimum.
In a second embodiment, the raster graphic P2 that is positioned at transparent substrate 28 middle parts becomes the stairstepping shown in Figure 12 B from the stairstepping shown in Figure 12 A via the stairstepping shown in Figure 12 C gradually along the direction outwardly of graph area 32A.Yet, because raster graphic P2 forms the stairstepping shown in Figure 12 C in transparent substrate 28, can prevent the appearance of the unnecessary diffraction light of negative first-order diffraction light and so on effectively at the center section of transparent substrate 28, preferably center section occupies most of graph area 32A of hologram lens 32.In this case, the intensity of transmitted light L4 and diffraction light L5 and can be maximum, so that can improve the utilization factor of incident light L3.
Moreover, because the first etched width W1 of raster graphic P2 reduces gradually along the direction outwardly of graph area 32A, when first width W 1 was reduced to value less than 1 μ m, the raster graphic P2 that forms the stairstepping shown in Figure 12 B can suitably become the stairstepping shown in Figure 12 D.In other words, one section four step shown in Figure 12 B becomes one section two step.In this case, the raster graphic P2 of the stairstepping shown in formation Figure 12 D can be easy to make.In addition, under the situation that the height H 4 that forms the raster graphic P2 of stairstepping shown in Figure 12 D further reduces along the direction outwardly of graph area 32A, raster graphic P2 is preferably formed as the stairstepping shown in Figure 12 E.In other words, when the height H 5 of raster graphic P2 reduced, the 3rd etched width W3 reduced gradually along the direction outwardly of graph area 32A.Thereby the diffraction efficiency of hologram lens 32 can reduce along the direction outwardly of graph area 32A and gradually without any the manufacturing difficulty of raster graphic P2.
In addition, as shown in Figure 15 A, the raster graphic P1 of graph area 32A can be set by the core at transparent substrate 28 and four kinds of diffraction zone 33A, 33B, 33C and 33D around raster graphic P1 are set, replace hologram lens 32 and form hologram lens 33.Through the diffracted efficiency of transmission of a part of incident light L3 of each diffraction zone 33A to 33D transmission with control hologram lens 33.In this case, transmitted light L4 is in the strength degradation of its peripheral part, and the inferior maximum that consequently appears at focal point S3 is suppressed.Moreover the raster graphic P1 of hologram can change raster graphic P2 into.Moreover the grating orientation of diffraction zone 33A to 33D can be different.In this case, even the first-order diffraction light L5 of diffraction is after diffraction light L5 is by the reflection of second information medium 25 such as be incident on the 33C of diffraction zone in the 33A of diffraction zone, the diffraction light L5 of diffraction does not pass abreast with optical axis once more in the 33C of diffraction zone.Thereby, in detector, detect the segment information read from second information medium 25 with the situation that reappears this information under, the first-order diffraction light L5 of diffraction is not detected device as diffused light and surveys in the 33A to 33D of diffraction zone.Therefore, the reproduction of information is not destroyed.
Moreover as shown in Figure 15 B, holographic Figure 32 can be suitable for the blistering lensing.In this case, diffraction light L5 is focused on the first information medium 23, and transmitted light L4 is focused on second information medium 25, as shown in Figure 15 C.
(the 3rd embodiment)
Figure 16 A is the constitutional diagram that has according to the imaging optical system of the complex objective lens of the third embodiment of the present invention, and a branch of first-order diffraction optical convergence is on slim information medium.Figure 16 B is the constitutional diagram of imaging optical system shown in Figure 16 A, and the transmitted light of a branch of no diffraction is focused on the thick information medium.
As Figure 16 A, shown in the 16B, being used for an optical convergence comprises that with the imaging optical system 41 that forms the diffraction limit focal point one is used for without any the part of diffraction ground transmission incident light L3 with the remainder that forms a branch of transmitted light L4 and diffraction incident light L3 forming the blazed hologram lens 42 of a branch of first-order diffraction light L6 on second substrate 24 of first substrate 22 of first information medium 23 (thickness T 1) or second information medium 25 (thickness T 2), and is used for first-order diffraction light L6 is focused on the first information medium 23 or transmitted light L4 is focused at object lens 27 on second information medium 25.
By in the graph area 42A of transparent substrate 28, forming hologram lens 42 with the concentric circles raster graphic P3 that draws.Graph area 42A is positioned at the core of transparent substrate 28.The diameter of raster graphic P3 is equal to or greater than the aperture of object lens 27.Moreover, 42 pairs on hologram lens through the diffraction efficiency of the incident light L3 of raster graphic P3 transmission with first embodiment in identical mode less than 100% so that the intensity of transmitted light 14 be enough to or from second information medium, 25 records or reappear a segment information.
In addition, as shown in Figure 17, hologram lens 42 are very high in the diffraction efficiency of the peripheral part of graph area 42A, and diffraction efficiency reduces gradually along the direction inwardly of graph area 42A.In other words, form under the situation of embossment at the raster graphic P3 of hologram lens 42, the height H of embossment reduces gradually along the direction inwardly of graph area 42A among the raster graphic P3.In other words, glitter shape approximation under the situation of stairstepping in the ideal of hologram lens 26, the every joint raster graphic P3 that is positioned at the peripheral part of transparent substrate 28 forms the stairstepping shown in Figure 12 A, the oblique angle Q of step in Figure 12 A 1Big and the first and second etched width W1, W2 satisfy relational expression W1＞W2, the raster graphic P3 that forms stairstepping shown in Figure 12 A gradually changes, way is that the direction inwardly along graph area 42A reduces the first etched width W1 and strengthens the second etched width W2, reduces the height of raster graphic simultaneously gradually.Thereby the every joint raster graphic P3 that is positioned at the core of transparent substrate 28 forms the stairstepping shown in Figure 12 B, the oblique angle Q of step in Figure 12 B 2Little and satisfy relational expression W1＜W2.Moreover every joint raster graphic P3 of the center section between center and peripheral part forms the stairstepping shown in Figure 12 C, and etched width W1, W2 are identical in Figure 12 C.
In the above structure of imaging optical system 41, as shown in Figure 16 B, forming a branch of transmitted light L4, and lens light L4 is assembled by object lens 27 part of incident light L3 without any 42 transmissions of diffraction ground warp hologram lens.Moreover, the remainder of incident light L3 by hologram lens 42 diffraction to form a branch of first-order diffraction light L6.In this case, 42 couples of incident light L3 of hologram lens blistering lensing, so that the first-order diffraction light L6 in hologram lens 42 assembles.After this, diffraction light L6 is assembled by object lens 27.
Slim first information medium 23 be used for or under the situation of the front surface of medium 23 record or reproduction message segment, as shown in Figure 16 A, diffraction light L6 is incident on the rear surface of first information medium 23 and focuses on its front surface so that form diffraction limited focal point S5 on first information medium 23.Different therewith, thick type second information medium 25 be used for or under the situation of the front surface of medium 25 record or reproduction message segment, transmitted light L4 is incident on the rear surface of second information medium 25 and focuses on its front surface so that form diffraction limited focal point S6 on second information medium 25.
In this case, because hologram lens 42 work the convex lens effect of assembling diffraction light L6,, also form diffraction limited focal point S5, S6 even the thickness T 1 of first information medium 23 is different from the thickness T 2 of second information medium 25.Thereby in fact the complex objective lens of being made up of hologram lens 42 and object lens 27 43 has two focuses.
Moreover because 42 couples of diffraction light L6 of hologram lens blistering lensing, diffraction light L6 is through object lens 27 transmissions under the in fact big condition of the numerical aperture NA of object lens 27.
In addition because the diffraction efficiency in the peripheral part of raster graphic P3 is very high and since diffraction efficiency reduce gradually along the direction inwardly of raster graphic P3, higher at the diffraction probability of the peripheral part of raster graphic P3 incident light L3.
The raster graphic P3 of hologram lens 42 is designed to revise in object lens 27 and first information medium 23 any aberration that occurs, thus diffraction light L6 through having thickness T 1 23 transmissions of first information medium and be focused on the medium 23 so that without any aberration ground formation diffraction limited focal point S5.A kind of method for designing with hologram lens 42 of aberration debugging functions has been described.
After diffraction light L6 was focused on the first information medium 23, spherical wave was dispersed and through first substrate 22 and object lens 27 transmissions from focal point S5.After this, spherical wave through transparent substrate 28 transmissions and with incident light L3 optical interference.Thereby, form conoscope image by the interference between spherical wave and the incident light L3.Can calculate conoscope image by the antiphase addition that the phase place of spherical wave and paraphase incident light L3 phase place are obtained.Therefore, can be easy to form the raster graphic P3 of the hologram lens 42 that meet the conoscope image of calculating according to the computer-generated hologram method.
Therefore, because 42 pairs of first-order diffraction light of hologram lens L6 blistering lensing, the curvature of object lens 27 can reduce.Moreover, make the glass material that object lens 27 do not need to have high index of refraction.
Moreover because the first-order diffraction light L6 that forms in hologram lens 42 assembled before diffraction light L6 incident object lens 27, the distance along optical axis direction between focal point S5, the S6 can be lengthened to about 1mm.Thereby, be focused at that focal point S6 (or S5) goes up so that record or when reading a segment information even transmitted light L4 (or first-order diffraction light L6) focuses on, light L6 (or L4) also out-focus is focused at focal point S6 (or S5) and goes up so that reduce the intensity that L6 (or L4) locates at focal point S6 (or S5).Thereby, recording of information or reproduction there are not harmful effect.
Moreover, because 42 pairs of first-order diffraction light of hologram lens L6 blistering lensing can prevent the generation of aberration in imaging optical system 41.In detail, the focal length of hologram lens 42 is elongated and shorten along with incident light L3 wavelength.Different therewith, the focal length of object lens 27 is elongated and extend along with incident light L3 wavelength.In other words, object lens 27 mid-focal lengths are opposite to the dependence of wavelength with hologram lens 42 mid-focal lengths to the dependence of wavelength.Thereby the combination of scioptics 27,42 can form the complex objective lens 43 with achromatism function, and can prevent the generation of aberration.
Moreover, because hologram lens 42 are planar devices, so can make light-duty complex objective lens by extensive manufacture.
Moreover because the diffraction efficiency of hologram lens 42 reduces gradually along the direction inwardly of graph area 42A, in fact the numerical aperture of 27 pairs of first-order diffraction light of object lens L6 becomes big.Thereby, the intensity of first-order diffraction light L6 can strengthen in case or from first information medium 23 record or reappear a segment information.
Moreover under the situation of semiconductor laser emission, the far-field pattern of incident light L3 distributes by the Gaussian distribution as shown in Figure 13 A at incident light L3.Thereby because the diffraction efficiency of hologram lens 42 reduces gradually along the direction inwardly of raster graphic P2, the far-field pattern of first-order diffraction light L6 is by the gentle slope distribution of shapes.Therefore, being focused at the secondary maximum of the first-order diffraction light L6 on the focal point S5 can be than further being suppressed in first embodiment in the 3rd embodiment.In other words, can realize recording of information and reproduction without any destroying ground to information with imaging optical system 41.
In addition, under transmitted light L4 was focused on second information medium 25 with the situation that forms diffraction limited focal point S6, the numerical value footpath of 27 couples of transmitted light L4 of object lens was little, because the diffraction efficiency of hologram lens 42 increases along the direction outwardly of raster graphic 42A.As a result, the intensity step-down of transmitted light L4.Under the situation of the efficiency of transmission that improves hologram lens 42 with the intensity of increasing transmitted light L4, the first-order diffraction light L6 intensity of light beam part within it reduces greatly, and the secondary maximum (or side wave lobe) of first-order diffraction light L6 at focal point S6 place odiously strengthens.Thereby the incident light L3 that its far-field pattern distributes by Gaussian distribution does not have any increase of secondary maximum with the intensity that improves transmitted light L4 to 42 emissions of hologram lens.In detail, as shown in Figure 18 A, the incident light L3 that not only is distributed in the core of Gaussian distribution but also is distributed in the peripheral part of Gaussian distribution reflects through 42 transmissions of hologram lens and by object lens 27, because the diameter of raster graphic P3 is equal to or greater than the aperture of object lens 27.Thereby object lens 27 become greater than the numerical aperture in first embodiment at the numerical aperture NA of light source side to incident light L3, and have improved the efficiency of transmission of hologram lens 42.As a result, the intensity that is focused at the transmitted light L4 on second information medium 25 can improve, as shown in Figure 18 B.Moreover, because the intensity of incident light L3 in the peripheral part of Gaussian distribution is low and because the diffraction efficiency of hologram lens 42 reduces along the direction inwardly of raster graphic 42A, first-order diffraction light L6 is by the gentle slope distribution of shapes, as shown in Figure 18 C.Therefore, first-order diffraction light L6 can be suppressed in the secondary maximum at focal point S5 place.
The example that imaging optical system 41 is used for various CDs is now described.
Be used for such optical disc apparatus, this optical disc apparatus at imaging optical system 41 and only reappear under the situation that is recorded in the message segment among slim high density compact disc and the thick type CD, the diffraction efficiency of 42 couples of incident light L3 of hologram lens is set as in about scope of 20% to 70%.In this case, the intensity that is focused at the transmitted light L4 on the CD almost be focused at high density compact disc on the intensity of first-order diffraction light L6 identical.Thereby it is minimum that the output power of incident light L3 can reduce to.
Moreover, imaging optical system 41 be used for such optical disc apparatus, this device record or reproduction be recorded in the slim high density compact disc message segment and only reproduction be recorded under the situation of the message segment in the thick type CD, the diffraction efficiency of 42 couples of incident light L3 of hologram lens is set as and is equal to or greater than 55% value.In this case, even record one segment information needs high-intensity first-order diffraction light L6 on high density compact disc, the intensity that does not improve incident light L3 also can realize recording of information reliably, because hologram lens 42 are very high the diffraction efficiency that incident light L3 becomes first-order diffraction light L6.In other words, when record one segment information on high density compact disc, can improve the utilization factor of incident light L3, so that the output power of incident light L3 can reduce to minimum.Moreover because the diffraction efficiency of hologram lens 42 reduces gradually along the direction inwardly of graph area 42A, in fact the numerical aperture of 27 pairs of first-order diffraction light of object lens L6 becomes big.Thereby, the intensity of first-order diffraction light L6 can improve in case or from high density compact disc record or reappear a segment information.
In the 3rd embodiment, the raster graphic P3 that is arranged in the graph area 42A of transparent substrate 28 becomes the stairstepping shown in Figure 12 A from the stairstepping shown in Figure 12 B via the stairstepping shown in Figure 12 C gradually along the direction outwardly of graph area 42A, strengthens the height H of raster graphic P3 simultaneously.Yet, because the raster graphic P3 center section that forms the transparent substrate 28 of the stairstepping shown in Figure 12 C can prevent the generation of the unnecessary diffraction light of negative first-order diffraction light of picture and so on effectively therein, so preferably center section occupies most of graph area 42A of hologram lens 42.In this case, the intensity of transmitted light L4 and first-order diffraction light L6 can be maximum, so that can improve the utilization factor of incident light L3.
Moreover, because the first etched width W1 of raster graphic P3 reduces gradually along the direction inwardly of graph area 42A, when first width W 1 was reduced to value less than 1 μ m, the raster graphic P3 that forms the stairstepping shown in Figure 12 B became the stairstepping shown in Figure 12 D.In this case, the raster graphic P3 that forms the stairstepping shown in Figure 12 D can easily make.In addition, under the situation that the height H 4 of the raster graphic P3 that forms the stairstepping shown in Figure 12 D further reduces along the direction inwardly of graph area 42A, preferably raster graphic P3 forms the stairstepping shown in Figure 12 E.In this case, the 3rd etched width W3 reduces gradually along the direction inwardly of graph area 42A, reduces the height H 5 of raster graphic P3 simultaneously.Thereby, the diffraction efficiency of hologram lens 42 can reduce gradually along the direction inwardly of graph area 42A and the manufacturing of raster graphic P3 without any difficulty.
In first to the 3rd embodiment of imaging optical system 21,31 and 41, hologram lens 26,32 and 42 raster graphic P1, P2 and P3 be not forming in the face of on the front side of object lens 27 at transparent basal plane 28 respectively.Thereby, can not produce harmful effect to recording of information or reproduction at a branch of light of the preceding lateral reflection of transparent substrate 28 as diffused light.In detail, because reflected light is by hologram lens diffraction, reflected light is scattered.Moreover even first-order diffraction light L5 or L6 are reflected at the rear side place of transparent substrate 28, the diffraction light that is reflected is also once more by hologram lens diffraction and scattering.Thereby, in the front side of hologram lens or the light of back lateral reflection recording of information or reproduction are not produced harmful effect.
Yet, cover under the situation of one deck antireflection film at this place not forming raster graphic on the front side of hologram lens 28, hologram lens 26,32 and 42 raster graphic P1, P2 and P3 be forming in the face of on the rear side of object lens 27 at transparent substrate 28 respectively.In this case, because first-order diffraction light L5, L6 be in the refraction of place, the front side of hologram lens 28, imaging optical system 21,31 and 41 design can be simplified.
Moreover in first to the 3rd embodiment, hologram lens 26,32 and 42 raster graphic P1, P2 and P3 form embossment respectively so that make phase modulation-type hologram lens.Yet as disclosing No. 189504/86 (clear and 61-189504) and disclosing described in No. 241735/88 (clear and 63-241735) temporarily, phase modulation-type hologram lens can be made with liquid crystal cell (cell) temporarily.Moreover phase modulation-type hologram lens can be made with the birefringent material as lithium niobate and so on.For example, phase modulation-type hologram lens can be by making the proton exchange of lithium niobate substrate surface portion.
(the 4th embodiment)
Moreover in first to the 3rd embodiment, the complex objective lens 29,34 or 43 with two focuses is made up of object lens 27 and hologram lens 26,32 or 42.Yet, as complex objective lens according to the 4th embodiment shown in Figure 19 A, the most handy packaging system 44 each hologram lens 26,32 and 42 and object lens 27 lanes be integral forming a complex objective lens 45, in this complex objective lens each hologram lens 26,32 and 42 and object lens 27 between relative position fix.In this case, can be focused at transmitted light L4 and first-order diffraction light L5, L6 on first or second information medium 23,25 at an easy rate by the position of adjusting packaging system 44 with actuator.Moreover, as another complex objective lens according to the 4th embodiment that revises shown in Figure 19 B, preferably each raster graphic P1, P2 and P3 directly be drawn in object lens 27 in the face of on the curved surface of light source side to form a complex objective lens 46, each hologram lens 26,32 and 42 form integral body with object lens 27 in object lens 46.
Therefore, the central shaft of object lens 27 can be consistent with the central shaft of each hologram lens 26,32 and 42 all the time, so that can prevent to occur as each hologram lens 26,32 of comatic aberration and astigmatic aberration and so on and 42 off-axis aberration in first-order diffraction light in the 4th embodiment.And because hologram lens 26,32 or 42 are arranged on the lens surface of object lens 27, this surperficial curvature is higher than the curvature on the other lenses surface of object lens 27, thereby the sine condition that the hologram lens are counted as lens can satisfy at an easy rate.Therefore, since the aberration degree that the formation error of optical head device is produced can be reduced effectively.
(the 5th embodiment)
Moreover, as complex objective lens according to the 5th embodiment shown in Figure 20, preferably each raster graphic P1, P2 and P3 directly be drawn in object lens 27 in the face of on the side of information medium 23 or 25 to form a complex objective lens 47, each hologram lens 26,32 and 42 form integral body with object lens 27 in object lens 47.In this case, the curvature on object lens 27 sides can be very little or be flat shape.Thereby, can make each raster graphic P1, P2 and P3 with low cost.Moreover, causing from inclined light shaft under the situation of aberration by the hologram lens, can prevent aberration by the light source of hologram lens and incident light L3 is fixed on the same pedestal.
(the 6th embodiment)
Contrast Figure 21 to 26 describes and to have the complex objective lens 29 shown in first to the 5th embodiment, 29M, 34,43,45, an optical head device of 46 and 47 according to sixth embodiment of the invention.X shown in Figure 21 to 26, Y are identical with the Z coordinate.
Figure 21 is the constitutional diagram according to the optical head device of the 6th embodiment.
As shown in Figure 21, a kind of be used for or comprise the light source 52 of a picture semiconductor laser and so on that is used for emitting incident light L3 from the optical head device 51 of information medium 23 or 25 records or reproduction message segment, a collimation lens 53 that is used for collimating incident light L3, one is used at transmission incident light L3 on the emitting light path and at transmitted light L4R or a branch of beam splitter 54 by diffraction light L5R (or L6R) that information medium 23 or 25 on reflection diffracting light L5 (or L6) form of reflects one on the input path by forming at reflection and transmission light L4 on information medium 23 or 25, one by hologram lens 26 (or 26M, 32,33 or 42) and complex objective lens 29 (or the 29M that forms of object lens 27,34,43,45,46 or 47), one is used for assembling by the transmitted light L4R of beam splitter 54 reflections or the condenser 55 of diffraction light L5R, wave front that is used for changing transmitted light L4R or diffraction light L5R is with the wave front modifier 56 of image hologram of a plurality of focal points of forming transmitted light L4R or diffraction light L5R and so on, the intensity of a focal point that is used for surveying transmitted light L4R that its wave front changed by ripple battle array modifier 56 or diffraction light L5R is with the photodetector 57 of the servosignal that obtains being recorded in information signal on information medium 23 or 25 and image focu error signal and tracking error signal and so on, and is used for moving according to servosignal the actuating unit 58 of the complex objective lens of being made up of hologram lens 26 and object lens 27.
In above structure, a branch of incident light L3 from light source 52 emission collimates collimation lens 53 and through beam splitter 54 transmissions.After this, the part of incident light L3 is without any 29 transmissions of diffraction ground warp complex objective lens, and the remainder of incident light L3 is diffracted.
After this, or from first information medium 23 record or reappear under the situation of a segment information, transmitted light L4 is focused on the first information matchmaker complete 23 to form the first focal point S1.In other words, transmitted light L4 is incident on the rear surface of first information medium 23, and forms the first focal point S1 on the front surface of first information medium 23.After this, a branch of transmitted light L4R in the reflection of the front surface place of first information medium 23 passes same light path in opposite direction.In other words, a part of transmitted light L4R reflects through complex objective lens 29 transmissions and by beam splitter 54 once more without any diffraction ground.In this case, transmitted light L4R is aligned.After this, transmitted light L4R is assembled by condenser 55, and the wave front of most of transmitted light L4R is changed so that form a plurality of focal points on photodetector 57.After this, the focal point intensity of transmitted light L4R is detected in photodetector 57.Thereby, obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.Actuating unit 58 is operated so that with high-speed mobile complex objective lens 29 according to servosignal, so that transmitted light L4 focusing is focused on the first information medium 23.
Moreover, or from second information medium 25 record or reappear under the situation of a segment information, diffraction light L5 is focused on second information medium 25 to form the second focal point S2.In other words, diffraction light L5 is incident on the rear surface of second information medium 25, and forms the second focal point S2 on the front surface of second information medium 25.After this, a branch of diffraction light L5R in the reflection of the front surface place of second information medium 25 passes same light path in opposite direction.In other words, a part of diffraction light L5R reflects by hologram lens 26 diffraction and by beam splitter 54 once more.In this case, diffraction light L5R is collimated.After this, diffraction light L5R is assembled by condenser 55, and the wave front of most of diffraction light L5R is changed so that form a plurality of focal points on photodetector 57.In this case, be incident on the condenser 55 diffraction light L5R by be incident on condenser 55 on the identical mode of transmitted light L4R aim at, the focal point of diffraction light L5R forms on identical position with the focal point of transmitted light L4R.After this, the intensity of the focal point of diffraction light L5R is detected in photodetector 57.Thereby, obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.Actuating unit 58 is according to the servosignal operation, so that with high-speed mobile complex objective lens 29, so that diffraction light L5 focusing is focused on second information medium 25.
In this case, since transmitted light L4R once more without any the complex objective lens transmission of diffraction ground warp diffraction light L5R once more by hologram lens 26 diffraction, even focal point S1 is different from focal point S2, information medium 23 or 25 with beam splitter 54 between scope in emitting light path also consistent with input path.Thereby, its glazing L4R on the photodetector 57 or L5R are not pressed mirror image by the focal point S7 of wave front modifier 56 diffraction and are assembled with respect to the launching site of light source 52, so that are not converged at same focal point S7 by the light L4R of wave front modifier 56 diffraction and L5R.In like manner, be focused at another same focal point by the light L4R of wave front modifier 56 diffraction and L5R.
Therefore, even complex objective lens has two focuses, the intensity that wave front modifier 56 that the intensity of detection transmitted light L4R is required and photodetector 57 also can be used for surveying diffraction light L5R.Thereby, making optical head device 51 required part numbers can reduce, actually no matter or and both made information medium thick thin and with luminosity head unit 51 or during from information medium record or reproduction message segment, also can make undersized optic probe device with low cost and light weight.
Form under the whole situation with object lens 27 as shown in Figure 19 A, 19B or 20 at hologram lens 26 (or 32,33,42), each complex objective lens 45,46 and 47 can be with the light weight manufacturing, because hologram lens 26 (or 32,33,42) are planar optics elements.For example, the weight of hologram lens 26 (or 32,33,42) is less than tens milligrams.Thereby, form whole hologram lens 26 with object lens 27 and can be performed device 58 at an easy rate and move.
Next the detection method of servosignal is described.Figure 22 is by the planimetric map of front modifier 56.Figure 23 is the first-order diffraction light of detection in photodetector 57 and the enlarged drawing of transmitted light.As shown in Figure 22, wave front modifier 56 is divided into a diffraction light generation district 56a and a pair of diffraction light generation district 56b, a 56c who is wherein drawing a pair of raster graphic P5, P6 who is wherein drawing raster graphic P4.The light L4R or the L5R that are incident on the diffraction light generation district 56a are diffracted to obtain focus error signal.The light L4R or the L5R that are incident on each diffraction light generation district 56b, 56c are diffracted to obtain tracking error signal.
Originally, as the example of focus error signal detection method the spot definition determination method that is used for surveying focus error signal is described.This method proposed in Japanese patent application nineteen ninety No. 185722.Briefly, under the situation of this method of employing, permission rigging error in the optical head device can strengthen significantly, even and the servosignal that also can stably obtain image focu error signal and so on during the wavelength variations of incident light L3 to adjust the position of complex objective lens.
In detail, as shown in Figure 23, raster graphic P4 is designed to that the diffraction light through wave front modifier 56 is generated the transmitted light L4R (or diffraction light L5R) that distinguishes the 56a transmission and changes over a branch of first-order diffraction light L7 and a branch of negative first-order diffraction light L8.Diffraction light L7, L8 are represented by two kinds of spherical waves with different curvature.In other words, by having actual interference at spherical wave with another spherical wave dispersed from focal point S7 of the focal point F P1 of photodetector 57 fronts, produce interference fringe according to the two-beam interference metering process, so that form the raster graphic P4 consistent with interference fringe.In other cases, calculate interference fringe according to the computer-generated hologram method.As a result, it is diffracted and become the conjugation diffracted beam of a branch of first-order diffraction light L7 of picture and a branch of negative utmost point diffraction light L8 and so on to generate the transmitted light L4R (or diffraction light L5R) of district 56a transmission through the diffraction light of wave front modifier 56.First-order diffraction light beam L7 has focal point F P1 at the front surface place of photodetector 57, and negative first-order diffraction light beam L8 has focal point F P2 in photodetector 57 back.
As shown in Figure 24, photodetector 57 comprises a sextant photodetector 59 (or six fens photodetectors), is provided with six detecting area SE1, SE2, SE3, SE4, SE5 and SE6 in detector 59.The intensity of first-order diffraction light L7 is by each detecting area SE1, SE2 of sextant photodetector 59 and SE3 detection and become current signal SC1, SC2 and SC3.Equally, the intensity of negative first-order diffraction light L8 is surveyed by each detecting area SE4, SE5 of sextant photodetector 59 and SE6 and is become current signal SC4, SC5 and SC6.
Figure 25 A and 25C are illustrated respectively in object lens 27 and shine in the focal point of the first-order diffraction light L7 of detecting area SE1, the SE2 of sextant photodetector 59 and SE3 under the condition that defocuses on information medium 23 or 25 and shine in another focal point of the negative first-order diffraction light L8 of detecting area SE4, the SE5 of sextant photodetector 59 and SE6.Figure 25 B is illustrated in object lens 27 and just shines in the focal point of the first-order diffraction light L7 of detecting area SE1, the SE2 of sextant photodetector 59 and SE3 under the condition that focuses on information medium 23 or 25 and shine in another focal point of the negative first-order diffraction light L8 of detecting area SE4, the SE5 of sextant photodetector 59 and SE6.
As shown in Figure 25 A to 25C, under the condition that defocuses on the information medium 23 (or 25), be focused under the situation of information medium 23 (or 25) at object lens 27 at transmitted light L4 (or diffraction light L5), on sextant photodetector 59, form the focal point S8 of the diffraction light L7 shown in the left side of Figure 25 A, 25C, and on sextant photodetector 59, form the focal point S9 of the diffraction light L8 shown in the right side of Figure 25 A, 25C.Different therewith, just under the condition that information medium 23 (or 25) upward focuses on, be focused under the situation of information medium 23 (or 25) at object lens 27 at transmitted light L4 (or diffraction light L5), on six instrument photodetectors 59, form the focal point S8 of the diffraction light L7 shown in the left side of Figure 25 B, and on sextant photodetector 59, form another focal point S9 of the diffraction light L8 shown in the right side of Figure 25 B.The intensity of diffraction light L7 is detected in each detecting area SE1, SE2 of sextant photodetector 59 and SE3 and becomes current signal SC1, SC2, SC3.Equally, the intensity of diffraction light L8 is detected in detecting area SE4, the SE5 of sextant photodetector 59 and SE6 and becomes current signal SC4, SC5 and SC6.After this, obtain focus error signal S according to the spot definition probe method by computing formula (5) Fe
S fe＝(SC1+SC3-SC2)-(SC4+SC6-SC5)(5)
After this, along the position of optical axis direction, so that focus error signal S with the high-speed mobile complex objective lens FeAbsolute value reduce to minimum.
In the spot definition probe method, diffraction light L7, L8 represent so that survey focus error signal S with two kinds of spherical waves with different curvature FeYet, shine in two bundle diffraction light L7, the L8 of photodetector 57 and be not limited to spherical wave.In other words, because diffraction light L7, L8 survey according to the spot definition probe method by photodetector 57 along the variation of Y direction, need the one dimension focus of diffraction light L7 to be positioned at before the photodetector 57 and the one dimension focus of diffraction light L8 is positioned at after the photodetector 57.Thereby the diffraction light that comprises astigmatic aberration can shine on photodetector 57.
In addition, by all current signal additions being obtained information signal Sin according to formula (6).
Sin＝SC1+SC2+SC3+SC4+SC5+SC6(6)
Because information medium 23 or 25 high speed rotating, the graphics track pit of focal point S8, the S9 irradiation of diffracted smooth L7, L8 is Fast transforms one by one, so that the intensity of information signal Sin changes.Thereby, can reappear the information that is stored in information medium 23 or 25 according to information signal Sin.
Next describe according to the relative position between focal point on information medium 23 or 25 and the graphics track pit and come the detecting and tracking error signal.
The raster graphic P5 that is drawn among the diffraction light generation district 56b shown in Figure 22 is designed to the transmitted light L4R (or diffraction light L5R) through the diffraction light generation district 56b of wave front modifier 56 transmission is become a branch of first-order diffraction light L9 and a branch of negative first-order diffraction light L10.Moreover the raster graphic P6 that is drawn among the diffraction light generation district 56c shown in Figure 22 is designed to the transmitted light L4R (or diffraction light L5R) through the diffraction light generation district 56c of wave front modifier 56 transmission is become a branch of first-order diffraction light L11 and a branch of negative first-order diffraction light L12.
As shown in Figure 24, photodetector 57 also comprises four tracking illumination electric explorer 60a to 60d that are used for surveying the intensity of diffraction light L9 to L12.As shown in Figure 26, the tracked photodetector 60a detection of the intensity of diffraction light L9 also becomes current signal SC7, the tracked photodetector 60d detection of the intensity of diffraction light L10 also becomes current signal SC10, the tracked photodetector 60b of the intensity of diffraction light 11 surveys and becomes current signal SC8, and the tracked photodetector 60c of the intensity of diffraction light L12 surveys and become current signal SC9.Calculate tracking error signal S according to formula (7) Te
S te＝SC7-SC8-SC9+SC10(7)
Thereby the asymmetry of intensity distributions that is incident on the transmitted light L4R (or diffraction light L5R) on the wave front modifier 56 is by tracking error signal S TeRepresent that this asymmetry changes according to focal point S1 (or S2) and by the position relation between the graphics track pit of light L4 or L5 irradiation.
After this, radially mobile object lens 27 are to reduce by tracking error signal S TeIndicated tracking error.Radially be defined by not only perpendicular to optical axis but also perpendicular to the direction of a series of graphics track pits.Thereby the focal point S1 (or S2) of transmitted light L4 (or diffraction light L5) on information medium 23 (or 25) can form in the middle of the graphics track pit, so that the tracking error vanishing.
Therefore, in optical head device 51, can stably obtain focusing on and the tracking servo characteristic.In other words, change function, can obtain focus error signal at an easy rate because wave front modifier 56 has wave front.Equally, owing in wave front modifier 56, be provided with diffraction light generating region 56b, 56c, can be easy to obtain tracking error signal.Thereby, make optical head device 51 required part numbers and can reduce, and number of manufacture steps can reduce.In addition, the optical head installation cost of manufacturing is low, in light weight.
Moreover, owing in optical head device 51, use complex objective lens with two focuses, no matter information medium be actually thick be thin, can both be with luminosity head unit 51 from reliable recording on the information medium or reproduction message segment.
(the 7th embodiment)
Next describe optical head device, in this device, survey the servosignal of image focu error signal and tracking error signal and so on according to the astigmatic aberration method according to seventh embodiment of the invention.
Figure 27 is the constitutional diagram according to the optical head device of the 7th embodiment.
As shown in Figure 27, a kind of be used for or from information medium 23 25 the record or the reproduction message segment optical head device 61 comprise light source 52, collimation lens 53, beam splitter 54, by hologram lens 26 (or 26M, 32,33 or 42) and complex objective lens 29 (or the 29M that forms of object lens 27,34,43,45,46 or 47), actuating unit 58, condenser 55, astigmatic aberration generating apparatus 62 that is used in transmitted light L4R that is assembled by condenser 55 or diffraction light L5R, generating astigmatic aberration as parallel plane sheet and so on, and a photodetector 63 that is used for surveying the intensity of transmitted light L4R or diffraction light L5R, generate astigmatic aberration therein to obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.
Astigmatic aberration generating apparatus 62 belongs to one of wave front modifier 56, changes so that generate astigmatic aberration in light L4R or L5R because the wave front of transmitted light L4R or diffraction light L5R is generated device 62.Moreover the normal of device 62 is from inclined light shaft.
As shown in Figure 28, photodetector 63 comprises a sector photodetector 64, is provided with four detecting area SE7, SE8, SE9 and SE10 in detector 64.
In above structure, the transmitted light L4R (or diffraction light L5R) that is reflected by information medium 23 (or 25) by condenser 55 with the 6th embodiment in same way as assemble.After this, transmitted light L4R (or diffraction light L5R) is through 62 transmissions of astigmatic aberration generating apparatus and be focused on the photodetector 63 so that form focal point S10 on detecting area SE7, SE8, SE9 and the SE10 at sector photodetector 64.In this case, because the transmitted light L4R (or diffraction light L5R) that is assembled by condenser 55 is a spherical wave, astigmatic aberration is generated in transmitted light L4R (or diffraction light L5R) by astigmatic aberration generating apparatus 62.Thereby as shown in Figure 29 A to 29C, the shape of focal point S10 changes significantly according to the distance between complex objective lens 29 and the information medium 23 (or 25).
For example, transmitted light L4 (or diffraction light L5) at object lens 27 under situation about being focused under the condition that defocuses on the information medium 23 (or 25) on the information medium 23 (or 25), on sector photodetector 64, form the focal point S10 of the transmitted light L4R (or diffraction light L5R) shown in Figure 29 A, the 29C.Different therewith, just go up under the situation about being focused under the condition that focuses on the information medium 23 (or 25) at object lens 27 at transmitted light L4 (or diffraction light L5), on sector photodetector 64, form the focal point S10 of the transmitted light L4R (or diffraction light L5R) shown in Figure 29 B at information medium 23 (or 25).
The intensity of transmitted light L4R (or diffraction light L5R) is detected in detecting area SE7, SE8, SE9 or the SE10 of sector photodetector 64 and becomes current signal SC11, SC12, S13 and SC14.After this, obtain focus error signal S according to the astigmatic aberration method by computing formula (8) Fe
S fe＝(SC11+SC14)-(SC12+SC13)(8)
After this, along the position of the direction high-speed mobile complex objective lens 29 parallel, so that focus error signal S with optical axis FeAbsolute value reduce to minimum.
Moreover, as shown in Figure 29 D, defined the tangential D consistent with the extending direction of graphic recording pit tNot only vertical with optical axis but also vertical radially Dr with the graphic recording pit.In this case, when sector photodetector 64 is orientated as shown in Figure 29 A to 29C, utilize the intensity distribution variation of transmitted light L4R (or diffraction light L5R) to calculate tracking error signal S according to formula (9) Te, this intensity distribution variation depends on focal point S10 and is concerned by the position between the record pit of light L4 or L5 irradiation.
D te＝SC11+SC13-(SC12+SC14)(9)
After this, radially mobile object lens 27 are to reduce by tracking error signal S TeIndicated tracking error.Thereby the focal point S1 (or S2) of transmitted light L4 (or diffraction light L5) on information medium 23 (or 25) can form in the middle of the record pit, so that the tracking error vanishing.
In other cases, obtain tracking error signal S according to phase difference method with the result of calculation in the formula (9) Te
In addition, by all current signal additions being obtained information signal Sin according to formula (10).
Sin＝SC11+SC12+SC13+SC14(10)
Therefore, in optical head device 61, can stably obtain focusing on and the tracking servo characteristic.In other words, owing in transmitted light L4R (or diffraction light L5R), generate astigmatic aberration, can obtain the servosignal of image focu error signal and tracking error signal and so at an easy rate by the astigmatic aberration generating apparatus of forming by the parallel plane sheet 62.Thereby, make optical head device 61 required part numbers and can reduce, and number of manufacture steps can reduce.In addition, the optical head installation cost of manufacturing is low, in light weight.
Moreover, owing in optical head device 61, use complex objective lens with two focuses, no matter information medium be actually thick be thin, can both be with luminosity head unit 61 from reliable recording on the information medium or reproduction message segment.
In the 7th embodiment, the astigmatic aberration generating apparatus 62 that is formed by the parallel plane sheet is arranged between condenser 55 and the photodetector 63.Yet the optical head device 65 shown in the image pattern 30 is such, the cylindrical lens 66 that forms integral body with condenser 55 can be set replace the parallel plane sheet so that generate astigmatic aberration in transmitted light L4R (or diffraction light L5R).In this case, because cylindrical lens 66 forms integral body with condenser 55, can make the optical head device with lower cost.In addition, as shown in Figure 30, the normal of hologram lens 26 (or 32,33,42) can approximately once incide on photodetector 57 or 63 at the diffused light of the surface reflection of hologram lens 26 preventing from the inclined light shaft that passes object lens 27 centers.Moreover hologram lens 26 (or 32,33,42) can cover to prevent the generation of diffused light with anti-reflection coating.
Moreover the optical head device 67 shown in the image pattern 31 is such, can be provided with that polarization beam apparatus 68 replaces beam splitter 54 so that transmission incident light L3 and add 1/4-λ plain film 69 between hologram lens 26 (or 32,33,42) and polarization beam apparatus 68 fully.In this case, since incident light L3 on the emitting light path through 69 transmissions of 1/4-λ plain film and also since transmitted light L4R (or diffraction light L5R) on input path once more through 69 transmissions of 1/4-λ plain film, reflect fully so transmitted light L4R (or diffraction light L5R) is polarized beam splitter 68.Therefore can improve the utilization factor of incident light L3.Moreover, can improve the signal to noise ratio (S/N ratio) of each servosignal and information signal.
Equally, the optical head device 70 shown in the image pattern 32 is such, can be provided with that polarization beam apparatus 68 replaces beam splitter 54 so that transmission incident light L3 and add 1/4-λ plain film 69 between hologram lens 26 (or 32,33,42) and object lens 27 fully.In this case, transmitted light L4R (or diffraction light L5R) is polarized beam splitter 68 and reflects fully in the mode identical with the device of optical head shown in Figure 31.In addition since from the diffused light of holographic lens 26 (or 32,33,42) reflection through polarization beam apparatus 68 transmissions, diffused light does not incide on the photodetector 63.Therefore, the signal to noise ratio (S/N ratio) of each servosignal and information signal can further improve.
Equally, the optical head device 71 shown in the image pattern 33 is such, can add the prism wedge 72 that is used for to from the incident light L3 shaping of light source 52 emission between collimation lens 53 and polarization beam apparatus 68.In this case, the elliptical wave front of incident light L3 is shaped to circular wavefront by prism wedge 72.Therefore can improve the utilization factor of incident light L3.
In the 6th and the 7th embodiment, when the transmitted light L4 on being focused at first information medium 23 (being zero order diffracted light L4) is recorded in a segment information on the first information medium 23 towards complex objective lens reflection with reproduction, part transmitted light L4R is diffracted in hologram lens 26 (or 32,33,42) on the input path, so that this part transmitted light L4R becomes a branch of first-order diffraction light L13.Thereby first-order diffraction light L13 disperses from hologram lens 26, and forms the focal point S11 of diffraction light L13 with bigger size on photodetector 57 or 63, as shown in Figure 34.The size of focal point S11 is greater than the focal point size of sextant photodetector 59 and sector photodetection suitable 64.Thereby, exist the shortcoming that signal to noise ratio (S/N ratio) degenerates in the information signal.
In order to solve this shortcoming, preferably photodetector 57 (or 63) also comprises an information photodetector 73 around sextant photodetector 59 (or sector photodetector 64).It is square that the size of information photodetector 73 is equal to or greater than 1mm.Thereby, under the situation of information signal depends on the transmitted light L4 that is surveyed in sextant photodetector 59 (or sector photodetector 64) intensity and the intensity sum of the diffraction light L13 that in information photodetector 73, is surveyed, the signal to noise ratio (S/N ratio) in the information signal can be improved, and the frequency characteristic of information signal can be improved.
(the 8th embodiment)
Next, description is carried out method of focusing according to eighth embodiment of the invention in optical head device 51,61,65,67,70 and 71.
Figure 35 A illustrates the variation of the focus error signal that obtains by the intensity of surveying the transmitted light L4 that forms in hologram lens 26,32 or 33, and the intensity of focus error signal depends on the distance between object lens 27 and the first information medium 23.Figure 35 B diagram is by surveying the variation of the focus error signal that the intensity of diffraction light L5 obtains in hologram lens 26,32 or 33, and the intensity of focus error signal depends on the distance between the object lens 27 and second information medium 25.
The intensity of transmitted light L4 is very high, because the numerical aperture of 27 couples of transmitted light L4 of object lens is very big.Thereby, shown in Figure 35 A, the variation of the focus error signal FE1 that obtains under object lens 27 almost focus on situation on the first information medium 23 is compared bigger significantly with the variation of the unnecessary focus error signal FE2 that obtains under situation about defocusing on the first information medium 23 at object lens 27.In addition, be used at hologram lens 26,32 or 33 under the situation of each luminosity device head unit 51,61,65,70 and 71, when the distance between object lens 27 and the first information medium 23 generates unnecessary focus error signal FE2 during greater than the focal length of 27 couples of transmitted light L4 of object lens.
Different therewith, the intensity of diffraction light L5 reduces, because the numerical aperture of 27 couples of diffraction light L5 of object lens is less.Thereby, as shown in Figure 35 B, the variation of the focus error signal FE3 that obtains under object lens 27 almost focus on situation on second information medium 25 and the variation of the unnecessary focus error signal FE4 that obtains under situation about defocusing on second information medium 25 at object lens 27 are much at one.In addition, be used at hologram lens 26,32 or 33 under the situation of each optical head device 51,61,65,67,70 and 71, when the distance between the object lens 27 and second information medium 25 generates unnecessary error signal FE4 during less than the focal length of 27 couples of diffraction light L5 of object lens.
Thereby, realizing that transmitted light L4 under situation about focusing on the first information medium 23, places the object lens 27 away from first information medium 23 to move closer to first information medium 23.After this, when the intensity of focus error signal reaches threshold value, being located at focus servo loop in photodetector 57 or 63 state of devoting oneself to work, so that adjusting object lens 27 and focus on the first information medium 23.Equally, realizing that diffraction light L5 under situation about focusing on second information medium 25, places the object lens 27 away from second information medium 25 to move closer to second information medium 25 with the same manner.After this, when the intensity of focus error signal reaches threshold value, being located at focus servo loop in photodetector 57 or 63 state of devoting oneself to work, so that adjusting object lens 27 and make it to focus on second information medium 25.
Therefore, can prevent the harmful effect of unnecessary focus error signal FE4 to the focusing of diffraction light L5.Moreover, actually no matter or owing to place object lens 27 away from information medium 23 or 25 to move closer to information medium 23 or 25 and information medium thickness T1 T2, so in each has the optical head device 51,61,65,67,70 and 71 of hologram lens 26,32 or 33, can carry out focusing operation according to same program, way is to change threshold value or carry out automatic gain control, in this control by the total intensity of surveying transmitted light L4R or diffraction light L5R focus error signal normalization.Thereby, can carry out the required control circuit of focusing operation with the low cost manufacturing.
Figure 36 A illustrates the variation of the focus error signal that obtains by the intensity of surveying the diffraction light L6 that forms in hologram lens 42, and the intensity of focus error signal depends on the distance between object lens 27 and the first information medium 23.Figure 36 B illustrates the variation of the focus error signal that obtains by the intensity of surveying the transmitted light L4 that forms in holographic lens 42, and the intensity of focus error signal depends on the distance between the object lens 27 and second information medium 25.
As shown in Figure 36 A, the variation of the focus error signal FE5 that obtains under object lens 27 almost focus on situation on the first information medium 23 is compared bigger significantly with the variation of the unnecessary focus error signal FE6 that obtains under situation about defocusing on the first information medium 23 at object lens 27.In addition, be used at hologram lens 42 under the situation of each optical head device 51,61,65,67,70 and 71, when the distance between object lens 27 and the first information medium 23 generates unnecessary focus error signal FE6 during less than the focal length of 27 couples of diffraction light L6 of object lens.
Different therewith, as shown in Figure 36 B, the variation of the focus error signal FE7 that obtains under object lens 27 almost focus on situation on second information medium 25 and the variation of the unnecessary focus error signal FE8 that obtains under situation about defocusing on second information medium 25 at object lens 27 are much at one.In addition, be used at hologram lens 42 under the situation of each optical head device 51,61,65,67,70 and 71, when the distance between the object lens 27 and second information medium 25 generates unnecessary focus error signal FE8 during greater than the focal length of 27 couples of transmitted light L4 of object lens.
Thereby, realizing diffraction light L6 under situation about focusing on the first information medium 23, place object lens 27 to leave first information medium 23 gradually near first information medium 23.After this, when the intensity of focus error signal reaches threshold value, being located at focus servo loop in photodetector 57 or 63 state of devoting oneself to work, so that adjusting object lens 27 and make it to focus on the first information medium 23.Equally, realize that transmitted light L4 focuses under the situation on second information medium 25, place object lens 27 to leave second information medium 25 gradually with the same manner near second information medium 25.After this, when the intensity of focus error signal reaches threshold value, being located at focus servo loop in photodetector 57 or 63 state of devoting oneself to work, so that adjusting object lens 27 and make it to focus on second information medium 25.
Therefore, can prevent the harmful effect that unnecessary focus error signal FE8 focuses on transmitted light L4.Moreover, actually no matter or owing to place near information medium 23 or 25 object lens 27 leave message medium 23 or 25 and information medium thickness T1 T2 gradually, so can carry out focusing operation according to same program in each has the optical head device 51,61,65,67,70 or 71 of hologram lens 42, way is to change threshold value or carry out automatic gain control.Thereby, can carry out the required control circuit of focusing operation with the low cost manufacturing.
(the 9th embodiment)
Contrast Figure 29, the 37 optical head devices of describing according to ninth embodiment of the invention that have complex objective lens 29,34,45,46 or 47 effectively utilize incident light L3 and obtain information signal and servosignal in this device.
Figure 37 is the constitutional diagram according to the optical head device of the 9th embodiment.
As shown in Figure 37, be used for or from information medium 23 25 the record or the reproduction message segment optical head device 81 comprise light source 52, collimation lens 53, beam splitter 54, the complex objective lens of forming by hologram lens 26 (or 32 or 33) and object lens 27 29 (34,45,46 or 47), actuating unit 58, condenser 55, be used for the beam splitter 82 of a branch of diffraction light L5R of transmission or reflects one transmitted light L4R, be used for surveying through the intensity of the diffraction light L5R of beam splitter 82 transmissions to obtain servosignal and to be recorded in the photodetector 63 of the information signal on second information medium 25, picture is used for changing the wave front modifier 56 of hologram and so on of wave front of the transmitted light L4R of beam splitter 82 reflections, and be used for surveying the intensity of transmitted light L4R to obtain servosignal and the photodetector 57 that is recorded in the information signal on the first information medium 23.Beam splitter 82 is made of from the parallel plane sheet that light path tilts its normal, so that generates astigmatic aberration in passing the diffraction light L5R of beam splitter 82.Equally, in parallel plane sheet surface applied overlayer is arranged.
In above structure, transmitted light L4 (or diffraction light L5) by condenser 27 with the 6th embodiment in identical mode assemble.After this, or from first information medium 23 record or reappear under the situation of a segment information, transmitted light L4 is focused on the first information medium 23 to form the first focal point S1.After this, a branch of transmitted light L4R by 23 reflections of first information medium passes same light path in opposite direction.In other words, the major part of transmitted light L4R reflects through the complex objective lens transmission and by beam splitter 54 once more without any diffraction ground.After this, transmitted light L4R is assembled by condenser 55, and a part of transmitted light L4R is reflected by beam splitter 82.After this, the wave front of most of transmitted light L4R is changed by wave front modifier 56, and most of transmitted light L4R is focused on the photodetector 57 to form focal point S8, S9.Thereby, with the 6th embodiment in identical mode obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.Moreover the remainder transmitted light L4R that does not change its wave front is focused on the photodetector 57 to form focal point S7.
Different therewith, or from second information medium, 25 records or reappear under the situation of a segment information, diffraction light L5 is focused on second information medium 25 to form the second focal point S2.After this, a branch of diffraction light L5R by 25 reflections of second information medium passes same light path in opposite direction, and most of diffraction light L5R is without any 26 transmissions of diffraction ground warp hologram lens.Thereby diffraction light L5R passes the input path different with emitting light path.After this, diffraction light L5R is reflected by beam splitter 54 and is assembled by condenser 55.After this, a part of diffraction light L5R is through beam splitter 82 transmissions.In this case, in diffraction light L5R, generate astigmatic aberration.After this, diffraction light L5R is focused on the photodetector 63 forming its shape and the identical focal point S12 of focal point S10 shape shown in Figure 29 A to 29C, and the intensity of diffraction light L5R is detected in photodetector 63.Thereby, with the 7th embodiment in identical mode obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.
In this case, though remainder transmitted light L4R through beam splitter 82 transmissions, remainder transmitted light L4R is not focused at focal point S12 place, because transmitted light L4R passes same light path.Moreover though remainder diffraction light L5R is reflected by beam splitter 82, remainder diffraction light L5R is not focused at focal point S7, S8 or S9, because diffraction light L5R passes the input path different with emitting light path.
In the 9th embodiment, because diffraction light L5R is without any 26 transmissions of diffraction ground warp hologram lens, focal point S12 that forms on photodetector 63 and the launching site of light source 52 in mirror image are irrelevant, and the focal point S7 that forms on photodetector 57 is relevant with the launching site of light source 52 in mirror image.In other words, the focus of the diffraction light L5R that is assembled by condenser 55 is different with the focus of the transmitted light L4R that is assembled by condenser 55.Thereby the photodetector 57 and being used for that need be used for surveying the intensity of transmitted light L4R is surveyed the photodetector 63 of the intensity of diffraction light L5R.
Therefore owing in optical head device 81, use complex objective lens with two focuses, can or from the information medium reliable recording or reproduction message segment, no matter and information medium be actually thick be thin.
The example that optical head device 81 is used for various CDs is now described.
Be used for a kind of like this optical disc apparatus at optical head device 81, in this optical disc apparatus record or reproduction be recorded in the slim high density compact disc 23 message segment and only reproduction be recorded under the situation of the message segment in the thick type CD 25, the hologram lens 26,32 in the complex objective lens 29,34,45,46 or 47 or 33 become a branch of first-order diffraction diffraction of light efficient to a branch of light and are set as and are equal to or less than 30% value.Thereby, in light electric explorer 63, reappear and be recorded under the situation of the segment information on the thick type CD 25, can improve each servosignal that in photodetector 63, obtains and the signal to noise ratio (S/N ratio) of information signal, because be used for obtaining servosignal and information signal through the diffraction light L5R of hologram lens 26,32 or 33 transmissions with high efficiency of transmission.In other words, when reproduction is recorded in a segment information on the thick type CD 25, can improve the utilization factor of incident light L3, so that the output power of incident light L3 can reduce to minimum.Moreover even record one segment information is when needing high strength transmitted light L4 on high density compact disc 23, the intensity that does not increase incident light L3 also can be carried out recording of information reliably, because the efficiency of transmission of 26,32 or 33 couples of incident light L3 of hologram lens is very high.Moreover, in photodetector 57, reappear and be recorded under the situation of the segment information on the high density compact disc 23, can improve the signal to noise ratio (S/N ratio) of each signal that in photodetector 57, obtains, because the efficiency of transmission of hologram lens 26,32 or 33 couples of light L3, L4R is very high.
(the tenth embodiment)
Contrast Figure 38, the 39 optical head devices of describing according to tenth embodiment of the invention that have complex objective lens 29,34,45,46 or 47 in this device, effectively utilize incident light L3 and obtain information signal and servosignal.Coordinate X1 shown in Figure 38,39 is identical with Y1.
Figure 38 is the constitutional diagram according to the optical head device of the tenth embodiment.Figure 39 is the planimetric map that is used for the beam splitter that has reflection hologram of the optical head device shown in Figure 38.
As shown in Figure 38, be used for or from information medium 23 25 the record or the reproduction message segment optical head device 91 comprise light source 52, collimation lens 53, beam splitter 54, the complex objective lens of forming by hologram lens 26 (or 32 or 33) and object lens 27 29 (or 34,35,46 or 47), actuating unit 58, condenser 55, the be used for most of transmitted light L4R of transmission or the reflection that have reflective holographic Figure 93 all are incident on the beam splitter 92 of the diffraction light L5R on holographic Figure 93, be used for surveying through the intensity of the transmitted light L4R of beam splitter 92 transmissions to obtain servosignal and to be recorded in the photodetector 63 of the information signal in the first information medium 23, and be used for surveying the intensity of diffraction light L 5R to obtain servosignal and the photodetector 57 that is recorded in the information signal in second information medium 25.
Beam splitter 92 is made of the parallel plane sheet that favours light path, so that generates astigmatic aberration in passing the transmitted light L4R of beam splitter 92.Moreover as shown in Figure 39, reflective holographic Figure 93 is arranged in the core of beam splitter 92, and transmitance region 92a is arranged in the peripheral part around holographic Figure 93 of beam splitter 92.Be incident on light on the transmitance region 92a without any the transmission of diffraction ground.Holographic Figure 93 is divided into the diffraction light that wherein is decorated with raster graphic P7 and generates district 93a and a pair of diffraction light generation district 93b, the 93c that wherein is decorated with a pair of raster graphic P8, P9.The diffraction light L5R that is incident on the diffraction light generation district 93a is diffracted so that obtain focus error signal in photodetector 57.The diffraction light L5R that is incident on each diffraction light generation district 93b, 93c is diffracted so that obtain tracking error signal in photodetector 57.
In above structure, transmitted light L4 and diffraction light L5 by condenser 27 with the 6th embodiment in identical mode assemble.After this, or from first information medium 23 record or reappear under the situation of a segment information, transmitted light L4 is focused on the first information medium 23 to form the first focal point S1.After this, a branch of transmitted light L4R by 23 reflections of first information medium passes same light path in opposite direction.In other words, most of transmitted light L4R reflects through complex objective lens 29 transmissions and by beam splitter 54 once more without any diffraction ground.After this, transmitted light L4R is assembled by condenser 55, and most of transmitted light L4R is through beam splitter 92 transmissions.In this case, in transmitted light L4R, generate astigmatic aberration.After this, transmitted light L4R is focused on the photodetector 63 forming the shape focal point S13 identical with the focal point S10 shown in Figure 29 A to 29C, and the intensity of transmitted light L4R is detected in photodetector 63.Thereby, with the 7th embodiment in identical mode obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.
Different therewith, or from second information medium, 25 records or reappear under the situation of a segment information, diffraction light L5 is focused on second information medium 25 to form the second focal point S2.After this, a branch of diffraction light L5R by 25 reflections of second information medium passes same light path in opposite direction, and most of diffraction light L5R is without any 26 transmissions of diffraction ground warp hologram lens.Thereby, diffraction light L5R with the 9th embodiment in identical mode transmission on the input path different with emitting light path.After this, diffraction light L5R is reflected by beam splitter 54 and is focused on the beam splitter 92 so that form focal point on reflective holographic Figure 93 of beam splitter 92 by condenser 55.Thereby, all diffraction light L5R by holographic Figure 93 diffraction and reflection to be focused on the photodetector 57.In other words, the diffraction light L5R that the diffraction light of holographic Figure 93 generates institute's diffraction among the district 93a and reflection be divided into two bundles and with the 6th embodiment in same way as be focused on the detecting area SE1 to SE6 of the sextant photodetector 59 in the photodetector 57.Moreover the diffraction light L5R of institute's diffraction and reflection is divided into two bundles in the diffraction light generation district 93b of holographic Figure 93, and the intensity of diffraction light L5R is detected in tracking illumination electric explorer 60a and 60d.Moreover the diffraction light L5R of institute's diffraction and reflection is divided into two bundles in the diffraction light generation district 93c of holographic Figure 93, and the intensity of diffraction light L5R is detected in tracking illumination electric explorer 60b and 60c.Thereby, with the 6th embodiment in identical mode obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.
In the tenth embodiment, because transmitted light L4R is without any 26 transmissions of diffraction ground warp hologram lens, the focal point S13 that forms on photodetector 63 has nothing to do with the launching site of light source 52 in mirror image.Thereby the photodetector 57 and being used for that need be used for surveying the intensity of diffraction light L5R is surveyed the photodetector 63 of the intensity of transmitted light L4R.
Therefore owing in optical head device 91, use complex objective lens with two focuses, can or from the information medium reliable recording or reproduction message segment, and no matter information medium be actually thick be thin.
Moreover, because all diffraction light L5R can be utilized diffraction light L5R efficiently by the complete diffraction of holographic Figure 93 and the reflection of beam splitter 92.Thereby, can improve the signal to noise ratio (S/N ratio) of the signal that in photodetector 57, obtains.
The example that optical head device 91 is used for various CDs is described now.
Be used for a kind of like this optical disc apparatus at optical head device 91, in this optical disc apparatus record or reproduction be recorded in the slim high density compact disc 23 message segment and only reproduction be recorded under the situation of the message segment in the thick type CD 25, the hologram lens 26,32 in the complex objective lens 29,34,45,46 or 47 or 33 become a branch of first-order diffraction diffraction of light efficient to a branch of light and are set as and are equal to or less than 30% value.Thereby, in photodetector 57, reappear and be recorded under the situation of the segment information on the thick type CD 25, can improve each servosignal that in photodetector 57, obtains and the signal to noise ratio (S/N ratio) of information signal, because be used for obtaining servosignal and information signal through the diffraction light L5R of hologram lens 26,32 or 33 transmissions with high efficiency of transmission.In other words, when reproduction is recorded in a segment information on the thick type CD 25, can improve the utilization factor of incident light L3, so that the output power of incident light L3 can reduce to minimum.Moreover even record one segment information is when needing high strength transmitted light L4R on high density compact disc 23, the intensity that does not increase incident light L3 also can realize recording of information reliably, because the efficiency of transmission of 26,32 or 33 couples of incident light L3 of hologram lens is very high.Moreover, in photodetector 63, reappear and be recorded under the situation of the segment information on the high density compact disc 23, can improve the signal to noise ratio (S/N ratio) of each signal that in photodetector 63, obtains, because the efficiency of transmission of hologram lens 26,32 or 33 couples of light L3, L4R is very high.
(the 11 embodiment)
Contrast Figure 40 to 42 describes the optical head device that has complex objective lens 29,34,45,46 or 47 according to eleventh embodiment of the invention, effectively utilizes incident light and obtain information signal and servosignal in this device.Coordinate X1 shown in Figure 40,41 is identical with Y1, and coordinate X, the Y shown in Figure 40,42 is identical with Z.
Figure 40 A, 40B are respectively the constitutional diagrams according to the optical head device of the 11 embodiment.Figure 41 is the planimetric map that is used for the beam splitter that has reflection hologram of the optical head device shown in Figure 40.
As Figure 40 A, shown in the 40B, be used for or from information medium 23 and 25 the record or the reproduction message segment optical head device 101 comprise light source 52, collimation lens 53, beam splitter 54, the complex objective lens of forming by hologram lens 26 (or 32 or 33) and object lens 27 29 (or 34,45,46 or 47), actuating unit 58, condenser 55, what have transmission-type hologram 103 is used for that transmission is focused at the transmitted light L4R on the first information medium 23 and the diffraction light L5R and the diffraction that are focused on second information medium 25 defocus the beam splitter 102 that is focused at the transmitted light L4R on second information medium 25, the intensity that is used for surveying the transmitted light L4R that is focused on the first information medium 23 is to obtain servosignal and the information signal that is recorded in the first information medium 23, the intensity that defocuses detection diffraction light L5R is to obtain being recorded in the information signal in second information medium 25, and detection defocuses the photodetector 104 of intensity to obtain focus error signal that is focused at the transmitted light L4R on second information medium 25.
Beam splitter 102 is made of the parallel plane sheet that favours light path, so that generates astigmatic aberration in passing light L4R, the L5R of beam splitter 102.Moreover as shown in Figure 41, transmission-type hologram 103 is arranged in the core of beam splitter 102, and transmitance region 102a is arranged in the peripheral part around holographic Figure 103 of beam splitter 102.Be incident on transmitted light L4R on the transmitance region 102a without any the transmission of diffraction ground, holographic Figure 103 is divided into the diffraction light of alternately arranging and generates district 103a, 103b so that survey focus error signal according to the spot definition probe method described in the 6th embodiment.In other words, in each diffraction light generation district 103a, draw raster graphic P10, and form a focal point by the transmitted light L4R of diffraction in district 103a.Equally, generate the raster graphic P11 that draws among the district 103b, and form another focal point by the transmitted light L4R of diffraction in district 103b at each diffraction light.
Photodetector 104 comprises sextant photodetector 59, in the mode identical with photodetector 57 detecting area SE1, SE2, SE3, SE4, SE5 and SE6 is set in detector 59.
In above structure, transmitted light L4 and diffraction light L5 by condenser 27 with the 6th embodiment in identical mode assemble.After this, or from first information medium 23 record or reappear under the situation of a segment information, as shown in Figure 40 A, transmitted light L4 is focused on the first information medium 23 to form the first focal point S1.After this, a branch of transmitted light L4R by 23 reflections of first information medium passes same light path in opposite direction.In other words, transmitted light L4R reflects through the complex objective lens transmission and by beam splitter 54 once more without any diffraction ground.After this, transmitted light L4R is assembled by condenser 55, and most of transmitted light L4R is through beam splitter 102 transmissions.In this case, in transmitted light L4R, generate astigmatic aberration.After this, transmitted light L4R is focused on the photodetector 104 forming the shape focal point S14 identical with the focal point S10 shown in Figure 29 A to 29C, and the intensity of transmitted light L4R is detected in photodetector 104.Thereby, with the 7th embodiment in identical mode obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.In this case, because the position of the photodetector 104 of detection transmitted light L4R is relevant with the launching site of light source 52 in mirror image, transmitted light L4R just focuses on and is focused on the photodetector 104.
Different therewith, or from second information medium, 25 records or reappear under the situation of a segment information, as shown in Figure 40 B, diffraction light L5 is focused on second information medium 25 to form the second focal point S2.After this, a branch of diffraction light L5R by the reflection of second information medium 25 passes same light path and in opposite direction without any 26 transmissions of diffraction ground warp hologram lens.Thereby, diffraction light L5R with the 9th embodiment in identical mode transmission on the input path different with emitting light path.After this, diffraction light L5R is reflected by beam splitter 54 and is assembled by condenser 55.After this, most of diffraction light L5R is through beam splitter 102 transmissions, and diffraction light L5R is focused on the photodetector 57.In the case, in diffraction light L5R, generate the aberration that looses.Moreover, since diffraction light L5R on the incident road not by hologram lens 26 diffraction, the position of surveying the photodetector 104 of diffraction light L5R has nothing to do with the launching site of light source 52 in mirror image.Thereby diffraction light L5R defocuses and is focused on the photodetector 104.Yet, because the total intensity that defocuses the diffraction light L5R of convergence is detected in photo-detector 104, thus with the 7th embodiment in identical mode obtain information signal.
Moreover transmitted light L4 defocuses and is focused on second information medium 25, as shown in Figure 40 B.In other words, be incident on the front surface place that transmitted light L4 on the rear surface of second information medium 25 converges at second information medium 25.After this, the transmitted light L4R of a branch of front surface reflection at second information medium 25 reflects through the complex objective lens transmission and by beam splitter 54 once more without any diffraction ground.After this, transmitted light L4R is focused on the beam splitter 102 so that form focal point on holographic Figure 103 of beam splitter 102 by condenser 55.Thereby all transmitted light L4R are by holographic Figure 103 diffraction and be focused on the photodetector 104.In other words, the transmitted light L4R of diffraction becomes the first spherical wave SW1 that its focus is positioned at photodetector 104 fronts in the diffraction light generation district 103a of holographic Figure 103, and the transmitted light L4R of diffraction becomes the second spherical wave SW2 that its focus is positioned at photodetector 104 back in the diffraction light generation district 103b of holographic Figure 103.After this, as shown in Figure 42 A to 42C, the detecting area SE1 to SE3 that the first spherical wave SW1 is focused at sextant photodetector 59 in the photodetector 104 goes up with formation focal point S15A, and the second spherical wave SW2 is focused at the detecting area SE4 to SE6 of sextant photodetector 59 upward to form focal point S15B.Because district 103a, 103b are divided into many, focal point S15A, S15B also are divided into many respectively.
Defocus under the situation about being focused on the information medium 25 at diffraction light L5, on sextant photodetector 59, form focal point S15A, the S15B of the transmitted light L4R shown in Figure 42 A, the 42C.Different therewith, focus under the situation about being focused on the information medium 25 at diffraction light L5, on sextant photodetector 59, form focal point S15A, the S15B of the transmitted light L4R shown in Figure 42 B.The intensity of transmitted light L4R is detected in each detecting area SE1 to SE6 of sextant photodetector 59 and becomes current signal SC15 to SC20.After this, obtain focus error signal S according to the spot definition probe method by computing formula (11) Fe
S fe＝(SC15+SC17-SC16)-(SC18+SC20-SC19)(11)
After this, along the position of optical axis direction high-speed mobile complex objective lens, so that focus error signal S FeAbsolute value reduce to minimum.Thereby, with the 6th embodiment in same way as obtain focus error signal.
Therefore owing in optical head device 101, use complex objective lens with two focuses, can or from the information medium reliable recording or reproduction message segment, no matter information medium be actually thick be thin.
Moreover, since whole transmitted light L4R of being reflected of second information medium 25 fully by the complete diffraction of holographic Figure 103 of beam splitter 102 so that survey focus error signal, transmitted light L4R can efficiently utilize.Thereby, can improve the signal to noise ratio (S/N ratio) of the focus error signal that in photodetector 104, obtains.
Moreover, can in photodetector 104, obtain information signal and servosignal, and no matter information medium 23 or 25 is Bao Shihou actually.Thereby, making optical head device 101 required part numbers can reduce, even and information medium be actually thick be thin all with luminosity head unit 101 or from information medium record or reproduction message segment, also can make undersized optical head device with low-cost and light weight.
The example that optical head device 101 is used for various CDs is described.
Be used for a kind of like this optical disc apparatus at optical head device 101, record or reproduction are recorded in the message segment in the slim high density compact disc 23 and only reappear and be recorded under the situation of the message segment in the thick type CD 25 in this optical disc apparatus, and hologram lens 26,32 in the complex objective lens 29,34,45,46 or 47 or 33 diffraction efficiency are set as and are equal to or less than 30% value.Thereby, be recorded under the situation of the segment information on the thick type CD 25 in photodetector 104, reappearing, can improve each servosignal that in photodetector 104, obtains and the signal to noise ratio (S/N ratio) of information signal, because be used for obtaining information signal through the diffraction light L5R of hologram lens 26,32 or 33 transmissions with high efficiency of transmission.In other words, when reproduction is recorded in a segment information on the thick type CD 25, can improve the utilization factor of incident light L3, so that the output power of incident light L3 can reduce to minimum.Moreover even record one segment information is when needing high strength transmitted light L4 on high density compact disc 23, the intensity that does not increase incident light L3 also can realize recording of information reliably, because the efficiency of transmission of 26,32 or 33 couples of incident light L3 of hologram lens is very high.Moreover, be recorded under the situation of the segment information on the high density compact disc 23 in photodetector 63, reappearing, can improve the signal to noise ratio (S/N ratio) of each signal that in photodetector 63, obtains, because the transmission of hologram lens 26,32 or 33 couples of light L3, L4R effect efficient is very high.
(the 12 embodiment)
Contrast Figure 43 describe according to twelveth embodiment of the invention have complex objective lens 29M, 43,45, an optical head device of 46 or 47, in this device, effectively utilize incident light L3 and obtain information signal and servosignal.
Figure 43 is the constitutional diagram according to the optical head device of the 12 embodiment.
As shown in Figure 43, be used for or the complex objective lens 29M (or 43,45,46 or 47), actuating unit 58, condenser 55, beam splitter 82, photodetector 63, wave front modifier 56 and the photodetector 57 that comprise light source 52, collimation lens 53, beam splitter 54, form by hologram lens 42 (or 26M or 32) and object lens 27 from the optical head device 111 of information medium 23 or 25 records or reproduction message segment.
In above structure, in collimation lens 53, collimate and through beam splitter 54 transmissions by a branch of incident light L3 of light source 52 emission.After this, a part of incident light L3 is without any 29 transmissions of diffraction ground warp complex objective lens, and remainder incident light L3 is diffracted.
After this, or from first information medium 23 record or reappear under the situation of a segment information, diffraction light L6 is focused on the first information medium 23 to form focal point S5.In other words, diffraction light L6 is incident on the rear surface of first information medium 23, and forms focal point S5 on the front surface of first information medium 23.After this, a branch of diffraction light L6R in the reflection of the front surface place of first information medium 23 passes same light path in opposite direction, and most of diffraction light L6R is once more by hologram lens 42 diffraction.Thereby, diffraction light L6R transmission on the input path consistent with emitting light path.After this, diffraction light L6R is reflected by beam splitter 54 and is assembled by condenser 55.After this, a part of diffraction light L6R is through beam splitter 82 transmissions.In this case, in diffraction light L6R, generate astigmatic aberration.After this, diffraction light L6R is focused on the photodetector 63 to form the focal point S10 of shape as shown in Figure 29 A to 29C.And the intensity of diffraction light L6R is detected in photodetector 63.Thereby, with the 7th embodiment in identical mode obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.
Different therewith, or from second information medium, 25 records or reappear under the situation of a segment information, transmitted light L4 is focused on second information medium 25 to form focal point S6.In other words, transmitted light L4 is incident on the rear surface of second information medium 25, and forms focal point S6 on the front surface of second information medium 25.After this, a branch of transmitted light L4R in the reflection of the front surface place of second information medium 25 passes same light path in opposite direction.In other words, transmitted light L4R is aimed at by object lens 27 on input path.After this, most of transmitted light L4R is by hologram lens 42 diffraction.Thereby, transmitted light L4R transmission on the input path different with emitting light path.After this, transmitted light L4R is reflected by beam splitter 54 and is assembled by condenser 55.After this, a part of transmitted light L4R is reflected by beam splitter 82.After this, the wave front of most of transmitted light L4R is changed by wave front modifier 56, and most of transmitted light L4R is focused on the photodetector 57 to form focal point S16, S17.Thereby, with the 6th embodiment in identical mode obtain the servo-information of information signal and image focu error signal and tracking error signal and so on.Moreover the remainder transmitted light L4R that is changed its wave front by wave front modifier 56 is not focused on the photodetector 57 to form focal point S18.
In the 12 embodiment, since transmitted light L4R on input path by hologram lens 42 diffraction, focal point S18 that forms on photodetector 57 and the launching site of light source 52 in mirror image are irrelevant, and the focal point S10 that forms on photodetector 63 is relevant with the launching site of light source 52 in mirror image.In other words, the focus of the transmitted light L4R that is assembled by condenser 55 is different with the focus of the diffraction light L6R that is assembled by condenser 55.Thereby the photodetector 57 and being used for that need be used for surveying the intensity of transmitted light L4R is surveyed the photodetector 63 of the intensity of diffraction light L6R.
Therefore, though or from information medium record or reproduction message segment, also can or from the information medium reliable recording or reproduction information, and no matter information medium be actually thick be thin.
Moreover because the diffraction light L6 that forms in hologram lens 42 assembled before diffraction light L6 is incident on the object lens 27, the distance along optical axis direction between focal point S5, the S6 can be lengthened to about 1mm.Thereby, be focused at focal point S6 (or S5) upward so that write down or read a segment information even transmitted light L4 (or diffraction light L6) focuses on, light L6 (or L4) also out-focus is focused at focal point S6 (or S5) upward so that reduce the intensity that light L6 (or L4) locates at focal point S6 (or S5).Therefore, recording of information or reproduction there is not harmful effect.
Moreover, because 42 pairs of first-order diffraction light of hologram lens L6 blistering lensing can prevent the appearance of chromatic aberration in optical head device 111.
The example that optical head device 111 is used for various CDs is described now.
Be used for a kind of like this optical disc apparatus at luminosity device 111, in this optical disc apparatus record or reproduction be recorded on the slim high density compact disc 23 message segment and only reproduction be recorded under the situation of the message segment on the thick type CD 25, the hologram lens 26M among the complex objective lens 29M, 43,45,46 or 47 or 42 becomes a branch of first-order diffraction diffraction of light efficient to a branch of light and is set as and is equal to or greater than 55% value.Thereby, be recorded under the situation of the segment information on the thick type CD 25 in photodetector 57, reappearing, can improve each servosignal that in photodetector 57, obtains and the signal to noise ratio (S/N ratio) of information signal, because be used for obtaining servosignal and information signal by the transmitted light L4R of hologram lens 26M or 42 diffraction with high-diffraction efficiency.In other words, when reproduction is recorded in a segment information on the thick type CD 25, can improve the utilization factor of incident light L3, so that the output power of incident light L3 can reduce to minimum.Moreover, even record one segment information needs high strength diffraction light L6 on high density compact disc 23, the intensity that does not increase incident light L3 also can realize recording of information reliably, because the diffraction efficiency of the hologram lens 26M or the 42 couples of incident light L3 and diffraction light L6R is very high.Moreover, be recorded under the situation of the segment information on the high density compact disc 23 in photodetector 63, reappearing, can improve the signal to noise ratio (S/N ratio) of each signal that in photodetector 63, obtains, because the diffraction efficiency of hologram lens 26M or 42 couples of light L3, L6R is very high.
(the 13 embodiment)
Contrast Figure 44 describe according to thriteenth embodiment of the invention have complex objective lens 29M, 43,45, an optical head device of 46 or 47, in this device, effectively utilize incident light L3 and obtain information signal and servosignal.
Figure 44 is the constitutional diagram according to the optical head device of the 13 embodiment.
As shown in Figure 44, be used for or the complex objective lens 43M (or 29M, 45,46 or 47), actuating unit 58, condenser 55, the beam splitter 92 that has reflective holographic Figure 93, photo-detector 63 and the photodetector 57 that comprise light source 52, collimation lens 53, beam splitter 54, form by hologram lens 42 (or 26M or 32) and object lens 27 from the optical head device 121 of information medium 23 or 25 records or reproduction message segment.
In above structure, transmitted light L4 and diffraction light L6 by condenser 27 with the 12 embodiment in identical mode assemble.After this, or from first information medium 23 record or reappear under the situation of a segment information, diffraction light L6 is focused on the first information medium 23 to form focal point S5.After this, a branch of diffraction light L6R by 23 reflections of first information medium passes same light path in opposite direction, and most of diffraction light L6R is by hologram lens 42 diffraction.Thereby, diffraction light L6R with the input path of emitting light path unanimity on with the 12 embodiment in identical mode transmission.After this, diffraction light L6R is reflected by beam splitter 54 and is focused on the beam splitter 92 so that form focal point on reflective holographic Figure 93 of beam splitter 92 by condenser 55.Thereby, all diffraction light L6R by holographic Figure 93 diffraction with reflection in case with the tenth embodiment in identical mode be focused on the photodetector 57.Thereby, with the 6th embodiment in identical mode obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.
Different therewith, or from second information medium, 25 records or reappear under the situation of a segment information, transmitted light L4 is focused on second information medium 25 to form focal point S6.After this, a branch of transmitted light L4R by 25 reflections of second information medium passes same light path in opposite direction.In other words, most of transmitted light L4R is aimed at by object lens 27 on input path.After this, most of transmitted light L4R is by hologram lens 42 diffraction.Thereby, transmitted light L4R on the input path different with emitting light path with the 12 embodiment in identical mode transmission.After this, transmitted light L4R is reflected by beam splitter 54 and is assembled by condenser 55.After this, most of transmitted light L4R is through beam splitter 92 transmissions.In this case, in transmitted light L4R, generate astigmatic aberration.After this, transmitted light L4R is focused on the photodetector 63 forming the shape focal point S19 identical with the focal point S10 shown in Figure 29 A to 29C, and the intensity of transmitted light L4R is detected in photodetector 63.Thereby, with the 7th embodiment in identical mode obtain the servosignal of information signal and image focu error signal and tracking error signal and so on.
In the 13 embodiment, because transmitted light L4R is by hologram lens 42 diffraction, focal point S19 that forms on photodetector 63 and the launching site of light source 52 in mirror image are irrelevant, thereby the photodetector 57 and being used for that need be used for surveying the intensity of diffraction light L6R is surveyed the photodetector 63 of the intensity of transmitted light L4R.
Therefore owing in optical head device 121, use complex objective lens with two focuses, can or from the information medium reliable recording or reproduction message segment, and no matter imformosome be actually thick be thin.
Moreover because the diffraction light L6 that forms in hologram lens 42 assembled before diffraction light L6 is incident on the object lens 27, the distance along optical axis direction between focal point S5, the S6 can be lengthened to about 1mm.Thereby, be focused at that focal point S6 (or S5) goes up so that record or when reading a segment information even transmitted light L4 (or diffraction light L6) focuses on, light L6 (or L4) also out-focus is focused at focal point S6 (or S5) and goes up so that reduce the intensity that light L6 (or L4) locates at focal point S6 (or S5).Therefore, recording of information or reproduction there is not harmful effect.
Moreover, because 42 pairs of first-order diffraction light of hologram lens L6 blistering lensing can prevent the appearance of chromatic aberration in optical head device 121.
The example that optical head device 121 is used for various CDs is described now.
Be used for a kind of like this optical disc apparatus at optical head device 121, in this optical disc apparatus record or reproduction be recorded on the slim high density compact disc 23 message segment and only reproduction be recorded under the situation of the message segment on the thick type CD 25, the hologram lens 26M among the complex objective lens 29M, 43,45,46 or 47 or 42 becomes a branch of first-order diffraction diffraction of light efficient to a branch of light and is set as and is equal to or greater than 70% value.Thereby, be recorded under the situation of the segment information on the thick type CD 25 when in photodetector 57, reappearing, can improve each servosignal that in photodetector 57, obtains and the signal to noise ratio (S/N ratio) of information signal, because be used for obtaining servosignal and information signal by the transmitted light L4R of hologram lens 26M or 42 diffraction with high-diffraction efficiency.In other words, when reproduction is recorded in a segment information on the thick type CD 25, can improve the utilization factor of incident light L3, so that the output power of incident light L3 can reduce to minimum.Moreover, even when record one segment information needs high strength diffraction light L6 on high density compact disc 23, the intensity that does not increase incident light L3 also can be carried out recording of information reliably, because the diffraction efficiency of the hologram lens 26M or the 42 couples of incident light L3 and diffraction light L6R is very high.Moreover, be recorded under the situation of the segment information on the high density compact disc 23 when in light electric explorer 63, reappearing, can improve the signal to noise ratio (S/N ratio) of each signal that in photodetector 63, obtains, because the diffraction efficiency of hologram lens 26M or 42 couples of light L3, L6R is very high.
(the 14 embodiment)
Contrast Figure 44, the 46 optical head devices of describing according to fourteenth embodiment of the invention reduce the noise that is included in the information signal in this device.
Figure 45 is the constitutional diagram according to the optical head device of the 14 embodiment.Figure 46 is the planimetric map that is used for the hologram lens of the optical head device shown in Figure 45.
As shown in Figure 45, be used for or from information medium 23 25 the record or the reproduction message segment optical head device 131 comprise light source 52, one have in its surface polarization color separation film 133 be used for reflection on the emitting light path from the incident light L3 of light source 52 emission and on input path transmission at information medium 23 or the light L4R of 25 reflections or the beam splitter 132 of L5R, one is used for aiming at incident light L3 on the emitting light path and the collimation lens 134 of converging light L4R or L5R on input path, hologram lens 135 that are used for without any diffraction ground transmission part incident light L3 and diffraction remainder incident light L3,1/4-λ sheet 69, object lens 27, actuating unit 58, and be used for surveying on input path through 135 transmissions of hologram lens or by the photodetector 136 of the light of its diffraction.
As shown in Figure 46, form hologram lens 135 by in the 135a of the center of transparent substrate 28, draw the raster graphic P1 and the raster graphic P12 that in periphery district 135b, draws around center 135a.Raster graphic P12 is drawn as non-concentric shape.The raster graphic P1 owing to draw in hologram lens 135 is made of the complex objective lens 137 with two focuses hologram lens 135 and object lens 27.The light that passes the periphery district 135b of hologram lens 135 is surveyed with elimination by photodetector 136 and is included in noise in the information signal.The optical axis of optical head device 131 passes the central point of raster graphic P1 and the central shaft of object lens 27.
Photodetector 136 comprises the sector photodetector 64 that has detecting area SE7 to SE10 and is used for surveying the noise removing photodetector 138 of the light intensity of the periphery district 135b that passes hologram lens 135.Because the raster graphic P12 of periphery district 135b is drawn as non-concentric shape, the light of diffraction is not focused on the detecting area SE7 to SE10 in periphery district 135b.
In above structure, 52 emissions and reflected by beam splitter 132 along the incident light L3 of first direction linear polarization from light source are because 133 couples of incident light L3 along the first direction linear polarization of polarization color separation film play the mirror effect.Thereby incident light L3 is introduced to direction and collimated lens 134 alignings up.After this, a part be incident on incident light L3 on the center 135a of hologram lens 135 without any the 135a transmission of diffraction ground warp center forming transmitted light L4, and the incident light L3 that remainder is incident on the center 135a of hologram lens 135 is diffracted to form diffraction light L5 in the 135a of center.Moreover, a part be incident on incident light L3 on the periphery district 135b of hologram lens 135 without any diffraction ground warp periphery district 135b transmission to form a branch of periphery light L14.After this, light L4, L5 and L14 pass 1/4-λ sheet so that become circularly polarized smooth L4, L5 and L14 along light L4, L5 and the L14 of first direction linear polarization.After this, light L4, L5 and L14 are assembled by condenser 27.
After this, when or write down or reappear under the situation of a segment information from first information medium 23 (or second information medium 25), transmitted light L4 (or diffraction light L5) is focused at information medium 23 (or 25) and goes up to form focal point S1 (or S2).After this, passed a light path in opposite direction by a branch of transmitted light L4R (or a branch of diffraction light L5R) of information medium 23 (or 25) reflection.In other words, transmitted light L4R (or diffraction light L5R) opposite circular polarization also passes condenser 27 and 1/4-λ sheet 69 once more.Thereby light L4R (or L5R) is along the second direction linear polarization vertical with first direction.After this, a part of transmitted light L4R is without any the center 135a transmission of diffraction ground warp hologram lens 135, and perhaps a part of diffraction light L5R is diffracted once more in the 135a of center.After this, the collimated lens 134 of transmitted light L4R (or diffraction light L5R) are assembled and are not passed beam splitter 132 with having any diffraction, because 133 couples of light L4R (or L5R) along the second direction linear polarization of polarization color separation film play the slide effect.In this case, with the 7th embodiment in identical mode in transmitted light L4R (or diffraction light L5R), generate astigmatic aberration.After this, transmitted light L4R (or diffraction light L5R) is incident on the detecting area SE7 to SE10 of photo-detector 136 upward to form its shape focal point S20 identical with the focal point S10 shown in Figure 29 A to 29C.The intensity of transmitted light L4R (or diffraction light L5R) becomes current signal SC21 to SC24 in detector SE7 to SE10.Thereby, with with the 7th embodiment in identical mode obtain the servosignal of image focu error signal and tracking error signal and so on so that adjust the position of compound lens 137 so that transmitted light L4 (or diffraction light L5) focusing is focused on the information medium 23 (or 25).Moreover, obtain the information signal that representative is recorded in the segment information on the information medium 23 (or 25) according to formula (12).
Sin＝SC21+SC22+SC23+SC24(12)
Moreover periphery light L14 is focused on the information medium 23 to form the focal point around focal point S1.After this, a branch of periphery light L14R by 23 reflections of first information medium passes same light path in opposite direction.In other words, noise removing light L14R passes condenser 27 and 1/4-λ sheet 69 once more, and a part of periphery light L14R diffraction and convergence in the periphery district of hologram lens 135 135b, forming a branch of noise removing light L14R, and this noise removing light L14R is incident on the noise removing photodetector 138.In photodetector 138, according to the intensity generation output signal SC25 of noise removing light L14R.After this, by according to formula (13) all signal plus being obtained representing the information signal Snc of the noise removing that is recorded in the segment information on the first information medium 23:
Snc＝(SC21+SC22+SC23+SC24)+R×SC25(13)
Symbol R is a weight factor in the formula.
In this case, owing to add R * SC25 item to obtain information signal Snc, the noise that is included in (SC21+SC22+SC23+SC24) can reduce the harmful effect of the information signal Snc of noise removing.Its reason is described.
As known (for example, the not unexamined patent application that belongs to interim announcement 1985 No. 138748 and announce of Japanese patent gazette nineteen ninety No. 22452 public examination on the 23rd July in 1985 1986 No. 131245) like that, the signal that representative is recorded in the message segment on the CD uprises along with the density of institute's recorded information and shifts to higher frequency.Moreover, producing under the situation of signal by the light that passes hologram lens center district, compare with amplitude with low-frequency signal, have the amplitude step-down of high-frequency signal.Different therewith, producing under the situation of signal by the light that passes hologram lens periphery district, the amplitude with high-frequency signal is reinforced.Thereby, obtaining under the situation of information signal Snc according to formula (13), the high fdrequency component that is included among the information signal Snc is reinforced, and the low-frequency noise component that is included in (SC21+SC22+SC23+SC24) item reduces relatively.As a result, can improve the signal to noise ratio (S/N ratio) of information signal Snc.
Therefore owing in optical head device 131, use complex objective lens with two focuses, can or from the information medium reliable recording or reproduction message segment, and no matter information medium be actually thick be thin.
Moreover, even message segment is recorded on the slim high density compact disc by first information medium 23 representatives thick and fast, also can reappear information signal Snc reliably with very high signal to noise ratio (S/N ratio).
Moreover owing to be incident on light L4R on the detecting area SE7 to SE10 of photodetector 136 or the intensity of L5R is lowered by noise removing light L14R is focused on the photodetector 138, the bearing accuracy of photodetector 136 can approximately be reduced to 1/100.
Moreover, at the raster graphic P12 of periphery district 135b the incident light L3 of diffraction in periphery district 135b is risen under the situation of lensing, on first information medium 23, form the bigger focal point that defocuses at the unnecessary diffraction light that in periphery district 135b, generates on the emitting light path.Thereby the message segment that is recorded on the first information medium 23 is read by unnecessary diffraction light, even and unnecessary diffraction light be incident on the photodetector 136, this information is also handled as one section average information in photodetector 136.Therefore, the information of being read by unnecessary diffraction light does not have harmful effect as noise to information signal Snc.
Moreover, under the efficiency of transmission of the periphery district of the hologram lens 135 135b situation consistent, compare the secondary maximum (or side wave lobe) that occurs around focal point S1 with first embodiment and can reduce with another efficiency of transmission of center 135a.Therefore, can improve the signal to noise ratio (S/N ratio) of information signal Snc.
(the 15 embodiment)
Contrast Figure 47 to 49 describes the optical head device according to fifteenth embodiment of the invention, reduces the noise that is included in the information signal in this device.
Figure 47 is the constitutional diagram according to the optical head device of the 15 embodiment.Figure 48 is the planimetric map that is used for the hologram lens of the optical head device shown in Figure 45.
As shown in Figure 47, be used for or from information medium 23 25 the record or the reproduction message segment optical head device 141 comprise light source 52, beam splitter 82, collimation lens 134, hologram lens 142 that are used for without any diffraction ground transmission part incident light L3 and diffraction remainder incident light L3, object lens 27, operating means 58, and be used for surveying on input path through 142 transmissions of hologram lens or by the photodetector 143 of the light of its diffraction.
As shown in Figure 48, hologram lens 142 are divided into a center 142a who is wherein drawing raster graphic P1, a pair ofly wherein drawing raster graphic P13, P14 so that eliminate side periphery district 142b, the 142c be included in the noise in the information signal, and a pair of no pattern district 142d, the 142e that do not reduce light intensity that does not wherein have picture raster graphic.Because raster graphic P1 is drawn in the hologram lens 142, is made of the complex objective lens 144 with two focuses hologram lens 142 and object lens 27.The optical axis of optical head device 141 passes the central point of raster graphic P1 and the central shaft of object lens 27.
Photodetector 143 comprises the sector optical detector 64 with detecting area SE7 to SE10, a pair of noise removing photodetector 138a, the 138b that is used for surveying the light intensity of the periphery district 142b, the 142c that pass hologram lens 142.
In above structure, the transmitted light L4 that generates in the 142a of the center of hologram lens 142 (or diffraction light L5) is focused at first information medium 23 (or second information medium 25) and goes up to form focal point S1 (or S2) on emitting light path.After this, transmitted light L4R (or diffraction light L5R) passes same light path in opposite direction.In other words, transmitted light L4R (or diffraction light L5R) passes condenser 27 once more, and a part of transmitted light L4R without any the center 142a transmission of diffraction ground warp hologram lens 142 or a part of diffraction light L5R in the 142a of center by diffraction once more.After this, the collimated lens 134 of transmitted light L4R (or diffraction light L5R) can pass beam splitter 82 by coalescence.In this case, with the 7th embodiment in identical mode in transmitted light L4R (or diffraction light L5R), generate astigmatic aberration.After this, transmitted light L4R (or diffraction light L5R) is incident on the detecting area SE7 to SE10 of photodetector 143 upward to form the shape focal point S21 identical with the focal point S10 shown in Figure 29 A to 29C.Transmitted light L4R in detecting area SE7 to SE10 (or diffraction light L5R) becomes current signal SC26 to SC29.Thereby, with with the 7th embodiment in identical mode obtain the servosignal of image focu error signal and tracking error signal and so on so that adjust the position of complex objective lens 144 so that transmitted light L4 (or diffraction light L5) focusing is focused on the information medium 23 (or 25).Moreover, obtain being recorded in information signal on second information medium 25 according to formula (14).
Sin＝SC26+SC27+SC28+SC29(14)
Moreover, a part be incident on incident light L3 on the periphery district 142b of hologram lens 142 without any diffraction ground warp periphery district 142b transmission forming a branch of periphery light L15, and a part be incident on incident light L3 on the periphery district 142c of hologram lens 142 without any diffraction ground warp periphery district 142c transmission to form a branch of periphery light L16.After this, periphery light L15, L16 are focused on the information medium 23 to form the focal point around focal point S1.After this, passed same light path in opposite direction by noise removing light L15R, the L16R of 23 reflections of first information medium.In other words, periphery light L15R, L16R pass condenser 27 once more.Part periphery light L15R diffracted and convergence in the periphery district of hologram lens 142 142b, to form a branch of noise removing light L15R, this noise removing light L15R is incident on the noise removing photodetector 138a, and a part of noise removing light L16R diffracted and convergence in the periphery district of hologram lens 142 142c, to form a branch of noise removing light L16R, this noise removing light L16R is incident on the noise removing photodetector 138b.In photodetector 138a, according to the intensity generation output signal SC30 of noise removing light L15R.Moreover the intensity according to noise removing light L16R in photodetector 138b generates output signal SC31.After this, by according to formula (15) all signal plus being obtained representing the information signal Snc of the noise removing that is recorded in information on the first information medium 23:
Snc＝(SC26+SC27+SC28+SC29)+R×(SC30+SC31)
(15)
Symbol R is a weight factor in the formula.
Therefore owing to use complex objective lens in the optical head device 141 with two focuses, can be from reliable recording on the information medium or reproduction message segment, and no matter information medium be actually thick be thin.
Moreover, can with the 14 embodiment in identical mode improve signal to noise ratio (S/N ratio) among the information signal Snc.
Moreover, even message segment is recorded on the slim high density compact disc by first information medium 23 representatives thick and fast, also can reappear information signal Snc reliably with very high signal to noise ratio (S/N ratio).
Moreover, photodetector 138a, 138b are last to be lowered by noise removing light L15R, L16R are focused at owing to be incident on light L4R on the detecting area SE7 to SE10 of photodetector 143 or the intensity of L5R, and the bearing accuracy of photodetector 143 can be relaxed and is reduced to 1/100.
Moreover, at raster graphic P13, the P14 of periphery district 142b, 142c the incident light L3 of diffraction in periphery district 142b, 142c is risen under the situation of lensing, form the bigger focal point that defocuses at first information medium 23 at the unnecessary diffraction light that in periphery district 142b, 142c, generates on the emitting light path by diffraction to incident light L3.And, to compare with the numbered of district 135b among the 14 embodiment, the numbered of each periphery district 142b, 142c is lowered, because hologram lens 142 are divided into many zones.Thereby the size of focal point that defocuses the unnecessary diffraction light of formation on first information medium 23 becomes bigger than among the 14 embodiment.As a result, the message segment that more is recorded on the first information medium 23 is read by unnecessary diffraction light, even and unnecessary diffraction light be incident on the photodetector 143, this information is also handled as one section average information in photodetector 143.Therefore, further average by the information quilt that unnecessary diffraction light is read, and average information does not have harmful effect as noise to information signal Snc.
Moreover, as shown in Figure 49 A, 49B, can prevent that unnecessary diffraction light is incident on the photodetector 64, each detecting area SE7 to SE10 has the square size of SL0 in this photodetector 64.In detail, diffracted once more to form a branch of unnecessary diffraction light Lu in periphery district 142b at the light that in periphery district 142c, generates on the emitting light path 1Situation under, light Lu 1Be focused at from the center of photodetector 64 SP1 (on the primary importance PT1 of SP1＞SL0).Diffracted once more to form a branch of unnecessary diffraction light Lu in periphery 142c at the light that in periphery district 142b, generates on the emitting light path 2Situation under, light Lu 2Be focused at from the center of photodetector 64 SP2 (on the second place ST2 of SP2＞SL0).Diffracted to form unnecessary diffracted beam Lu in identical periphery district 142b, 142c once more at the light that in periphery district 142b, 142c, generates on the emitting light path 3, Lu 4Situation under, light Lu 3, Lu 4Be focused at that (SP3＞SL0), SP4 are (on the third and fourth position PT3, the PT4 of SP4＞SL0) from the center of photodetector 64 SP3.Therefore, can prevent unnecessary diffraction light Lu 1To Lu 4Harmful effect.
Under the situation that light source 52 is made of semiconductor laser, the far-field pattern that is incident on the incident light L3 on the hologram lens 142 distributes by the Gaussian distribution shown in Figure 13 A, and the xsect beam profile of the incident light L3 that distributes by Gaussian distribution is for oval.In other words, incident light L3 is in the beam divergence angle (or full-shape of half-shadow general goal) of the vertical direction angle of divergence greater than horizontal direction.In this embodiment, the vertical direction of incident light L3 is pointed to the X2 direction shown in Figure 48, and the horizontal direction of incident light L3 is pointed to the Y2 direction shown in Figure 48.In this case, because district 142b, 142c be to the efficiency of transmission of the incident light L3 efficiency of transmission less than district 142d, 142e, reduce with comparing in the horizontal direction greatly in vertical direction without any the intensity of the incident light L3 of diffraction ground warp hologram lens 142 transmissions.Thereby the xsect beam profile of incident light L3 is modified into circle in hologram lens 142, and in other words, the focal point S1 that forms on first information medium 23 is modified into circle.Therefore, the secondary maximum (or side wave lobe) that occurs around focal point S1 can reduce, and the signal to noise ratio (S/N ratio) of information signal Snc can improve.
In the 15 embodiment, obtain the information signal Snc of noise removing according to formula (15).Yet preferably by formula (16) obtain the information signal Snc of noise removing:
Snc＝(SC26+SC27+SC28+SC29)+(R1×SC30+R2×SC31)(16)
Symbol R in the formula 1, R 2It is weight factor.In this case, can further reduce noise in the information of being included in.
(the 16 embodiment)
Contrast Figure 50,51 describes the optical head device of making small size and steady operation according to sixteenth embodiment of the invention.
Figure 50 is the constitutional diagram according to the optical head device of the 16 embodiment.Figure 51 is used for the light source of the optical head device shown in Figure 50 and the axonometric drawing of photodetector.
As shown in Figure 50, be used for or comprise the light source 52 that is used for launching along the incident light L3 of the no diffraction direction linear polarization parallel from the optical head device 151 of information medium 23 or 25 records or reproduction message segment with the X3 axle, be used on the emitting light path without any diffraction ground transmission incident light L3 and on input path diffraction along the transmitted light L4R of the diffraction direction linear polarization parallel or the hologram 152 of diffraction light L5R with the Y3 axle, collimation lens 53,1/4-λ substrate 69, hologram lens 26 (or 26M, 32,33,42,135 or 142), object lens 27, actuating unit 58, and be used for surveying photodetector 153 by the intensity of the light L4R of hologram 152 diffraction or L5R.
As shown in Figure 51, light source 52 and photodetector 153 are arranged on the substrate 154 so that the relative position between fixed light source 52 and the photodetector 153 critically.Photodetector 153 comprises that the sextant photodetector 59 that has detecting area SE1 to SE6 and tracking illumination electric explorer 60a are to 60d.Moreover, arrange a specular components 155 on the substrate 154 so that the incident light L3 from light source 52 emissions is guided into the Z3 direction.
Hologram 152 by lithium niobate substrate the proton exchange surface portion or utilize liquid crystal cell to make, as interim announcement the 189504/86th (clear and 61-189504) number and interim the announcement described in the 241735/88th (clear and 63-241735) number.Thereby the light of the no diffraction direction linear polarization that the edge is parallel with the X3 axle does not have 152 transmissions of diffraction ground warp hologram.Different therewith, along with perpendicular to the light of the parallel diffraction direction linear polarization of the Y3 axle of X3 axle by hologram 152 diffraction.
In above structure, the incident light L3 of the no diffraction direction linear polarization that the edge is parallel with the X3 axle is from light source 52 emission friendships and without any 152 transmissions of diffraction ground warp hologram.After this, the collimated lens 53 of incident light L3 are aimed at, and linear polarization incident light L3 is become circularly polarized incident light L3 by 1/4 1 λ sheets 69.After this, a part of incident light L3 without any 26 transmissions of diffraction ground warp hologram lens forming transmitted light L4, and remainder incident light L3 by hologram lens 62 diffraction to form diffraction light L5.After this, light L4, L5 are assembled by object lens 27, and go up the focal point S1 (or focal point S2 of diffraction light L5) that forms transmitted light L4 at first information medium 23 (or second information medium 25).When light L4 or L5 were reflected by information medium 23 (or 25) and become light L4R (or L5R), circularly polarized sense of rotation was reverse among the light L4.Thereby the light L4R (or L5R) with opposite circular polarization passes same light path in opposite direction.In other words, transmitted light L4R (or diffraction light L5R) passes condenser 27 once more, and a part of transmitted light L4R without any lens 142 transmissions of diffraction ground warp hologram or a part of diffraction light L5R once more by hologram lens 142 diffraction.After this, the lens light L4R of opposite circular polarization (or diffraction light L5R) is become along the light L4R (or L5R) of the diffraction light direction linear polarization parallel with the Y3 axle by 1/4-λ sheet 69.After this, the collimated lens of light L4R (or L5R) 53 can coalescences by hologram 152 diffraction so that on photodetector 153, form a plurality of focal points.Thereby, in photodetector 153, obtain representative and be recorded in the information signal of the segment information on the information medium 23 (or 25) and the servosignal of image focu error signal and tracking error signal and so in the mode identical with the 6th embodiment.
Therefore owing in optical head device 151, use complex objective lens with two focuses, can or from the information medium reliable recording or reproduction message segment, and no matter information medium be actually thick be thin.
Moreover, since all incident light L3 on the emitting light path through hologram 152 transmissions and since all light L4R or L5R on input path by hologram 152 diffraction, can improve the utilization factor of incident light L3.Thereby, even the emissive porwer of incident light L3 is very low in the light source 52, also can obtain having the information signal and the servosignal of high s/n ratio reliably.
Moreover, owing in optical head device 151, do not use beam splitter, can be with small size, light weight and the low-cost optical head device 151 of making.
Moreover, because the optical element of optical head device 151 arranges along its optical axis,, also can obtain the optical head device 151 of steady operation even temperature changes and device when working long hours significantly around.
Moreover, owing to need preferably not improve the diffraction efficiency of hologram 152 so that the efficiency of transmission of hologram 152 almost is set as zero without any the light L4R or the L5R of 152 transmissions of diffraction ground warp hologram on input path.In this case, the button of hologram 152 and 1/4-λ sheet 69 functions closes the isolator effect and returns light source 52 to prevent light L4R or L5R.Thereby, doing to return the active layer of semiconductor laser without any light under the situation of light source 52 with semiconductor laser.Thereby, can prevent to be returned the noise that light brought out of semiconductor laser.
Moreover because light source 52 and photodetector 153 are arranged on the same substrate 154, light source 52 and photodetector 153 can closely be arranged mutually.Thereby the relative position between light source 52 and the photodetector 153 can be determined with high precision at an easy rate.For example, relative position can be determined with interior precision with a few μ m.Therefore, can reduce the manufacturing cost of optical head device 151, and optical head device 151 can be made with small size, light weight and low cost further.
Moreover light source 52 is electrically connected by first lead and external circuit, and photodetector 153 is electrically connected by second lead and another external circuit.In this case, because light source 52 and photodetector 153 are arranged on the same substrate 154, first lead and second lead can pass the X3-Y3 plane simultaneously.Thereby light source 52 can be easy to automatically be connected with external circuit with photodetector 153.In addition, only be drawn on the X3-Y3 plane because light source 52 and photodetector 153 are connected required reference line with external circuit, the relative position between light source 52 and the photodetector 153 can be determined with high precision at an easy rate.
In the 16 embodiment, the optical head device 151 that has hologram 152 has been described.Yet, under the enough big situation of the intensity of incident light L3, also can replace hologram 152 to use hologram or blazed hologram with little grating grid.In this case, can or from the information medium reliable recording or reproduction message segment, no matter and information medium be actually thick be thin.Moreover owing to do not use beam splitter in optical head device 151, optical head device 151 can be made with small size, light weight and low cost.Moreover, because the optical element of optical head device 151 arranges along its optical axis,, also can obtain the optical head device 151 of steady operation even when environment temperature changes significantly and device works long hours.
(the 17 embodiment)
Contrast Figure 52 describes the optical head device of making small size and steady operation according to seventeenth embodiment of the invention.
Figure 52 is the constitutional diagram according to the optical head device of the 17 embodiment.
As shown in Figure 52, be used for or from information medium 23 25 the record or the reproduction message segment optical head device 161 comprise the light source 52 that is used for launching along the incident light L3 of first direction linear polarization, collimation lens 53, being used for of forming on the front surface of transparent substrate 162 reflected along the incident light L3 of first direction linear polarization and transmission along the polarisation of light color separation film (Separation film) 162 perpendicular to the second direction linear polarization of first direction, 1/4-λ sheet 69, hologram lens 26 (or 26M, 32,33,42,135 or 142), object lens 27, actuating unit 58, what form on the rear surface of transparent substrate 162 is used for diffraction and reflected light L4R, reflective holographic Figure 164 of L5R, and photodetector 57.
In above structure, 52 emissions along the incident light L3 of first direction linear polarization from light source, and collimated lens 53 are aimed at.After this, all incident light L3 are polarized color separation film 162 reflections, because incident light L3 is along the first direction linear polarization.Thereby incident light L3 points to direction up.After this, the linear polarization of incident light L3 becomes circular polarization in 1/4-λ sheet 69, and a part of incident light L3 through 26 transmissions of hologram lens to form transmitted light L4.Moreover, remainder incident light L3 by hologram lens 26 diffraction to form diffraction light L5.After this, light L4, L5 are assembled by object lens 27, and go up the focal point S1 (or focal point S2 of diffraction light L5) that forms transmitted light L4 at first information medium 23 (or second information medium 25).After this, the transmitted light L4R of opposite circular polarization (or diffraction light L5R) with the 16 embodiment in identical mode pass condenser 27 once more, and a part of transmitted light L4R without any 26 transmissions of diffraction ground warp holographic lens or a part of diffraction light L5R once more by hologram lens 26 diffraction.After this, the transmitted light L4R of opposite circular polarization (or diffraction light L5R) is become the light L4R (or L5R) of edge perpendicular to the second direction linear polarization of first direction by 1/4-λ sheet 69.After this, all light L4R (or L5R) are polarized color separation film 162 refraction and by holographic Figure 164 diffraction and reflection.After this, light L4R (or L5R) assembles so that form a plurality of focal points on photodetector 57 through 162 transmissions of polarization color separation film and collimated lens 53.Thereby, in photodetector 57 with the 6th embodiment in identical mode obtain representative and be recorded in the information signal of the segment information on the information medium 23 (or 25) and the servosignal of image focu error signal and tracking error signal and so on.
Therefore owing to use complex objective lens in the optical head device 161 with two focuses, can or from the information medium reliable recording or reproduction message segment, and no matter information medium be actually thick be thin.
Moreover, because the incident light L3 that is incident on the polarization color separation film 162 collimates, on whole diaphragm 162, be uniform to the reflectivity of incident light L3.Thereby, be easy on information medium 23 or 25 to form the diffraction-limited spot of light L4 or L5.Moreover, because the L4R, the L5R that are incident on the polarization color separation film 162 collimate, be uniform on whole 162 to the transmissivity of light L4R, L5R.Thereby, can prevent the skew that in servosignal, occurs.
Moreover, since all incident light L3 on the emitting light path through holographic Figure 164 transmission and since all light L4R, L5R on input path by holographic Figure 164 diffraction, can improve the utilization factor of incident light L3.Thereby, even the emissive porwer of incident light L3 is low in the light source 52, also can obtain having the information signal and the servosignal of high s/n ratio reliably.
Moreover because the hybrid element of being made up of sheet 162, substrate 163 and holographic Figure 164 plays beam splitter and the effect of growth (rising) mirror, optical head device 161 can be made with small size, light weight and low cost.
Moreover, because the optical element of optical head device 161 arranges along its optical axis,, also can obtain the optical head device 161 of steady operation even temperature changes and device when working long hours significantly around.
Moreover the combination of sheet 162 and 1/4-λ sheet 69 functions plays the isolator effect and returns light source 52 to prevent light L4R or L5R.Thereby, doing to turn back to the active layer of semiconductor laser without any light under the situation of light source 52 with semiconductor laser.Therefore, can prevent by the photo-induced noise that turns back to semiconductor laser.
Moreover holographic Figure 164 preferably glitters.In this case, owing to prevent from holographic Figure 164 to generate the unnecessary diffraction light of negative first-order diffraction light of picture and so on, holographic Figure 164 becomes first-order diffraction diffraction of light efficient to light can be set as almost 100%.Thereby, can effectively utilize incident light L3 to obtain signal.
Moreover, being diffracted into first-order diffraction light owing to be incident on the light of hologram 10A, the chromatic aberration that occurs among light L4R, the L5R can be compensated in hologram 16A.Thereby, can be stable obtain servosignal.
In the 17 embodiment, collimation lens 53 is arranged between light source 52 and the sheet 162.Yet, collimation lens 53 in optical head device 161 not necessarily.
Moreover, the optical head device that has sheet 162 and 1/4-λ sheet 69 has been described.Yet, under the enough big situation of the intensity of incident light L3, also can replace sheet 162 to use and have the reflector plate of about 1/3 reflectivity and save 1/4-λ sheet 69.In this case, can or from the information medium reliable recording or reproduction message segment, and no matter information medium be actually thick be thin.Moreover because the hybrid element that sheet 162, substrate 163 and holographic Figure 164 form plays beam splitter and increases the mirror effect, optical head device 161 can be made with small size, light weight and low cost.Moreover, because the optical element of optical head device 161 arranges along optical axis,, also can obtain the optical head device 161 of steady operation even temperature changes and device when working long hours significantly around.
In the 6th to the 17 embodiment, can or from the information medium reliable recording or reproduction message segment, actually or and no matter the conventional CD of CD and so on of information medium representative picture with thickness of about 1.2mm have from the following high density compact disc of the thickness of 0.4mm to 0.8mm scope.Yet, or during from information medium record or reproduction information, need the thickness of fox message medium in advance.Thereby, writing down under the situation of one section identifying information with the thickness of identifying information medium on the information medium, be very easily in advance to the user.Owing on conventional CD, be provided with the record identifying information, be preferably on the following high density compact disc that occurs on the future market and write down identifying information.Thereby, the high density compact disc that has identifying information is described according to the 18 and the 19 embodiment.
(the 18 embodiment)
Figure 53 is the axonometric drawing according to the high density compact disc of the 18 embodiment, the sectional view of local indicating panel.
As shown in Figure 53, high density compact disc 171 is divided into outskirt 171a and inner region 171b.Outskirt 171a occupies the major part of CD 171, and the information of outskirt 171a record substrate 171c has thickness T 1, and the information record substrate 171c of inner region 171b has thickness T 2.On the information record substrate 171c of outskirt 171a, form a plurality of first record pits 172 successively so that with the high density recording message segment with narrow interval.Moreover, on the information of inner region 171b record substrate 171c, form a plurality of second record pits 173 successively so that with the common density record identifying information section of CD with the normal interval.Identifying information informs that CD 171 has thickness T 1.The thickness T 1 of outskirt 171a does not for example wait from 0.4mm to 0.8mm, and the thickness T 2 of inner region 171b for example is about 1.2mm.
In above structure, be focused at first on the inner region of information medium 23,25 according to the diffraction light L5 of first or second embodiment (or according to the 3rd embodiment transmitted light L4), carry out simultaneously and the corresponding focus control of second information medium 25 with thickness T 2.At information medium 23 or 25 is under the situation of CD 171, detects to inform that the CD with thickness T 1 is by one section identifying information of light L5 (or L4) convergence.After this, transmitted light L4 (or diffraction light L6) automatically is focused on the outskirt 171a of CD 171, carries out the focus control corresponding with the first information medium 23 with thickness T 1 simultaneously.
Different therewith, be to have under the situation of the conventional CD of thick type of thickness T 2 at information medium 23 or 25, the inner region 171b that is focused at conventional CD as light L5 (or L4) surveys less than identifying information when going up.In this case, proceed the focus control corresponding, so that survey the information signal that representative is recorded in the segment information on the conventional CD with second information medium 25.
Therefore, under the situation of using one of optical head device shown in Figure 21,27,30,31,32,33,37,38, the 40A, 43,44,50 and 52, can or from the information medium record or reproduction message segment automatically, and no matter information medium be actually thick be thin.
Moreover owing to only write down identifying information in inner region, inner region can be very little.Thereby the memory capacity of CD 171 does not reduce because of increasing by the second record pit 173.
(the 19 embodiment)
Figure 54 is the axonometric drawing according to the high density compact disc of the 19 embodiment, the sectional view of local indicating panel.
As shown in Figure 54, high density compact disc 174 is divided into outskirt 174a and inner region 174b.Outskirt 174a occupies the major part of CD 174.CD 174 has homogeneous thickness T1.On the information record substrate 174c of outskirt 174a, form the first record pit 172 so that with the high density recording message segment.Moreover, on the information of inner region 174b record substrate 174c, form and a plurality ofly have large-sized second record pit 175 so that with the density record identifying information section lower than normal density with wide interval.Identifying information informs that whole CD 174 has thickness T 1.For example the thickness T 1 of CD 174 does not wait from 0.4mm to 0.8mm.
In above structure, be focused at first on the inner region of information medium 23 or 25 according to the diffraction light L5 of first or second embodiment (or according to the 3rd embodiment transmitted light L4), carry out simultaneously and the corresponding focus control of second information medium 25 with thickness T 2.At information medium 23 or 25 is under the situation of CD 174, and light L5 (or L4) defocuses and is focused on each second record pit 175.Yet, because each second record pit 175 size and very big writes down the focal point that forms light L5 (or L4) in one of pit 175 reliably second.Thereby, detect and inform that the CD 174 with thickness T 1 is by one section identifying information of light L5 (or L4) convergence.After this, transmitted light L4 (or diffraction light L6) automatically is focused on the outskirt 174a of CD 174, carries out the focus control corresponding with the first information medium 23 with thickness T 1 simultaneously.
Different therewith, be to have under the situation of the conventional CD of thick type of thickness T 2 at information medium 23 or 25, the inner region 174b that is focused at conventional CD as light L5 (or L4) surveys less than identifying information when going up.In this case, proceed the focus control corresponding, so that survey the information signal that representative is recorded in the segment information on the conventional CD with second information medium 25.
Therefore, under the situation of using one of optical head device shown in Figure 21,27,30,31,32,33,37,38, the 40A, 43,44,50 and 52, can or from the information medium record or reproduction message segment automatically, and no matter information medium be actually thick be thin.
Moreover owing to only write down identifying information in inner region, inner region can be very little.Thereby the memory capacity of CD 174 does not reduce because of increasing by the second record pit 173.
(the 20 embodiment)
A kind of optical disc apparatus that has the optical head device is described, high density compact disc that control is automatically used actually in the optical head device or conventional CD with thickness T 2 with thickness T 1.
Figure 55 is the calcspar according to the optical disc apparatus that has one of optical head device shown in Figure 21,27,30,31,32,33,37,38, the 40A, 43,44,50 and 52 of the 20 embodiment.Figure 56 is the workflow diagram of the optical disc apparatus shown in expression Figure 55.
As shown in Figure 55, be used for or comprise optical head device 51 (or 61,65,67,70,71,81,91,101,111,121,151 or 161) from the optical disc apparatus 176 of high density compact disc 171 (or 174) or conventional CD 25 records or reproduction message segment, mobile device 177 that is used for optical head device 51 is moved on to the precalculated position, and a whirligig 178 that is used for rotating high density compact disc 171 (or 174) or conventional CD 25 as spindle drive motor and so on as feed mechanism and so on.
In above structure, high density compact disc 171 or conventional CD 25 are placed in the precalculated position of optical disc apparatus 176, and CD 171 or 25 is rotated device 178 rotations.After this, optical head device 51 just is moved to the position under the inside recording track of CD 171 or 25 in step 211, and diffraction light L5 is focused on the inside recording track of CD 171 or 25 in step 212, carries out the focus control corresponding with the conventional CD 25 with thickness T 2 simultaneously.After this, in step 213, carry out tracking Control, and survey the segment information on the inside recording track be recorded in CD 171 or 25.After this, judge that in step 214 information is whether with to inform that the CD 171 with thickness T 1 is placed in one section identifying information of optical disc apparatus 176 consistent.
Be placed at high density compact disc 171 under the situation of optical disc apparatus 176, detect identifying information.After this, transmitted light L4 automatically is focused on the CD 171 in step 215, carries out the focus control corresponding with the CD 171 with thickness T 1 simultaneously.Thereby, or from CD 171 record or reproduction message segment.
Different therewith, be placed under the situation of optical disc apparatus 176 at conventional CD 25, survey less than identifying information.In this case, in step 216, continue diffraction light L5 is focused on the conventional CD 25, carry out focus control and the tracking Control corresponding simultaneously with conventional CD 25.Thereby, or from conventional CD 25 records or reproduction message segment.
Therefore, can judge the thickness of the CD that places optical disc apparatus 176 accurately rapidly.Moreover, can or from the CD stably record or reproduction message segment, actually and no matter CD high density compact disc 171 (or 174) or conventional CD 25.
(the 21 embodiment)
Describe a kind of optical disc apparatus that has an optical head device, in this optical disc apparatus, automatically judge high density compact disc that actually uses or conventional CD with thickness T 2 with thickness T 1.
Figure 57 is the calcspar according to the optical disc apparatus that has one of optical head device shown in Figure 21,27,30,31,32,33,37,38, the 40A, 43,44,50 and 52 of the 21 embodiment.Figure 58 is the workflow diagram of the optical disc apparatus shown in expression Figure 57.
As shown in Figure 57, be used for or comprise optical head device 51 (or 61,65,67,70,71,81,91,101,111,121,151 or 161) from the optical disc apparatus 176 of high density compact disc 182 or conventional CD 25 records or reproduction message segment, mobile device 177, and a whirligig 182 that is used for rotating high density compact disc 182 or conventional CD 25 as spindle drive motor and so on.High density compact disc 182 does not have identifying information and has thickness T 1.
In above structure, high density compact disc 182 or conventional CD 25 are placed in the precalculated position of optical disc apparatus 181, and CD 182 or 25 is rotated device 182 rotations.After this, optical head device 51 just is moved to the position under the inside recording track of CD 182 or 25 in step 221, because reliable recording one segment information on the inside recording track, and diffraction light L5 is focused on the inside recording track of CD 182 or 25 in step 222, carries out the focus control corresponding with the conventional CD 25 with thickness T 2 simultaneously.After this, in step 223, carry out tracking Control and survey and be recorded in a segment information on the inside recording track of CD 182 or 25.After this, judge that in step 224 whether the intensity of the information signal of representing institute's detection information is greater than threshold value.In other words, represent diffraction light L5 to focus on greater than the intensity of the information signal of threshold value and be focused on CD 182 or 25, and on behalf of diffraction light L5, the intensity that is not more than the information signal of threshold value defocus to be focused on CD 182 or 25.
Be placed at high density compact disc 182 under the situation of optical disc apparatus 181, detect the information signal intensity that is not more than threshold value.In this case, transmitted light L4 automatically is focused on the CD 182 in step 225, carries out the focus control corresponding with the high density compact disc 182 with thickness T 1 simultaneously.Thereby, or from CD 182 record or reproduction message segment.
Different therewith, be placed under the situation of optical disc apparatus 181 at conventional CD 25, detect information signal intensity greater than threshold value.In this case, diffraction light L5 continues to be focused on the conventional CD 25 in step 226, carries out focus control and the tracking Control corresponding with conventional CD 25 simultaneously.Thereby, or from conventional CD 25 records or reproduction message segment.
Therefore, even do not use CD 171 or 174 can judge the disk thickness that places optical disc apparatus 181 yet.Moreover, can or from the CD stably record or reproduction message segment, actually or and CD high density compact disc 182 conventional CDs 25 no matter.
(the 22 embodiment)
Describe a kind of bifocus microscope according to the 22 embodiment, in this microscope, observe two of on Different Plane, forming simultaneously and resemble with two focuses.
Figure 59 is according to the microscopical constitutional diagram of the bifocus of the 22 embodiment.
As shown in Figure 59, be used for observing simultaneously bifocus microscope 191 that first of the first exemplar SP1 that places on the first exemplar plane P L1 resembled and placed second elephant of the second exemplar SP2 on the second exemplar plane P L2 and comprise that one has to be used for reflecting and a branch ofly resembles from first that the first smooth L17 that disperses and refraction are a branch of to resemble the second smooth L18's that disperses from second.Object lens 192 with first focal length F1, be used for without any a diffraction ground transmission part first smooth L17 and a diffraction part second smooth L18 so that make the second smooth L18 pass hologram lens 26 (or the 26M of the same light path that the first smooth L17 passed, 32,33 or 42), one is used for a branch of by first light and the second smooth L17, the interior lens 193 of focus Pf1 in the superimposed light L19 that L18 forms converges at, an eyepiece 194 that is used for forming simultaneously first and second elephants by assembling the folded light L19 that disperses from interior focus Pf1, one is used for moving the composition element of interior lens 193 and hologram lens 26 so that adjust the interior lens barrel 195 of the distance between composition element and the eyepiece 194 along optical axis, and is used for moving object lens 192 so that the first exemplar plane P L1 is become the outer lens lens barrel 196 of the focal length F1 of object lens 192 with the distance setting between the object lens 192 along optical axis.
Optical axis passes the center of object lens 192, hologram lens 26, interior lens 195 and eyepiece 194.The position that is different from the second exemplar plane P L2 along the position of the optical axis first exemplar plane P L1.
In above structure, the position of adjusting object lens 192 is so that become the first exemplar plane P L1 the first focal length F1 of object lens 192 with the distance setting between the object lens 192.In this case, the distance between the second exemplar plane P L2 and the object lens 192 is configured to the second focal length F2.Moreover the position of adjusting composition element is so that see that clearly first and second resemble.In other words, a branch of first resembling the first smooth L17 that disperses and object lens 192, be aligned from the first exemplar plane P L1, and also a part first smooth L17 is through 26 transmissions of hologram lens.Moreover, a branch of second resembling the second smooth L18 that disperses and object lens 192, be refracted from the second exemplar plane P L2, and a part second smooth L18 is diffracted so that make the second smooth L18 pass the same light path that the first smooth L17 is passed in hologram lens 26.Thereby, form a branch of superimposed light L19 by the first and second smooth L17, L18.After this, focus Pf1 in superimposed light L19 is converged at by interior lens 193 so as first to resemble and second resemble of on image plane PL3, form amplifying simultaneously and assembled by eyepiece 194 so that on operator's eyes, form first resembling and second resemble of amplifying simultaneously from the superimposed light L19 that a Pf1 disperses.
Therefore, owing to form superimposed light L19, resemble and place second of the second exemplar SP2 on the second exemplar plane P L2 to resemble by bifocus microscope 191 being focused on simultaneously last first of the first exemplar SP1 that places on the first exemplar plane P L1 that can observe simultaneously of the first and second exemplar SP1, SP2 with hologram lens 26,26M, 32,33 or 42.
Moreover, even the strength degradation of the first and second smooth L17, L18 when light L17, L18 pass the hologram lens, the intensity of stack L19 also is enough for observation first and second resembles, because the intensity of superimposed light L19 depends on the first and second light intensity sums.
Moreover, because hologram lens 26 glitter as shown in Figure 6, when the second smooth L18 is diffracted in hologram lens 26, can reduce the generation of the unnecessary diffraction light of negative first-order diffraction light of picture and so on.Thereby, can improve the intensity of superimposed light L19, so that viewed first and second resemble can be brighter.
Moreover, as shown in Figure 60, be placed on the bottom of the first exemplar platform 197 and the second exemplar SP2 is placed under the situation of the bottom that is positioned at the second sample platform 198 below the first exemplar platform 197 at the first exemplar SP1, owing in the first exemplar platform 197, the light path of the first smooth L17 is different from the first and second exemplar platforms 197,198 light path of the second smooth L18, in the first and second smooth L17, the L18 that is incident on object lens 192, generates aberration as chromatic aberration and so on.Yet, by in hologram lens 26 as described in first embodiment to the surplus correction of chromatic aberration, can in hologram lens 26, eliminate aberration.
Moreover, can change the poor of first and second focal length by moving inside and outside lens barrel 195,196, because changed the distance between hologram lens 26 and the object lens 192.Thereby, even the thickness of the second exemplar platform 198 changes, still can observe first and second reliably and resemble.
In the 22 embodiment, in bifocus microscope 191, use eyepiece 194.Yet eyepiece 194 not necessarily.Moreover as shown in Figure 61, the camera 199 of image charge coupled apparatus (CCD) camera and so on can replace eyepiece 194 to be located on the image plane PL3.In this case, available CCD camera 199 is taken the stack that is become by first and second pictographs that amplify and is resembled, and consequently can write down first and second simultaneously and resemble.
(the 23 embodiment)
Forming under the situation of microcircuit on the semiconductor wafer, on semiconductor wafer, apply photochromics, and in exposure-processed, with ultraviolet light the photochromics that is coated on the semiconductor wafer is exposed by the photomask that has mask graph.Thereby the mask graph of photomask is transferred on the photochromics.In this case, with very high precision semiconductor wafer is aimed at photomask in the registration process that need before exposure-processed, carry out, thereby, observe the reference that is drawn on the semiconductor crystal sheet simultaneously with the conventional microscope with dark depth of focus and resemble and be drawn in mask graph on the photomask.Yet,, can not resemble reference with mask graph with interior precision with 5 μ m and aim at owing to the conventional microscopical magnification with dark depth of focus is very low.
In order to solve above shortcoming in the present invention, a kind of alignment device that is used for registration process according to the 23 embodiment is described, in this device, when observing the reference be drawn on the semiconductor wafer at the same time and resemble and be drawn in mask graph on the photomask, the semiconductor crystal sheet is aimed at photomask with high precision.
Figure 62 is the constitutional diagram according to the alignment device of the 23 embodiment.
As shown in Figure 62, be used for first comprising that with reference to resembling alignment device 201 that RF2 aims at one is used for dispersing the alignment with specific wavelength and resembles RF1 to illuminate first and second references to what be drawn in mask graph on photomask 202 lower surfaces with being drawn in as second on the lower surface of the exemplar of semiconductor chip 203 and so on reference to resembling RF1, the light source 204 of RF2, be used for receiving a branch of from be aligned illumination bright first with reference to resemble the first alignment light L20 that RF1 disperses and receive a branch of from be aligned illumination bright second with reference to the object lens 192 that resemble the second alignment light L21 that RF2 disperses, be used for without any a diffraction ground transmission part first alignment light L20 and a diffraction part second alignment light L21 so that make the second alignment light L21 pass hologram lens 26 (or the 26M of the same light path that the first alignment light L20 passed, 32,33 or 42), be used for the stack alignment light L22 that is formed by the first alignment light L20 and the second alignment light L21 is focused at the interior lens 193 of interior focus Pf2, in being located at of image charge coupled apparatus (CCD) camera and so on focus Pf2 place be used for take and write down first and second references simultaneously and resemble RF1, the camera 205 of RF2, interior lens barrel 195, outer lens lens barrel 196, be used for along the horizontal direction vertical with optical axis move photomask 202 in case first with reference to resemble RF1 with second the reference resemble the mobile device 206 of RF2 along optical axis alignment, and be used for the basis be recorded in first and second in the camera 205 with reference to figure RF1, RF2 controls the control device 207 of the motion of photomask 202.
The specific wavelength of alignment light is determined according to the sufficiently high condition of transmissivity of 203 pairs of alignment light of semiconductor chip.Optical axis passes the center of object lens 192, hologram lens 26 and interior lens 193.
With with the 22 embodiment in same way as bifocus microscope 208 by object lens 192, hologram lens 26 (or 26M, 32,33 or 42), interior lens 193, interior lens barrel 195 and outer lens lens barrel 196 formed.
In above structure, a branch ofly object lens 192, aim at, and a part of first alignment light L20 is through 26 transmissions of hologram lens from first with reference to resembling the first alignment light L20 that RF1 disperses.Moreover, a branch ofly object lens 192, reflect from second with reference to resembling the second alignment light L21 that RF2 disperses, and a part of second alignment light L21 by hologram lens 26 diffraction so that make the second alignment light L21 pass the same light path that the first alignment light L20 is passed.Thereby, form a branch of stack alignment light L22 by the first and second alignment light L20, L21.After this, focus Pf2 sentenced first and second references that just form amplification simultaneously and resembles RF1, RF2 in stack alignment light L22 converged at.After this, first and second of amplification taken and record by camera 205 with reference to resembling RF1, RF2.After this, in control device 207, check first and second with reference to the relative position that resembles between RF1, the RF2, and under the control of control device 207, move photomask 202 by mobile device 206 along continuous straight runs, so that aim at first with reference to resembling RF2 with second with reference to resembling RF1.
Therefore, because the bifocus microscope 208 that uses hologram lens 26,26M, 32,33 or 42 to have two focuses with formation also observes first with reference to resembling RF1 and second with reference to resembling RF2 simultaneously even the depth of focus of bifocus microscope 208 is very little.Moreover, because the depth of focus of bifocus microscope 208 can reduce, can improve the magnification of bifocus microscope 208.Thereby, can resemble first of photomask 202 RF2 with second reference of semiconductor chip 203 and aim at reference to resembling RF1 with high precision very.
With its most preferred embodiment diagram with described principle of the present invention, it is evident that for the professional and technical personnel the present invention can not break away from these principles in correct on the scheme and on the details.We declare all modifications and fall in the spirit and scope of appended claims.

Claims (19)

1. optic probe device, be used on beam convergence to two kind of information medium every kind, described two kinds of information mediums have the transparent part of different-thickness respectively, and described two kinds of information mediums comprise the first information medium of first transparent part with first thickness and have second information medium of second transparent part of second thickness, to write down or to reproduce a segment information, this optic probe device comprises:
Light source is used to launch light beam;
Collimation lens, being used for the described Beam Transformation from described light source is the light of almost parallel;
Optical lens, be used for receiving from the light of the described almost parallel of described collimation lens and assemble the light of described almost parallel by transparent part, this optical lens has a plurality of zones, described a plurality of zone comprises the first area and than the second area of the optical axis of the more approaching described optical lens in first area, wherein described at least second area has relief pattern, and this optical lens can be changed into the first kind of light beam that passes first area and second area simultaneously with this a branch of light of the almost parallel of described reception, and the second kind of light beam that only passes through second area, and the described light beam that passes first area and second area simultaneously is focused on the first information medium by first transparent part with first numerical aperture, and the described light beam that only passes second area is focused on second information medium by second transparent part with the second value aperture less than first numerical aperture; And
A photodetector is used for receiving from the light beam of every kind of described information medium and exports electric signal.
2. optic probe device as claimed in claim 1, wherein, first thickness of first transparent part of described first information medium is less than second thickness of second transparent part of described second information medium, and according to the described zone of dividing described optical lens from the difference of the distance of the optical axis of described optical lens.
3. optic probe device as claimed in claim 1, wherein, described relief pattern is formed in the second area of described optical lens with one heart.
4. optic probe device as claimed in claim 1, wherein, described relief pattern is arranged on a side opposite with described CD of described optical lens.
5. optic probe device as claimed in claim 1, wherein, the first area of described optical lens has relief pattern.
6. optic probe device as claimed in claim 5, wherein, the height of the relief pattern of described first area is greater than the height of the relief pattern of described second area.
7. optic probe device as claimed in claim 1, wherein said optical lens have object lens and asperities lens, and described asperities lens have described a plurality of zone.
8. optic probe device as claimed in claim 1, wherein, first thickness of first transparent part of described first information medium is greater than 0.4mm, less than 0.8mm.
9. optic probe device as claimed in claim 1, wherein, the relief pattern of described second area is a hologram.
10. optic probe device as claimed in claim 9, wherein, the hologram of described second area becomes according to the mode of convex lens works.
11. optic probe device as claimed in claim 9, wherein, the hologram of described second area has and forms stair-stepping part respectively, and described part tilts to form the surface of convex lens to identical direction.
12. optic probe device as claimed in claim 9, wherein, a plurality of zones of described optical lens comprise the zone that at least one does not have hologram.
13. optic probe device as claimed in claim 9, wherein, the described first area of described optical lens does not have hologram.
14. optic probe device as claimed in claim 9, wherein, the described first area of described optical lens has hologram.
15. optic probe device as claimed in claim 1, wherein, the height H that is formed at the described relief pattern in the described second area is set to:
H＜λ/(n(λ)-1)，
Wherein, sign of lambda represents to pass the light wavelength of the described almost parallel of described second area, and the material of the described relief pattern of symbol n (λ) expression is to the refractive index of the light wavelength λ of described almost parallel.
16. optic probe device as claimed in claim 15, wherein, the difference of phase modulation degree of light of described almost parallel of passing described second area is less than 2 π radians.
17. optic probe device as claimed in claim 9, wherein, the hologram of described second area becomes the blazed hologram lens.
18. optic probe device as claimed in claim 17, wherein, the cross section of described hologram forms serrate.
19. an optical disc apparatus comprises:
Optic probe device as claimed in claim 1;
Be used for moving the mobile device of described optic probe device; With
Be used to rotate the whirligig of every kind of described information medium.
CNB03104462XA 1993-08-04 1994-04-01 Optical head device and optical disk device Expired - Lifetime CN100369136C (en)

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JP193353/1993 1993-08-04
JP193353/93 1993-08-04
JP19335393 1993-08-04

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CNA2005100833317A Pending CN1707312A (en) 1993-08-04 1994-04-01 Objective lens,optical device and optical information system
CNB200610093211XA Expired - Lifetime CN100454046C (en) 1993-08-04 1994-04-01 Objective lens, optical head device, and optical disk device
CNB03104462XA Expired - Lifetime CN100369136C (en) 1993-08-04 1994-04-01 Optical head device and optical disk device
CN94103940A Expired - Lifetime CN1118803C (en) 1993-08-04 1994-04-01 Compound objective lens... with the binary focus microscope
CNB031044646A Expired - Lifetime CN100369137C (en) 1993-08-04 1994-04-01 Focusing control method and optical disk device
CNB031044638A Expired - Lifetime CN100369134C (en) 1993-08-04 1994-04-01 Focusing control method and optical disk device

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CNB200610093211XA Expired - Lifetime CN100454046C (en) 1993-08-04 1994-04-01 Objective lens, optical head device, and optical disk device

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CNB031044646A Expired - Lifetime CN100369137C (en) 1993-08-04 1994-04-01 Focusing control method and optical disk device
CNB031044638A Expired - Lifetime CN100369134C (en) 1993-08-04 1994-04-01 Focusing control method and optical disk device

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CN1098508A (en) 1995-02-08
CN1516141A (en) 2004-07-28
CN100369137C (en) 2008-02-13
CN100369134C (en) 2008-02-13
CN100454046C (en) 2009-01-21
CN1908701A (en) 2007-02-07
CN1516142A (en) 2004-07-28
CN1516140A (en) 2004-07-28
CN1118803C (en) 2003-08-20
CN1707312A (en) 2005-12-14

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