JPH05120726A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide the optical information recording and reproducing device which can stably detect a spot position error and information signals with a smaller number of parts and high light utilization efficiency. CONSTITUTION:This device has a laser diode 1, a collimating lens 2 and an objective lens 4 and has a beam splitter 3 for separating going light and medium reflected light. The device consists of a lambda/2 plate 6 disposed by aligning its optical axis to the separated return light 11 reflected from the medium, an optical path splitter 7, a convergent lens 8, a Wollaston prism 9, and a photodetector 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information by light.

[0002]

2. Description of the Related Art FIG. 19 is a block diagram of a conventional optical information recording / reproducing apparatus.

In the figure, a laser diode (1)
And a collimating lens (2) for collimating the divergent light emitted from the laser diode, the light transmitted through the collimating lens (2) and directed to the information recording medium (5) and the information recording medium (5). Has two beam splitters (14) and (15) for separating the reflected return light from
The objective lens (4) for converging the light transmitted through the two beam splitters (14) and (15) on the surface of the information recording medium (5), and the objective lens (4) which is reflected by the information recording medium (5) A converging lens (16) for converging the return light that has been transmitted through 4) and separated by the beam splitter (15);
The light beams converged by the converging lens (16) are orthogonal to each other 2
Recording information signal including a Wollaston prism (17) for separating into two polarization components, and a two-split photodetector (18) for independently detecting two light beams separated by the Wollaston prism (17) The detection system, the beam splitter (14) for separating the reflected return light from the information recording medium (5) that has passed through the beam splitter (15), and the return light separated by the beam splitter (14) Converging lens for converging (19)
And a beam splitter (20) for separating the light beam converged by the converging lens (19) into light for focus error detection and light for track error detection, and two-split light detection for track pushle signal detection. Information detection system and spot position error detection, which is a spot position error detection system including a detector (21), a knife edge (22) for focus error detection by the knife edge method, and a two-divided photodetector (23). The system had an independent structure.

[0004]

In the above-mentioned conventional optical information recording / reproducing apparatus, since the recording information signal detection system and the spot position error detection system are independent from each other, the number of parts is large, and therefore adjustment is difficult. In addition, there is a problem that it is difficult to miniaturize, and since it is necessary to divide the light amount by two beam splitters in the detection system, it is attempted to increase the emission efficiency from the laser diode to the information recording medium. There is a problem that the amount of light returning to the detection system side becomes insufficient, and if an attempt is made to obtain a sufficient amount of light returning to the detection system side, the emission efficiency will decrease.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an optical information recording / reproducing apparatus having a high light utilization efficiency in which the components of the recording information detecting system and the spot position error detecting system are reduced. It is intended.

[0006]

An optical information recording / reproducing apparatus according to a first aspect of the present invention includes a laser diode, a collimating lens for collimating divergent light emitted from the laser diode, and the laser. A beam splitter for separating the light directed from the diode toward the information recording medium and the reflected return light from the information recording medium, and the light emitted from the laser diode and transmitted through the beam splitter is transmitted onto the surface of the information recording medium. An objective lens for converging and an optical axis of the reflected return light which is transmitted from the information recording medium through the objective lens and is separated and reflected by the beam splitter are located in a plane φ perpendicular to the z axis with the optical axis as the z axis. With the intersection of the ball shape pattern of the reflected return light and the z-axis being the origin, it is orthogonal to the track of the information recording medium, which is the direction of the ± first-order diffracted light. Λ / 2 wave plate which is provided on the z axis and rotates the polarization plane by taking the x axis in a direction perpendicular to the x axis and the y axis in the direction orthogonal to the x axis in the plane φ, and a ball in the xy plane. Corresponding to the shape pattern, at least two divided areas are provided symmetrically with respect to the origin in the y-axis direction so as to eliminate the components of the 1st-order diffracted light, and 1 with respect to the origin in the x-axis direction.
An optical path splitter that has at least two split regions that are provided so as to capture the components of the next-order diffracted light, separates the light flux, a converging lens that converges the light flux from the optical path splitter, and a light flux that is converged by the converging lens is polarized. It is provided with a Wollaston prism for separating into components and a photodetector for detecting and converting each light beam separated by the Wollaston prism.

An optical information recording / reproducing apparatus according to a second aspect of the present invention is the optical information recording / reproducing apparatus according to the first aspect of the invention, which corresponds to the ball shape pattern in the xy plane of the optical path splitter. Of at least two divided areas provided so as to eliminate the component of the first-order diffracted light symmetrically with respect to the origin in the y-axis direction, one on the positive side in the y-axis direction is an area A, and one on the negative side is an area C, Of the at least two divided areas provided so as to take in the component of the first-order diffracted light symmetrically with respect to the origin in the x-axis direction, one on the positive side in the x-axis direction is the area B, and one on the negative side is
Regions A, B, C and D each have an optical path splitter having an independent emission angle.

An optical information recording / reproducing apparatus according to a third aspect of the present invention is the optical information recording / reproducing apparatus according to the second aspect, wherein the photodetector is composed of 10 photodetector sections, and the optical path is divided. When the respective components of the ball shape pattern of the reflected return light of the information recording medium divided by the regions A, B, C, D of the container are defined as the reflected return light components A, B, C, D corresponding to the divided regions. at least four components of the reflected return light, the converging lens, with respect to the output-side prism of the Wollaston prism by the Wollaston prism, the ordinary ray index o, the extraordinary ray shows with the subscript e a _o , B _o , C _o , D _o , A _e , B _e ,
At least eight luminous fluxes of C _e and D _e are separated, and A _o ,
The C _o is arranged on the dividing line of each of the two divided light detector, B
_o , D _o , A _e , B _e , C _e , and D _e are detected independently, or A _e and C _e are respectively arranged on the dividing lines of the two-division photodetector, and A _o , B _o , C _o , D _o , _Be , _De
The photodetector is arranged so as to detect each independently.

An optical information recording / reproducing apparatus according to a fourth aspect of the present invention is the optical information recording / reproducing apparatus according to the third aspect of the invention, in which the light beam A _o is detected by the two-split photodetectors a and d, and the light beam C is detected. _o is detected by the two-split photodetectors b and c, the luminous flux B _o is the photodetector f, the luminous flux D _o is the photodetector e, the luminous flux A _e is the photodetector h, the luminous flux C _e is the photodetector i, light beam B _e photodetection unit j, the light beam D _e detected by the light detecting portion g, the light detection unit a, b, c,
The outputs of d, e, f, g, h, i and j are respectively V
(A), V (b), V (c), V (d), V (e), V
When (f), V (g), V (h), V (i), and V (j) are used, the focus error signal is {V (a) + V (c)}.
A means for detecting by − {V (b) + V (d)} is provided.

An optical information recording / reproducing apparatus according to a fifth aspect of the present invention is the optical information recording / reproducing apparatus according to the fourth aspect, wherein a track error signal is {V (e) -V (f)}.
It is equipped with a means for detecting.

An optical information recording / reproducing apparatus according to a sixth aspect of the present invention is the optical information recording / reproducing apparatus according to the fourth aspect, wherein a track error signal is {V (e) + V (g)}-{V ( f) + V (j)} is provided.

The optical information recording / reproducing apparatus of the seventh invention of the present invention is the optical information recording / reproducing apparatus of the fourth invention, wherein the fluctuation signal of the light quantity is V (a) + V (b) + V (c) + V. (D) + V (e) + V (f) + V (g) + V (h) + V (i) + V (j) is provided, and the fluctuation signal of the polarization plane is V (a) + V (b) + V. (C) + V (d) + V (e) + V (f)-{V (g) + V (h) + V (i) + V (j)} is provided.

An optical information recording / reproducing apparatus according to an eighth aspect of the present invention is the optical information recording / reproducing apparatus according to the fourth aspect of the invention, wherein the fluctuation signal of the polarization plane is V (a) + V (b) + V (c). A means for detecting with + V (d)-{V (h) + V (j)} is provided.

[0014]

According to the above construction, the reflected return light from the information recording medium reflected and separated by the beam splitter is converted into light beams A, B, C, which correspond to the ball shape pattern by the λ / 2 wavelength plate and the optical path splitter. Divided into four parts, D, A, B,
The light beam divided into four parts C and D is further converged by a converging lens, and the normal signal components A _o , B _o ,
C _o, D _o error component A _e, since B _e, C _e, and separated into 8 split light flux D _e detected operation by the light detector outputs an error signal, the optical information signal detection and error signal Can be processed by one line, and finer correction data of the optical information signal can be obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a basic configuration diagram of an optical information recording / reproducing apparatus according to a first embodiment of the present invention.

The divergent light emitted from the laser diode (1) is collimated by the collimator lens (2) and is focused on the information recording medium (5) surface by the objective lens (4) through the beam splitter (3). Information recording medium (5)
The medium-reflected return light (11) is separated from the light going from the beam splitter (3) via the objective lens (4).

The medium reflected return light (11) obtained via the beam splitter (3) is a λ / 2 wave plate (6) and an optical path splitter (7) arranged so as to coincide with the optical axis of the reflected return light. ，
It is detected as an electric signal by the photodetector (10) through the converging lens (8) and the Wollaston prism (9).

Here, the track pitch of the guide groove of the optical information recording medium (5) used thereafter is P μm, the wavelength of the light used for recording and reproducing information is λ nm, the numerical aperture of the objective lens (4) is NA, and the incident light is NA. Let the radius of the pupil be amm.

FIG. 2 shows the relationship between P, λ and NA in the optical information recording / reproducing apparatus according to the first embodiment of the present invention (NA · P
FIG. 6 is a diagram showing a ball shape pattern of the medium-reflected return light in the case of −λ)> 0, and how to take xy axes with respect to this pattern.

FIG. 3 is a diagram showing an example of an optical path splitter according to the second embodiment of the present invention. This optical path splitter (7)
Is the medium return light ball shape pattern seen in the plane φ shown in FIG. 2 as follows: 1) Interfering light between + 1st order diffracted light and 0th order diffracted light (B) 2) Interfering light between −1st order diffracted light and 0th order diffracted light (D) 3) Other light (A), (C) is an optical path divider having a function of dividing into four regions and giving independent emission angles, and the divided region A has a shape as shown in FIG. It is needless to say that the present invention is also carried out by a prism formed of a plastic mold or the like in which each divided region has an inclination angle different from each other, B, C, D, or a hologram element having the pattern shown in FIG. ..

FIG. 4 is a mutual layout diagram of the division area and the return light ball shape pattern of the optical path divider of the present invention. 4A and 4B show the mutual arrangement of the division area of the optical path divider shown in FIG. 3 and the return light ball shape pattern shown in FIG. 2.

Similarly, in FIGS. 5 to 7 and 8 to 10, (NA
Another embodiment of the divided region of the optical path divider when P-λ)> 0 is shown. In these cases, there are five straight lines and two straight lines, as shown in FIGS. 6 and 9, divided areas A, B, and B of the divider (7).
This is an example in which C and D are linearly divided. As a result, as shown in FIG. 7 and FIG.
Even if D comes in, the wrap-around of the track error signal with respect to the focus error detection signal, which will be described later, only increases. Therefore, it is needless to say that a similar effect can be obtained if a slight characteristic deterioration is allowed. Simplifies the creation of. Note that FIGS. 5 and 8 show the ball shape pattern, FIGS. 6 and 9 show the division area pattern of the optical path divider, and FIGS.
0 shows the mutual arrangement with the optical path splitter for the ball shape pattern.

Similarly, FIGS. 11 to 13 and FIGS. 14 to 16 show another embodiment of the optical path splitter in the case of (NA · P−λ) ≧ 0.

The medium-reflected return light (11) separated by the beam splitter (3) has its plane of polarization rotated by about 45 degrees by the λ / 2 plate (6), and the four areas A of the optical path splitter (7). , B, C, D are separated into four light beams.

Next, a third embodiment of the present invention will be described.

The above four light beams are shown in FIGS. 3, 6, 9, 12, and 1.
The luminous fluxes A, B, C, and D are named in correspondence with the four areas shown in FIG.

FIG. 17 shows a third embodiment 10 of the present invention.
It is a block diagram of a split photodetector. In the figure, a luminous flux A ₀ is a two-division photodetection section a, d, and a luminous flux C ₀ is a two-division photodetection section b,
c, the light beam B ₀ is the light detection unit f, the light beam D ₀ is the light detection unit e, and similarly, A _e is h, C _e is i, _Be is j, and D _e is g.

FIG. 18 is a diagram showing the polarization bundle of the Wollaston prism according to the third embodiment of the present invention and the convergence position on the photodetector.

The above four light fluxes A, B, C, D are converted into four convergent light fluxes by the converging lens (8), and the polarization components are separated into two orthogonal polarization components by the Wollaston prism (9). , 8 convergent light fluxes A ₀ , A _e ,
_{B 0, B e, C 0} , C e, is separated into D _0, D _e. Note that A ₀ , B ₀ , C ₀ , D ₀ are normal components A _e , _Be ,
C _e and D _e represent error components.

The above eight luminous fluxes are projected onto a 10-division photodetector shown in FIG. 17, which is an embodiment of the photodetector (10).
It converges as shown in 8.

Next, in the fourth embodiment, the outputs of the photodetectors a to j shown in FIG. 17 are respectively set to V (a) to V (V).
Assuming that (j), the focus error is {V (a) + V
(C)}-{V (b) + V (d)}, which is detected by the comparison judgment of the two-division photodetector.

Next, in the fifth and sixth embodiments of the present invention, the track error is detected as {V (e) -V (f)} as a deviation in the x-axis direction, or {V (e ) + V
(G)}-{V (f) + V (j)}.

Next, as a seventh embodiment of the present invention, a preformatted signal, a light quantity fluctuation signal of a hole-type optical information recording medium, a phase change medium or the like is V (a) + V (b) + V (c) + V. The signal total of (d) + V (e) + V (f) + V (g) + V (h) + V (i) + V (j) is detected.

The fluctuation signal of the plane of polarization of the magneto-optical disk is V (a) + V (b) + V (c) + V (d) + V (e) + V (f)-{V (g) + V (h) + V (i ) + V (j)}.

Next, as an eighth embodiment of the present invention, detection is performed by V (a) + V (b) + V (c) + V (d)-{V (h) + V (j)}.

In this way, the optical information signal and the spot position error signal are processed in one line, and fine signal correction can be performed by the output data of each error signal detected and calculated.

[0038]

As described above, according to the present invention, the spot position error detection system and the recording information detection system are composed of only the λ / 2 plate, the optical path splitter, the detection lens, the Wollaston prism, and the photodetector. There is an effect that the number of parts can be significantly reduced.

Further, since the spot position error detection system does not have a light shielding portion such as a knife edge, the light utilization efficiency is extremely high, and thus a large signal amplitude can be obtained.

Further, since the error signal and the information signal are detected by using the same beam by adopting the above-mentioned configuration,
Since the reflectance of the beam splitter can be kept low, and the number of beam splitters has been reduced to one, the distance from the laser diode to the information recording medium via the collimating lens, beam splitter, and objective lens can be reduced. There is an effect that the light utilization efficiency of the optical path can be increased.

Further, when the number of beam splitters in the outgoing optical path is reduced to one, and the light utilization efficiency of the outgoing optical path equivalent to that in the conventional case is sufficient, the reflectance of the beam splitter is increased and an error signal is generated. There is also an effect that both signal amplitudes of the information signal can be made larger.

In addition, since the optical path splitter having the above-described divided areas extracts and uses most of the ± 1st-order diffracted light components as a beam for focus error detection, it is used as a beam for focus error detection. There is an effect that a stable focus error signal with a very small signal wraparound can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical information recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 shows (NA · P-λ) according to the first embodiment of the present invention>
It is a figure showing a ball shape pattern in case of 0, and how to take an xy axis.

FIG. 3 is a diagram showing an example of an optical path splitter according to a second embodiment of the present invention.

FIG. 4 is a mutual arrangement diagram of a division area and a return light ball shape pattern of an optical path divider according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a ball shape pattern when the optical path splitter according to the second embodiment of the present invention is divided into five straight lines.

FIG. 6 is a division area pattern diagram of an optical path divider when dividing into five straight lines according to a second embodiment of the present invention.

FIG. 7 is a mutual layout diagram of an optical path splitter and a ball shape pattern when dividing into five straight lines according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a ball shape pattern when the optical path splitter according to the second embodiment of the present invention is divided into two straight lines.

FIG. 9 is a division area pattern diagram of an optical path divider at the time of dividing into two straight lines according to a second embodiment of the present invention.

FIG. 10 is a mutual layout diagram of an optical path splitter and a ball shape pattern when splitting into two straight lines according to a second embodiment of the present invention.

FIG. 11 shows a second embodiment of the present invention (NA · P-λ).
It is a ball shape pattern figure in the case of ≧ 0.

FIG. 12 shows a second embodiment of the present invention (NA · P−λ).
It is a division | segmentation area pattern figure of an optical path splitter in the case of ≧ 0.

FIG. 13 shows a second embodiment of the present invention (NA · P−λ).
FIG. 9 is a mutual layout diagram of an optical path splitter and a ball shape pattern when ≧ 0.

FIG. 14 shows a second embodiment of the present invention (NA · P-λ).
It is a ball shape pattern figure at the time of dividing | segmenting into two straight lines in the case of> = 0.

FIG. 15 shows a second embodiment of the present invention (NA · P−λ).
It is a division area pattern diagram of an optical path divider by two straight line divisions when ≧ 0.

FIG. 16 shows a second embodiment of the present invention (NA · P−λ).
FIG. 6 is a mutual layout diagram of an optical path splitter and a ball shape pattern when splitting into two straight lines when ≧ 0.

FIG. 17 is a configuration diagram of a 10-division photodetector according to a third embodiment of the present invention.

FIG. 18 is a diagram showing a polarization bundle of a Wollaston prism according to a third embodiment of the present invention and a convergence position on a photodetector.

FIG. 19 is a block diagram of a conventional optical information recording / reproducing apparatus.

[Explanation of symbols]

1 laser diode 2 collimating lens 3 beam splitter 4 objective lens 5 information recording medium 6 λ / 2 wavelength plate 7 optical path splitter 8 converging lens 9 Wollaston prism 10 photodetector A, B, C, D split area a, b, c, d, e, f, g, h, i light detector _{A o, B o, C o} , D o normal component _{A e, B e, C e} , D e error component

Claims (8)

[Claims] 1. A laser diode, a collimator lens for collimating divergent light emitted from the laser diode, and light separating from the laser diode toward the information recording medium and reflected return light from the information recording medium. A beam splitter for moving the light, an objective lens for converging the light emitted from the laser diode and passing through the beam splitter onto the surface of the information recording medium, and the objective lens for passing through the objective lens from the information recording medium. The optical axis of the reflected return light separated and reflected by the beam splitter is z
In the direction orthogonal to the tracks of the information recording medium, which is the direction of the ± 1st-order diffracted light, with the intersection of the ball shape pattern of the reflected return light lying in the plane φ perpendicular to the z-axis as the axis and the z-axis being the origin. A λ / 2 wave plate which is provided on the z axis and rotates the polarization plane, which has an x axis and a y axis in a direction orthogonal to the x axis in the plane φ plane, and a ball shape pattern in the xy plane. Correspondingly, at least two are provided symmetrically with respect to the origin in the y-axis direction so as to eliminate the component of the first-order diffracted light
An optical path splitter having two divided areas and at least two divided areas provided so as to take in a component of the first-order diffracted light symmetrically with respect to the origin in the x-axis direction, and a converging lens for converging the light flux from the optical path splitter. And a Wollaston prism for separating the light beam converged by the converging lens into polarized light components, and a photodetector for detecting and converting the respective light beams separated by the Wollaston prism for output. Optical information recording / reproducing device. 2. The optical information recording / reproducing apparatus according to claim 1, wherein a component of the first-order diffracted light is eliminated symmetrically with respect to the ball shape pattern in the y-axis direction on the origin in the xy plane of the optical path splitter. At least 2 provided to
Of the two divided areas, one on the positive side in the y-axis direction is an area A and the other on the negative side is an area C, and at least two are provided symmetrically with respect to the origin in the x-axis direction so as to take in the component of the first-order diffracted light. When one of the divided areas on the positive side in the x-axis direction is area B and one on the negative side is area D, the areas A, B, C, and D are each composed of an optical path splitter having an independent emission angle. An optical information recording / reproducing apparatus characterized in that 3. The optical information recording / reproducing apparatus according to claim 2, wherein the photodetector is composed of 10 photodetector sections and is divided by areas A, B, C, D of the optical path splitter. When the respective components of the ball shape pattern of the reflected return light of the information recording medium are reflected return light components A, B, C and D corresponding to the divided areas, at least four components of the reflected return light are the converging lens. , by the Wollaston prism, with respect to the output-side prism of the Wollaston prism, the ordinary ray index o, shown with the subscript e the extraordinary ray _{a o, B o, C o} , D o, a e, B _e ,
At least eight luminous fluxes of C _e and D _e are separated, and A _o ,
The C _o is arranged on the dividing line of each of the two divided light detector, B
_o , D _o , A _e , B _e , C _e , and D _e are detected independently, or A _e and C _e are respectively arranged on the dividing lines of the two-division photodetector, and A _o , B _o , C _o , D _o , _Be , _De
An optical information recording / reproducing apparatus, characterized in that a photo-detecting section is arranged so as to detect each independently. 4. The optical information recording / reproducing apparatus according to claim 3, wherein the luminous flux A _o is detected by the two-split photodetectors a and d,
The light flux C _o is detected by the two-split light detection units b and c, the light flux B _o is the light detection unit f, the light flux D _o is the light detection unit e, the light flux A _e is the light detection unit h, and the light flux C _e is the light detection unit. i, the light beam B _e photodetection unit j,
The light beam D _e detected by the light detecting portion g, the light detection unit a, b, c,
The outputs of d, e, f, g, h, i and j are respectively V
(A), V (b), V (c), V (d), V (e), V
When (f), V (g), V (h), V (i), and V (j) are used, the focus error signal is {V (a) + V (c)}.
An optical information recording / reproducing device having means for detecting by − {V (b) + V (d)}. 5. The optical information recording / reproducing apparatus according to claim 4, wherein the track error signal is {V (e) -V.
(F)} An optical information recording / reproducing apparatus having a detecting means. 6. An optical information recording / reproducing apparatus according to claim 4, wherein the track error signal is {V (e) + V (g)}.
An optical information recording / reproducing apparatus having a means for detecting by − {V (f) + V (j)}. 7. The optical information recording / reproducing apparatus according to claim 4, wherein the fluctuation signal of the light quantity is V (a) + V (b) + V (c) + V (d) + V (e) +
V (f) + V (g) + V (h) + V (i) + V (j) is included, and the fluctuation signal of the polarization plane is V (a) + V (b) + V (c) + V (d). + V (e) +
V (f)-{V (g) + V (h) + V (i) + V
(J)} An optical information recording / reproducing apparatus having a means for detecting. 8. The optical information recording / reproducing apparatus according to claim 4, wherein the variation signal of the polarization plane is V (a) + V (b) + V (c) + V (d)-{V (h) + V (j). } An optical information recording / reproducing apparatus having a means for detecting by