CN1291399C

CN1291399C - Optical reading/writing system

Info

Publication number: CN1291399C
Application number: CNB2004100280776A
Authority: CN
Inventors: 孙文信
Original assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Current assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Priority date: 2004-07-10
Filing date: 2004-07-10
Publication date: 2006-12-20
Anticipated expiration: 2024-07-10
Also published as: CN1719526A

Abstract

The present invention relates to an optical reading and writing system which can record and reproduce signals of a first, a second and a third optical disk specifications, and storage densities of the first, the second and the third optical disk specifications orderly and gradually increase. The optical reading and writing system comprises three light sources respectively generating a first, a second and a third incident light beams, three detecting elements arranged corresponding to the light sources, a collimating lens, an object lens and a prism unit provided with a first, a second and a third light inlet surfaces and a light outlet surface, wherein wave lengths of the first, the second and the third incident light beams are respectively the wave lengths determined by the first, the second and the third optical disk specifications. The first, the second and the third incident light beams respectively enter the prism unit by the first, the second and the third light inlet surfaces and are output by the same light outlet surface. An aspheric surface is respectively arranged in a light path that the first and the third incident light beams pass through by the prism unit. The collimating lens and the object lens both have optical parameters matched with the second optical disk specification.

Description

The optical read/write system

[technical field]

The invention relates to a kind of optical read/write system that is used for data recording/reproducing device, refer to a kind of optical read/write system that is used for the high density recording/transcriber of compatible multiple CD specification especially.

[background technology]

The optical read/write system focuses the laser beam on the discs forming hot spot by object lens, thereby is recorded in information on the disc or reads information on disc.The big young pathbreaker of focal beam spot determines the optical disc data recording density, thus but the recording capacity of decision CD.Hot spot is more little, and the recording capacity of CD is high more.Usually, the size of focal beam spot (S) is directly proportional with the wavelength (λ) of laser beam, is inversely proportional to the numerical aperture (NA) of object lens.Can release thus, form a small-sized hot spot that is applicable to high-density recording media, must reduce the operation wavelength (λ) of laser beam or increase the numerical aperture (NA) of object lens.Therefore, in the evolution process of CD specification, operation wavelength that it adopted (λ) and numerical aperture (NA) also constantly change.The operation wavelength that initial CD specification is adopted is about 780nm, and the numerical aperture of object lens is 0.45; And the operation wavelength that the DVD specification is adopted has been kept to 650nm, and the numerical aperture of object lens increases to 0.6; Short wavelength's blue light that the HD-DVD of a new generation specification has adopted wavelength to be about 405nm replaces CD, DVD ruddiness, and the numerical aperture of object lens is more than 0.6, to reach as high as 0.85.Since the optical parametric difference that each specification adopted, record/read the information of different discs specification, and the demand which kind of specification optical element just need reach this specification is read/writes down in its requirement.

The different discs specification is except that above-mentioned difference, and the thickness of its CD is also different.Because disc tilt can produce coma, and the thickness of the size of coma and CD has much relations, the coma of the thick more generation of CD is big more.In order to control the coma of CD, the thickness of CD reduces gradually, by the 1.2mm of CD thick reduce to HD-DVD less than 0.6mm.

But high density recording/transcriber needs outside the disc of recoding/reproduction record specification corresponding with it, also needs compatible already present low-density record specification.With the HD-DVD data recording/reproducing device is example, but it needs also to need compatible CD and the DVD CD specification that still accounts at present than big market outside the recoding/reproduction HD-DVD CD specification.Therefore, be used to be applicable to that the optical read/write system of HD-DVD data recording/reproducing device need have the optical system that satisfies three kinds of CD specifications.Yet, have not square one of required numerical aperture difference of above-mentioned operation wavelength difference, object lens and disc thickness between these specifications.So, during this optical read/write system log (SYSLOG)/information reproduction, the optical parametric that need provide the CD specification that adopted with it to be complementary.

Can be in the optical read/write system of the multiple CD specification of above-mentioned compatibility with regard to each specification arrangement one optical system, and its optical parametric mates fully with corresponding CD specification respectively.In above-mentioned HD-DVD optical read/write system, co-exist in three optical systems with difference corresponding HD-DVD specification, DVD specification and CD specification.Each optical system is all a complete light path, has corresponding light source, light receiving element and a plurality of optic path element.Yet the required number of optical elements of this design proposal is more, and this can directly cause this optical read/write system cost height.And number of optical elements is many, and the encapsulation volume of optical read/write system is inevitable very big, deviates from mutually to the miniaturization development with present optic recording/reproducing device.So, existingly in the prior art adopt mode to reduce optical element quantity with the shared part light path of the optical system of corresponding different size, and optic path elements such as common shared collimation lens, object lens.But the optical parametric of optical element is normally by decisions such as shape, materials, and it is fixing unadjustable.Such as collimation lens, it has light-focusing function, but only the divergent beams of the light beam of a certain specific wavelength is changed into parallel beam, and the light beam of other wavelength only can change into approximate parallel beam.Object lens are also like this, it only can converge at its corresponding position well with the parallel beam of specific wavelength of input, and other wavelength is assembled to other position, promptly can there be certain error owing to not matching in this, as spherical aberration, aberration phenomenon in the aberration appear, or the area of focal beam spot is too big, thereby influences the optical property of optical system and the information on the recording/reproducing optical disk correctly.Optical read/write system as above-mentioned HD-DVD data recording/reproducing device, corresponding HD-DVD, DVD and CD specification are provided with light source and optical receiver respectively, and need to be provided with in the optical read/write system that a light path coupling element makes can shared part light path from the light beam of Different Light.Shared collimation lens and object lens only can be at wherein a kind of specification settings, and the HD-DVD specification is set in this way, and then phenomenons such as spherical aberration, aberration will appear in the light path of DVD and CD specification.

[summary of the invention]

Technical matters to be solved by this invention provides a kind of optical read/write system, but three kinds of CD specifications of its recoding/reproduction, and this optical read/write system not only can reduce the encapsulation volume but also the tool favorable optical performance of optical read/write system.

A kind of optical read/write system, but its recoding/reproduction first, the signal of second and third CD specification, and the storage density of CD specification increases progressively successively, this optical read/write system comprises that three produce first respectively, the light source of second and third incident beam, three are oppositely arranged to receive first with light source, the detecting element of second and third incident beam, one collimation lens, one object lens and one have first, second, the prism unit of the 3rd incidence surface and an exiting surface, wherein this first, the wavelength of second and third incident beam is respectively first, the wavelength that second and third CD specification is formulated; This first, second, third incidence surface is oppositely arranged with above-mentioned first, second, third light source respectively, and this first, second and third incident beam enters this prism unit by first, second and third incidence surface respectively, and by same exiting surface output; This prism unit is in the first, the 3rd aspheric surface that incident beam is respectively equipped with in light path, and this collimation lens is arranged in the light path of prism unit exiting surface one side, and has the optical parametric that is complementary with second incident beam; These object lens are over against the optical disc surface setting and have the optical parametric that is complementary with the second CD specification.

Compared with prior art, optical read/write of the present invention system has the following advantages: at first, optical read/write of the present invention system adopts the prism unit of three incidence surfaces of a tool to import from different incidence surfaces from the different wave length light signal of Different Light, and by same exiting surface output, thereby it is different optical is system coupled with shared optical element after prism unit output, thereby reduce the required number of optical elements of optical read/write system of compatible three kinds of CD specifications, and then reduce the encapsulation volume of optical read/write system and reduce the cost of optical read/write system.Moreover, the object lens of the collimation lens of optical read/write of the present invention system and the optical parametric of collimation lens all are complementary with the standard that the second CD specification is formulated, so during the recoding/reproduction second CD specification data, the optical read/write system has the good optical performance.And optical read/write of the present invention system adds an aspherical optical element respectively in the light path of the first, the 3rd incident beam institute warp, the aberration that the deviation of the optical parametric and first of these aspherical optical element recoverable object lens and collimation lens, the 3rd CD specification standard causes, therefore when recoding/reproduction first, the 3rd CD specification data, the optical read/write system also has the good optical performance.

[description of drawings]

Fig. 1 is the synoptic diagram of optical read/write of the present invention system first embodiment.

Fig. 2 is the part light path synoptic diagram of optical read/write system first embodiment.

Fig. 3 A is the mansion view of wavelength-selective mirror of the optical read/write system of Fig. 1.

Fig. 3 B is the light path synoptic diagram of the wavelength-selective mirror of Fig. 3 A.

Fig. 4 is the synoptic diagram of optical read/write of the present invention system second embodiment.

Fig. 5 is the synoptic diagram of optical read/write of the present invention system the 3rd embodiment.

Fig. 6 is the light path synoptic diagram of Pechan prism shown in Figure 5.

[embodiment]

See also Fig. 1, optical read/write of the present invention system 100 is applicable in the high density recording/transcriber of three kinds of CD specifications of recoding/reproduction, but present embodiment is an example with the optical read/write system 100 of recoding/reproduction HD-DVD, DVD and CD specification.This optical read/write system 100 comprises three light source 1a, 1b, 1c, three detecting element 2a, 2b, 2c, three holographic eyeglass 3a, 3b, 3c, a prism unit 4, a pentagonal prism 5, collimation lens 6, catoptron 7, a wavelength-selective mirror 8 and object lens 9, and by semiconductor technology with light source 1a, 1b, 1c, detecting element 2a, 2b, 2c, holographic eyeglass 3a, 3b, 3c, prism unit 4 encapsulation.Light source 1a, 1b, 1c be arranged in parallel and are positioned at same plane, and light source 1a is at the setting of CD specification, and operation wavelength is 780nm; Light source 1b is at the setting of HD-DVD specification, and operation wavelength is 405nm; Light source 1c is at the setting of DVD specification, and operation wavelength is 650nm.Three detecting element 2a, 2b, 2c respectively with three light source 1a, 1b, 1c adjacent and and shape arrange to receive CD, HD-DVD and DVD specification light signal respectively.Each holographic eyeglass 3a, 3b, 3c are oppositely arranged with light signal that light source 1a, 1b, 1c are sent or with the light signal of light path with a pair of light source 1a, 1b, 1c and detecting element 2a, 2b, 2c respectively and reflect on detecting element 2a, 2b, 2c.

See also Fig. 2, this prism unit 4 is between holographic eyeglass 3a, 3b, 3c and pentagon prism 5, it comprises first, second, third prism 41,42,43, and wherein first prism 41 is a rectangular prism, and it has incidence surface 410 and the exiting surface 412 that is oppositely arranged.This incidence surface 410 is first incidence surface of prism unit 4, and it with transmission CD specification light signal, and be that non-spherical structure is to assemble the light signal of importing over against holographic eyeglass 3a.This non-spherical structure except that above-mentioned be located on the incidence surface 410, also can be located on the exiting surface 412.Second, third prism 42,43 is all composite prism, comprises a right-angle prism 420,430 and a parallelogram prism 422,432 respectively.The right-angle prism 420 of this second prism 42 has incidence surface 4200 and with this a right angle relative exiting surface 4202 adjacent with its right angle, this incidence surface 4200, its over against holographic eyeglass 3b with transmission HD-DVD specification light signal.The parallelogram prism 422 of second prism 42 has the incidence surface 4220 and exiting surface 4222 that is oppositely arranged, and two reflectings surface 4224,4226, and 4226 of incidence surface 4220 and reflectings surface are miter angle.Incidence surface 4220 is the 3rd incidence surfaces of prism unit 4, and wherein, this incidence surface 4220 is the 3rd incidence surfaces of prism unit 4, and it is provided with and be that non-spherical structure is to transmit DVD specification light signal over against holographic eyeglass 3c.Reflecting surface 4224 is oppositely arranged with the exiting surface 4202 of right-angle prism 420, and is coated with a rete in its surface (indicating), and this rete is to the 650nm light signal reflection of incident, and to the 405nm light signal along its former transmission direction transmission.

The right-angle prism 430 of prism have an incidence surface 4300 and one and incidence surface 4300 be the reflecting surface 4324 of miter angle, wherein the exiting surface 4222 of the parallelogram prism 422 of this incidence surface 4300 and second prism 42 is oppositely arranged.The parallelogram prism 432 of prism 43 has the incidence surface 4320 and exiting surface 4322 that opposing parallel is provided with, and two reflectings surface 4324,4326 that link to each other with incidence surface 4320 and exiting surface 4322 respectively.The exiting surface 412 opposing parallel settings of the incidence surface 4320 and first prism 41.Reflecting surface 4324 is oppositely arranged with the exiting surface 4322 of right-angle prism 430, and be coated with one second rete (indicating) in its surface, this second rete can be to the reflection of the 780nm light signal of incident, to the 405nm of incident and 650nm light signal along its former transmission direction transmission.Exiting surface 4322 is outgoing end faces of prism unit 4, and 780nm, 650nm and the 405nm light signal from the input of first, second and third plane of incidence exports pentagonal prism 5 to by this outgoing end face respectively.

Pentagonal prism 5 is a pentagon column structure, and it has adjacent vertically disposed incidence surface 50 and exiting surface 51, two reflectings surface 52,53 and a joint face 54.Wherein, remove incidence surface 50 and 51 angles of exiting surface and be 90 and be outside one's consideration, it is 112.5 in four angles and spends.Incidence surface 50 is oppositely arranged with the outgoing end face 4322 of prism unit 4, and two reflectings surface 52,53 link to each other with incidence surface 50, exiting surface 51 respectively and are coated with a total reflection film respectively.This total reflection film is all total reflection to 405nm, 650nm and the 780nm wavelength light signal of incident.

Collimation lens 6 is provided with over against the exiting surface 51 of pentagonal prism 5, and it has the optical parametric that is complementary with the HD-DVD specification.Face catoptron 7 is to be obliquely installed, and itself and horizontal direction tool 45 degree angles transfer transmission vertically to the light signal with horizontal transport.Object lens 9 are over against the optical disc surface setting, and its optical parametric and position are that the disc thickness of the wavelength, numerical aperture and the HD-DVD that are adopted at the HD-DVD specification is set.

Please consult Fig. 3 A and Fig. 3 B simultaneously, wavelength-selective mirror 8 is located at object lens 9 one sides to select the light signal by directive object lens 9.These wavelength-selective mirror 8 centers have a circular first area 81, have an annular second area 82 around this first area 81, and these annular second area 82 outsides are one the 3rd zone 83.Wherein, first part 81 can be passed through 405nm, 650nm and 780nm wavelength light signal; Second area 82 can pass through 405nm, 650nm wavelength light signal, and stops 780nm wavelength light signal; 405nm wavelength light signal only can be passed through in the 3rd zone 82, and stops 650nm and 780nm wavelength light signal.Thereby, numerical aperture and HD-DVD, DVD, the CD specification of the actual employing of object lens 9 are complementary.

When writing down or reading the CD specification data, light source 1a sends the light signal of 780nm wavelength to form first incident beam, and this first incident beam is entered first prism 41 of prism unit 4 by first incidence surface 410 of prism unit 4 behind holographic eyeglass 3a.Because this first incidence surface 410 is a non-spherical structure, its first incident beam to input has light-focusing function.This first incident beam was exported by the exiting surface 412 of first prism 41 behind the optically focused through the first time of first incidence surface 410.Because the incidence surface 4320 of the exiting surface 412 of first prism 41 and the parallelogram prism 432 of prism 43 is oppositely arranged, so enter the parallelogram prism 432 of prism 43 via incidence surface 4320 from first incident beam of exiting surface 412 outputs.First incident beam that enters parallelogram prism 432 is reflected face 4326 reflections earlier to change its transmission direction, first incident beam after the reflection is incident to another reflecting surface 4324, owing to be plated on the 780nm wavelength light signal tool reflection function of rete on this reflecting surface 4324 to importing, so so that the transmission direction of first incident beam is reduced to its direction before entering prism 43, and it is via outgoing end face 4322 outputs of prism unit 4 by secondary reflection again for this first incident beam.

Enter in the pentaprism 5 from first incident beam of prism unit 4 output incidence surface 50 via pentagonal prism 5, and behind reflecting surface 52,53 secondary reflections by exiting surface 51 outputs.From first incident beam of pentagonal prism 5 output through collimation lens 6 after by the second time optically focused to form a nearly parallel beam.This nearly parallel beam is after 7 reflections of face catoptron, and its transmission direction transfers transmission vertically to by the along continuous straight runs transmission, and inputs to wavelength-selective mirror 8.Can pass through 780nm wavelength light signal because wavelength-selective mirror 8 only is positioned at the first area of center, thereby the light signal of the first incident beam outside is stopped that by wavelength-selective mirror 8 its inboard light signal is incident to object lens 9 after seeing through this first area.Object lens 9 are assembled the nearly parallel beam of 780nm wavelength of input to the data record layer of CD disc, and are reflected to form one first Returning beam by this recording layer.This first Returning beam is back to holographic eyeglass 3a along first incident beam through light path.Holographic eyeglass 3a is to first Returning beam refraction output of input, so that this light beam falls within on the detecting element 2a, detecting element 2a changes into electric signal output with this first Returning beam.

When writing down or reading the HD-DVD specification data, light source 1b sends the light signal of 405nm wavelength to form one second incident beam.This second incident beam is entered the right-angle prism 420 of prism unit 4 by second incidence surface 4200 of prism unit 4 behind holographic eyeglass 3b.When this second incident beam is exported from the exiting surface 4202 of right-angle prism 420, through the reflecting surface 4224 of parallelogram prism 422.The light signal tool transmission function of the 405nm wavelength of 4224 pairs of inputs of reflecting surface is after so this second incident beam passes this reflecting surface 4202 along its former transmission direction, by exiting surface 4222 outputs.Enter this prism 43 from second incident beam of second prism 42 output by the incidence surface 4300 of the right-angle prism 430 of prism 43.Second incident beam passes right-angle prism 430 and inputs to the reflecting surface 4324 of parallelogram prism 432.The 405nm of 4324 pairs of inputs of this reflecting surface and the light signal transmission of 650nm wavelength so this second incident beam can reach exiting surface 4322 along its former transmission direction, and export pentagonal prism 5 to from exiting surface 4322.This second incident beam is identical with the corresponding transmission path of recoding/reproduction CD specification to the transmission path that exports wavelength-selective mirror 8 in input pentagonal prism 5, explanation no longer in detail herein.This second incident beam inputs to wavelength-selective mirror 8 after above-mentioned transmission, because 405nm wavelength light signal all can be passed through in first, second, third zone of this wavelength-selective mirror 8, so the 3rd incident beam can input to object lens 9 fully, and assembles to HD-DVD optical disc data layer by object lens 9.This data Layer reflects to form second Returning beam second incident beam of incident.The input path of returning the light path and second incident beam of this second Returning beam is basic identical, and its difference is that this second Returning beam is refracted when inputing to holographic eyeglass 3b and falls within on the detecting element 2b.Detecting element 2b produces electric signal output according to second Returning beam that receives.

When record or when reading the DVD specification data, the light signal that light source 1c sends the 650nm wavelength to be forming one the 3rd incident beam, and the 3rd incident beam enters second prism 42 by the 3rd incidence surface 4220 of prism unit 4 behind holographic eyeglass 3c.Because the 3rd incidence surface 4220 is aspheric surfaces, it is to the light beam tool light-focusing function of input, so the 3rd incident beam is via the 3rd incidence surface 4220 convergent beams.The 3rd incident beam from reflecting surface 4226 total reflections of the parallelogram prism 422 of second prism 42 to transfer to reflecting surface 4224.The 650nm wavelength light signal tool reflection function of 4224 pairs of incidents of reflecting surface, so the 3rd incident beam face 4224 that is reflected reflexes to exiting surface 4222, and export prism 43 to via exiting surface 4222.The 3rd incident beam is identical to the respective optical path of second incident beam institute warp that inputs to transmission path between the wavelength-selective mirror 8 and record/read HD-DVD specification in entering prism, please, no longer repeat referring to the light path explanation of described second incident beam of last joint herein.The regional transmission 650nm of first, second of wavelength-selective mirror 8 wavelength light signal, the 3rd region blocks 650nm wavelength light signal, so the 3rd incident beam in first, second zone of the wavelength-selective mirror 8 of input can see through wavelength-selective mirror 8 and input to object lens 9, and converges at DVD optical disc data layer by object lens 9.This data Layer reflects to form the 3rd Returning beam the 3rd incident beam of incident, the transmission path of the transmission path of the 3rd Returning beam and the 3rd incident beam is basic identical, and its difference is that the 3rd Returning beam is refracted when inputing to holographic eyeglass 3c and falls within on the detecting element 2c.Detecting element 2c produces an electric signal according to the 3rd Returning beam, and exports this electric signal.

From the above, the parameter that the collimation lens 6 of optical read/write system 100 and the optical parametric of object lens 9 and HD-DVD specification are formulated fits like a glove, so the HD-DVD specification record/when reading, optical read/write system 100 can not produce phenomenons such as aberration, thereby has the good optical performance.Optical read/write system 100 is during for the data recording/reproducing of DVD, CD specification, though collimation lens 6 and object lens 9 not exclusively mate with its standard, increase an aspheric correcting lens face 4220,410 in right its transmission light path, so that the aberration that produces is proofreaied and correct respectively at DVD, CD.And, being provided with wavelength-selective mirror 8 in the transmission light path before the object lens 9, it has different transmission range for the different wave length light signal, eliminates the excessive influence to DVD, CD specification light signal of numerical aperture of object lens 9 with this.Therefore, for HD-DVD, DVD and CD specification, optical read/write system 100 all has the good optical performance.

Secondly, the prism unit 4 of this optical read/write system 100 has first, second, third incidence surface 410,4200,4220 and an outgoing end face 4322.The light signal that can import from different light paths by first, second, third incidence surface 410,4200,4220, and through after the internal transmission of prism unit 4, by same outgoing end face 4322 outputs.Thereby, realize that a plurality of transmission light path couplings are to make full use of optical element.Moreover, pentagonal prism 5 can reflect between its surface, thereby can change the transmission direction of light path, under the condition that does not reduce optical path length, reduce the shared physical size of optical system with this, and can make full use of the shared space of optical read/write system 100, it is long and can not reduce to be subject to single direction with the encapsulation volume of avoiding optical read/write system 100.

See also Fig. 4, it is second embodiment of optical read/write of the present invention system, this optical read/write system 100 ' basic identical with the optical read/write system 100 of above-mentioned embodiment.Only, the collimation lens 6 of optical read/write system 100 ' omission optical read/write system 100, but optical read/write system 100 ' in be provided with a pentagonal prism 5 ', the pentagonal prism 5 of itself and optical read/write system 100 is basic identical, the two difference be pentagonal prism 5 ' exiting surface be a non-spherical structure.Thereby, this pentagonal prism 5 ' except that function, also have light-focusing function to replace collimation lens 6 with pentagonal prism 5.

See also Fig. 5, it is the 3rd embodiment of optical read/write of the present invention system, this optical read/write system 100 " and the light path design of the optical read/write system 100 of first embodiment is also basic identical, and the two difference is that optical read/write system 100 " employing one Pechan prism 5 " replaces the pentagonal prism 5 of optical read/write system 100.Please consult Fig. 6 simultaneously, Pechan prism 5 " be a composite prism, comprise first, second partly 51 ", 52 " of being oppositely arranged, wherein this first, second partly 51 ", 52 " have an identical material.This first 51 " comprises an incidence surface 510 ", with this incidence surface 510 " two adjacent reflectings surface 511 ", 512 ".Two reflectings surface 511 ", 512 " are coated with a total reflection film respectively.This total reflection film is all total reflection to 405nm, 650nm and the 780nm wavelength light signal of incident.This second portion 52 " comprises an exiting surface 520 " and two reflectings surface 521 ", 522 ".Incidence surface 510 " with exiting surface 520 " be arranged in parallel, and " reflecting surface 511 first partly 51 " with second partly 52 " combine; and the part is coated with reflectance coating respectively; thus this reflecting surface 511 " so that the light beam that is incident in coating film area is had reflection function, is incident in plating reflectance coating light beam in addition and has transmission function.The basic parameter of described composite prism 5 is: a=4mm, b=4.828mm, =45 degree, θ=112.5 degree, β=67.5 degree.

Incident beam is by Pechan prism 5 " incidence surface 510 " input, and transfers to reflecting surface 511 " coating film area, thereby reflexed to reflecting surface 512 by it ".The not coating film area of reflecting surface 512 " to the beam reflection of incident, so that it falls within reflecting surface 511 ", and export Pechan prism 5 " second partly 52 " thus to.From the first not coating film area of 51 " incident beam of output is via reflectings surface 521 " enter second partly 52 " exiting surface 520 " total reflection to the reflecting surface 522 total reflection plated film district of "; reflex to 521 again " partly, thereby quilt is reflected back exiting surface 520 once more ", and " the output via exiting surface 520.

Claims

1. optical read/write system, but its recoding/reproduction first, the signal of second and third CD specification, and the storage density of CD specification increases progressively successively, this optical read/write system comprises that three produce first respectively, the light source of second and third incident beam, three corresponding with light source to receive first, the detecting element of second and third incident beam, the light signal of three light signals that light source can be sent or light path reflects the holographic eyeglass on detecting element, one collimation lens and object lens, wherein this first, the wavelength of second and third incident beam is respectively first, the wavelength that second and third CD specification is formulated; It is characterized in that: this optical read/write system comprises that also one has the prism unit of first, second, third incidence surface and an exiting surface, an and wavelength-selective mirror, this first, second, third incidence surface is oppositely arranged with above-mentioned first, second, third light source respectively, this first, second and third incident beam enters this prism unit by first, second and third incidence surface respectively, and by same exiting surface output; This prism unit is in the first, the 3rd aspheric surface that incident beam is respectively equipped with in light path, and this collimation lens is arranged in the light path of prism unit exiting surface one side, and has the optical parametric that is complementary with second incident beam; This wavelength-selective mirror is located at the side that object lens deviate from optical disc surface, and be provided with first, second, third zone from inside to outside successively, wherein this first area is to all transmissions of first, second, third incident beam of incident, this second area stops first incident beam of incident and to second, third incident beam transmission, and the 3rd zone stops the first, the 3rd incident beam of incident and to the second incident beam transmission; These object lens are over against the optical disc surface setting and have the optical parametric that is complementary with the second CD specification.

2. as the described optical read/write of 1 of claim the system, it is characterized in that: this prism unit has first, second, third prism, this first, second prism is positioned at prism one side and parallel mutually the setting, this first prism has incidence surface and the exiting surface that is oppositely arranged, and this incidence surface is non-spherical structure and is first incidence surface of this prism unit, and this first incident beam is imported first prism and exported prism to via this exiting surface from incidence surface.

3. as the described optical read/write of 2 of claims the system, it is characterized in that: this second prism is a composite prism, it comprises a right-angle prism and parallelogram prism, wherein the hypotenuse of this right-angle prism combines with a wherein hypotenuse of this parallelogram prism, and this a right-angle prism wherein right-angle side is second incidence surface of this prism unit.

4. as the described optical read/write of 3 of claims the system, it is characterized in that: this parallelogram prism comprises parallel relative incidence surface and exiting surface and two parallel relative reflectings surface, and this incidence surface is non-spherical structure and is the 3rd incidence surface of this prism unit.

5. as the described optical read/write of 4 of claims the system, it is characterized in that: on this parallelogram prism and the reflecting surface that this right-angle prism combines a coating is arranged, this coating to second incident beam of input along its former transmission direction transmission and to the 3rd incident beam reflection of input.

6. as the described optical read/write of 2 of claims the system, it is characterized in that: this prism is a composite prism, it comprises a right-angle prism and parallelogram prism, wherein the hypotenuse of this right-angle prism combines with a wherein hypotenuse of this parallelogram prism, this first prism is oppositely arranged with a end away from this parallelogram prism of this right-angle prism, and this second prism and this right-angle prism are oppositely arranged.

7. as the described optical read/write of 6 of claims the system, it is characterized in that: this parallelogram prism has parallel relative incidence surface, exiting surface and two parallel relative reflectings surface, wherein this parallelogram prism is provided with first incident beam reflection of a pair of incident in the reflecting surface that combines with right-angle prism, and to second, third incident beam of input coating along its former transmission direction transmission.

8. as the described optical read/write of 7 of claims the system, it is characterized in that: the exiting surface of this parallelogram prism is the exiting surface of this prism unit, and first, second, third incident beam is all by this exiting surface output.

9. as the described optical read/write of 1 of claim the system, it is characterized in that: this optical read/write system also comprises a pentagonal prism, it is positioned on the light path between this prism unit and collimation lens, this pentagonal prism has an incidence surface, an exiting surface and at least two reflectings surface, angle is 90 degree between incidence surface and exiting surface, all the other of pentagonal prism four angles are all 112.5 degree, and at least two reflectings surface of this pentagonal prism are coated with total reflection film respectively.