JP2001110077A - Optical information recorder-reproducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problem that a position shift is caused between recording and reproducing light spots in the optical axis direction by the shrinkage of an adhesive and the stable recording/reproducing operations can not be performed. SOLUTION: The position of a semiconductor laser 10 for reproducing or a semiconductor laser 11 for recording is adjusted in its optical axis direction and within a plane vertical to the optical axis, and the position of the other laser is adjusted within a plane vertical to its optical axis so as to secure matching with the optical axis of the adjusted laser. At the same time, the collimator lens of the other laser undergoes the transmission adjustment in its optical axis direction. Thus, the spot positions of lasers 10 and 11 are matched to each other in both tracking and focus directions of an optical card.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information recording / reproducing apparatus for recording information on an optical information recording medium or reproducing the recorded information.

[0002]

2. Description of the Related Art Various types of recording media for optically recording and reproducing information, such as discs, cards, and tapes, have been known. When information is recorded on these information recording media, irradiation is performed by irradiating a light spot having a power sufficient to cause a shape change, a reflectance change, or a structural change according to the characteristics of the recording medium.
When reproducing recorded information, the information pit array is scanned with a light spot having a constant power enough to prevent recording on the recording medium, and reflected light or transmitted light from the recording medium is detected.
The recorded information is reproduced by performing predetermined signal processing using the obtained detection signal.

An optical head used for recording and reproducing information on such a recording medium is configured to be relatively movable with respect to the recording medium in an information track direction including information pits in the information area and in a direction crossing the information track. The relative movement in both directions allows the light spot to access a desired information track and scan the information track. The optical head is provided with a focusing lens for focusing the light beam, and an objective lens is used as the lens. The objective lens is held by the optical head so that it can move independently in the optical axis direction (focus direction) and the direction perpendicular to the optical axis, that is, in the direction perpendicular to the information track of the recording medium (tracking direction). Such an objective lens is held via an elastic member, and the focus and the movement of the objective lens in the tracking direction are generally driven by an actuator utilizing magnetic interaction.

FIG. 6 is a schematic plan view of a write-once optical card. A large number of information tracks 2 and tracking tracks 4 are alternately arranged on the information recording surface of the optical card.
The optical card is provided with a home position 3 which is a reference position for accessing the information track 2. The home position 3 is used as a start position of recording and reproducing operation of information of the optical card inserted into the optical information recording / reproducing apparatus or a standby position of a light spot, and is also a retract position of the auto focus. Therefore, home position 3
Is provided with the same recording layer as the information track in order to obtain the same light reflectance as the information track. However, the tracking track is not provided because it is not necessary for the function and is a flat surface.

[0005] The information tracks 2 are arranged in the order of 2-1, 2-2, 2-3,... Further, as shown in FIG.
1, 4-2, 4-3,... These tracking tracks are auto-tracking (hereinafter referred to as AT) for controlling the light spot so as not to deviate from the target information track during light spot scanning at the time of information recording and reproduction.
Abbreviation).

In such AT control, an optical head detects a deviation (AT error) of a light spot from an information track, and feeds back to a tracking actuator that drives an objective lens in a tracking direction in an AT control circuit, so that the objective is controlled. The lens is moved in the tracking direction (D direction) to perform control so that the light spot does not deviate from the target information track. Also, when scanning a light spot on an information track at the time of recording and reproducing information, an autofocus is performed on an objective lens so that a light beam is formed into a spot of an appropriate size on the recording surface of the optical card (focusing). (Hereinafter abbreviated as AF) control. In such AF control, the optical head detects a deviation (AF error) of a light spot from a focused state, and feeds back to a focus actuator that moves the objective lens in a focus direction in an AF control circuit, thereby focusing the objective lens. The control is performed so that the light spot is focused on the recording layer of the optical card by moving the light spot in the direction.

Here, in FIG. 7, S1, S2, S3,
S4 indicates a light spot irradiated on the optical card 1. AT control is performed using the light spots of S2 and S3 of which the tracking tracks 4-2 and 4-3 are partially applied. Also, AF control and reproduction of information pits are performed using the light spot of S1, and recording of information pits is performed with the light spot of S4. In the figure, 5-1 to 3 represent information pit strings, and 6-1 to 3 represent track numbers (addresses) arranged on both sides of the information pit strings 5-1 to 5-1. Each information track is provided with a track number indicating which track the position is. Further, the width of the information track 2 which is an information area is wider than the width of the tracking track 4, and the width of the tracking track 2 is about 3 μm according to the standard.
m, the width of the information track 4 is 9 μm, and the width of the information pit is about 3
μm.

FIG. 8 is a block diagram showing an example of an optical system of an optical information recording / reproducing apparatus using an optical card as an information recording medium. In FIG. 8, reference numeral 10 denotes a reproducing semiconductor laser which is a reproducing light source, and reference numeral 11 denotes a recording semiconductor laser which is a recording light source. 12 and 13 are collimator lenses, 14 is a diffraction grating, 15 is a half mirror which is a light splitter, 16 is a dichroic prism which is an optical multiplexer, 17 is an objective lens, 18 is a spherical lens, 19 is a cylindrical lens,
20 is a photodetector. As shown in FIG. 9, the photodetector 20 includes four divided light receiving elements 20-1 to 20-4 and a light receiving element 2
0-5 and 20-6.

The light beam emitted from the reproducing semiconductor laser 10 is a linearly polarized light beam perpendicular to the plane of FIG. 8 and becomes a parallel light beam by the collimator lens 12 and is incident on the diffraction grating 14. Is divided into Of the divided diffracted light, the 0th-order diffracted light is used for information reproduction and AF control.
The two ± first-order diffracted lights are used for AT control. The three diffracted light beams are reflected by the half mirror 15, pass through the dichroic prism 16, and enter the objective lens 17.
The light beam incident on the objective lens 17 is focused on a light spot,
The light is focused on the optical card 1. The focused light is the minute light spots S2 (+ 1st-order diffracted light), S1 (0th-order diffracted light), and S3 (-1st-order diffracted light) shown in FIG. Light spot S1
Are used for reproduction and AF control as described above, and S2 and S3
Is used for AT control.

The position of the spot on the optical card 1 is
As shown in FIG. 7, the light spots S2 and S3 are located on two adjacent tracking tracks, and the spot S1 is an information track 2 which is an information area between the tracking tracks.
Located on top. Note that the degree of tracking tracks of the light spots S2 and S3 is finely adjusted by rotating the diffraction grating 14 about the optical axis so that desired AT control can be performed. Thus, the light spot is irradiated on the optical card 1, and a part of the light spot is reflected on the optical card surface and enters the objective lens 17. This reflected light is transmitted through the dichroic prism 16 and the half mirror 15 and becomes a spherical lens 18.
Then, the light passes through a sensor lens system including the cylindrical lens 19 and enters the photodetector 20.

On the other hand, the luminous flux emitted from the recording semiconductor laser 11 is a linearly polarized luminous flux parallel to the plane of FIG. 8, converted into a parallel luminous flux by the collimator lens 13, reflected by the dichroic prism 16, and reflected by the objective lens 17 by an optical card. 1 onto a light spot. Information recording is performed by the irradiated light spot. Part of the recording light is reflected by the optical card 1, passes through the objective lens 17, and is reflected by the dichroic prism 16. Here, the wavelength characteristics of the semiconductor lasers 10 and 11 and the wavelength characteristics of the half mirror 15 and the dichroic mirror 17 will be described. The wavelength of the reproducing semiconductor laser is, for example, 790 nm, and the wavelength of the recording semiconductor laser is 830 nm.

The wavelength characteristic of the half mirror 15 is 790
Between nm and 830 nm, about 50% of the P-polarized light component and about 50% of the S-polarized light component are transmitted and about 50% reflected. The wavelength characteristics of the dichroic prism 16 are such that a P-polarized component having a wavelength of 830 nm is substantially reflected, and an S-polarized component is substantially transmitted. Further, a film having a property of transmitting the P-polarized component and the S-polarized component of 790 nm is deposited. Therefore, the light emitted from the recording semiconductor laser 11 having a wavelength of 830 nm is reflected by the optical card 1 and returns to the semiconductor laser 11 again. Also, 7
The 90 nm light emitted from the reproducing semiconductor laser 10 is reflected by the optical card 1 and travels to the photodetector 20.

FIG. 9 is a circuit diagram showing a signal processing circuit.
In FIG. 9, reference numeral 20 denotes the photodetector of FIG. 8, and as described above, the light receiving elements 20-5 and 20-6 and the four-division light receiving element 20 are used.
-1 to -4. Light spots S1, S2, and S3 on the light receiving surface of each light receiving element indicate reflected light from the optical card. The AT control light spots S2 and S3 are received by the light receiving elements 20-5 and 20-6, respectively, and the AF control and reproduction light spot is received by the four divided light receiving elements 20-1 to 20-4. The output signals of the light receiving elements 20-5 and 20-6 are output to a subtraction circuit 122, and the subtraction circuit 122 detects the difference to generate an AT control signal. The output signals of the quadrant light receiving elements 20-2 and 20-4 are added to the addition circuit 11
At 1, the output signals of the light receiving elements 20-1 and 20-3 are added by the adding circuit 112, respectively. Addition circuits 111 and 11
The difference between the two output signals is detected by the subtraction circuit 121 and output as an AF control signal. Also, the adders 111 and 11
The outputs of 2 are added by the adder circuit 113, and the sum signal of the four divided light receiving elements is output as the information reproduction signal RF.

The AT control signal is output to an AT control circuit (not shown).
By driving an actuator (not shown), the objective lens 17 is driven.
AT in the tracking direction to perform AT control. Further, an AF control circuit (not shown) drives an AF actuator (not shown) based on the AF control signal, and performs AF control by displacing the objective lens 17 in the focus direction. For reproducing information, a light beam for reproduction is scanned on the track of the optical card while performing AT / AF control, and a predetermined signal processing such as binarization and demodulation is performed in a reproduction circuit (not shown) using the information reproduction signal RF. To reproduce the recorded information. When recording information, the recording data is modulated by a predetermined modulation method, and the recording semiconductor laser 11 is driven according to the obtained recording signal. Then, information recording is performed by scanning a target track with a recording light beam whose intensity is modulated according to a recording signal while performing AT / AF control.

Next, a method for fixing the semiconductor laser 10 for reproduction and the collimator lens 12 and a method for adjusting the position will be described with reference to FIG. In FIG. 10, 40 is an optical head housing, 41 is an LD holder, and 42 and 43 are adhesives cured by ultraviolet rays. Reference numeral 10 denotes a reproducing semiconductor laser, and reference numeral 12 denotes a collimator lens. This position adjustment is performed by adjusting the optical axis of the light beam emitted from the collimator lens 12 to substantially coincide with the ideal optical axis indicated by a dashed line, and converting the divergent light emitted from the reproducing semiconductor laser 10 into a parallel light beam by the collimator lens 12. There is a collimation adjustment.
The optical axis adjustment is performed by using an adjustment jig (not shown) to move the LD holder 41 holding the reproduction semiconductor laser 10 in a plane perpendicular to the ideal optical axis so that the light of the reproduction semiconductor laser comes to the target position. Done by

Next, in the collimation adjustment, the LD holder 41 is ideally set so that the light from the reproducing semiconductor laser 10 is focused on the target position (in this state, the light emitted from the collimator lens is a parallel light beam). It is performed by moving in the optical axis direction. When the position adjustment is completed, the adhesives 42 and 4 are set in the gap between the head housing 40 and the LD holder 41.
3 is injected and fixed by irradiating ultraviolet rays. The adjustment of the recording semiconductor laser 11 and the collimator lens 13 is performed in exactly the same manner as the reproduction semiconductor laser. In adjusting the recording semiconductor laser, a reproduction light can be used as a target. It is desirable to use a reproduction light beam as a target because an adjustment error of the reproduction semiconductor laser can be removed.

[0017]

What is important in the above-mentioned conventional optical head comprising two light sources is that the reproducing light spot and the recording light spot are focused on the medium surface of the optical card, and That is, the reproduction light spot and the recording light spot are located substantially at the center of the information track. Conventionally, the position of the reproducing light spot and the position of the recording light spot have been adjusted by adjusting the optical axes of both light sources and collimating. The semiconductor laser is moved in the optical axis direction with respect to a collimator lens adhesively fixed to the head housing. The position is adjusted in a plane perpendicular to the optical axis, that is, three-dimensionally, and fixed with an ultraviolet-curing adhesive.

However, the fixing method using an adhesive has the following problems. That is, the adhesive always shrinks during curing, and the amount of shrinkage varies depending on the amount of the adhesive. However, if the gap between the LD holder and the head housing, that is, the thickness of the adhesive is several hundred microns, the shrinkage occurs. The amount is a few microns. FIG. 11 shows a fixed state of a conventional recording semiconductor laser 11. 40 is a head housing, 41
Is an LD holder, and 42 and 43 are adhesives. Also,
Numeral 11 denotes a recording semiconductor laser, and numeral 13 denotes a collimator lens.

The position adjustment of the recording semiconductor laser is performed so as to coincide with the reproduction light spot from the reproduction semiconductor laser whose position has already been adjusted. Here, there is no problem even if the position of the semiconductor laser is shifted by several microns due to shrinkage of the adhesive when bonding the LD holder 41 of the semiconductor laser 10 for reproduction. This means that if the reproducing semiconductor laser deviates from its normal position and is no longer a perfectly parallel light beam, but only a few microns, the divergence or convergence of light is very small,
This is because it can be considered as a substantially parallel light beam. If the displacement is several microns, the diameter of the light spot on the optical card surface hardly changes, and no problem occurs.

However, in the case of the recording semiconductor laser, since the adjustment is performed using the reproduction light spot as a target, the displacement of the recording semiconductor laser caused by the contraction of the adhesive becomes a serious problem. In particular, in the case of the bonding method shown in FIG. 11, displacement of the light spot due to contraction in the optical axis direction becomes a problem. That is, since information is recorded while performing AF control using the reproduction light spot, if the recording light spot and the reproduction light spot are displaced in the optical axis direction, the recording spot on the optical card is defocused. Therefore, a predetermined pit shape cannot be obtained with an increase in recording pits or a decrease in power density. As a result, information cannot be accurately recorded, the intensity of the reproduced signal is reduced, and the shape of the signal waveform is changed, so that the quality of the reproduced signal is significantly deteriorated. Since the optical depth of focus of each spot is 2 to 3 microns, the allowable displacement of the two spots for ensuring a high-quality reproduction signal must be 1 micron or less.

In order to solve this problem, the recording light spot is shifted in advance by the contraction amount by taking the contraction amount of the adhesive into consideration, and the LD of the recording semiconductor laser is adjusted.
Although it is conceivable to bond the holder, the amount of shrinkage changes sensitively depending on the curing conditions of the adhesive, such as the amount of ultraviolet light, temperature, irradiation distance, irradiation time, and the amount of adhesive. There was a problem that the cost was high, not for mass production.

In view of the above-mentioned conventional problems, the present invention prevents an optical axis direction displacement between a recording light spot and a reproducing light spot, and can record information accurately. The purpose is to provide.

[0023]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording light source, a first collimator lens for collimating a divergent light beam emitted from the recording light source, a reproducing light source, and a reproducing light source. A second collimator lens that collimates the emitted divergent light beam, and records information by irradiating a recording light beam from the recording light source onto a recording medium, and outputs a reproduction light beam from the reproduction light source. In an optical information recording / reproducing apparatus that irradiates a recording medium and reproduces recorded information based on light reflected by the recording medium, one of the first and second light sources is an optical axis direction and an optical axis direction. The other light source is aligned in a plane perpendicular to the optical axis so as to coincide with the optical axis of the light flux of the adjusted light source, and a collimator on the other light source side Adjust the position of the lens in the optical axis direction By Rukoto, the first is achieved by an optical information recording and reproducing apparatus spot position of the second light source is characterized in that substantially coincides with the tracking and focusing directions of the recording medium.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the optical information recording / reproducing apparatus according to the present embodiment uses the optical system (optical head) of FIG. 8 and the signal processing circuit of FIG. 9, and uses the optical card 1 of FIG. 6 as a recording medium. The optical system of FIG. 8 and the optical card 1 are relatively moved in the track direction by a moving mechanism (not shown), and the recording / reproducing light spot is scanned from the optical system to the target track of the optical card 1 while performing AT / AF control. Thus, recording / reproduction of information is performed. AT / A
The F control and the recording / reproducing operation of the information are as described in the related art.

FIG. 1 shows a recording semiconductor laser 1 in an optical head.
FIG. 2 is a diagram showing a holding structure of No. 1. 50 is a head housing, 51
Are an LD holder for holding the recording semiconductor laser 11, and 5
2 is a lens holder for holding the collimator lens 13,
53 and 54 are adhesives for bonding the LD holder 51 to the head housing 50. The adhesives 53 and 54 are to be cured by ultraviolet rays. Note that the holding structure of the reproducing semiconductor laser 10 is exactly the same as the conventional structure shown in FIG. That is, the LD holder 41 holding the semiconductor laser 10 for reproduction is bonded and fixed to the head housing 40 using an adhesive.

Next, a method for adjusting the positions of the semiconductor lasers for reproduction and recording will be described with reference to FIG. The adjustment of the reproducing semiconductor laser 10 is shown in FIG.
The adjustment of 1 will be described with reference to FIG. 1 and 10 in FIG.
Numeral 40 indicates the same head housing. In FIG. 2, 60 is a TV camera, and 61 is a target chart. These are adjustment jigs used for position adjustment.
The rest is an optical system including a semiconductor laser to be adjusted, which is exactly the same as FIG. All components such as the photodetector 20 and the objective lens 17 in these optical systems are the head housing 50 of FIG.
Is held within. The dashed line in FIG. 2 indicates the ideal optical axis.

Here, the target chart 61 is shown in FIG.
As shown in the figure, there is a crosshair, which is used to adjust the light flux of each semiconductor laser so as to match the ideal optical axis. The target chart 61 has substantially the same refractive index and thickness as the transparent protective substrate (the transparent substrate on the light incident side) of the optical card 1, and the cross line is located on the surface on the TV camera 60 side. Further, the LD holders for holding the semiconductor laser 10 for reproduction and the semiconductor laser 11 for recording in FIG. 2 are held by adjusting jigs for moving in the optical axis direction and in a plane perpendicular to the optical axis, respectively.

To adjust the position of the semiconductor laser 10 for reproduction, the target chart 61 is arranged at the position of the optical card, and the TV camera 60 is focused on the target chart 61. Next, the reproduction semiconductor laser 10 is caused to emit light, and the reproduction light beam and the target chart 61 are observed by the TV camera 60 so that the center of the reproduction light beam and the intersection of the cross line of the target chart 61 coincide with each other. The LD holder 41 holding 10 is moved in a plane perpendicular to the ideal optical axis indicated by a chain line. Further, the LD holder 41 is moved in the ideal optical axis direction so that the light beam from the reproducing semiconductor laser 10 is focused on the surface of the target chart 61. After the focusing of the reproducing light spot on the surface of the target chart 61 is completed, an adhesive is injected into a gap between the head housing 40 and the LD holder 41, and is fixed by irradiating ultraviolet rays.

When the position adjustment of the reproduction semiconductor laser 10 is completed, the position adjustment of the recording semiconductor laser 11 is performed. First, the recording semiconductor laser 11 is caused to emit light, and the TV camera is set so that the center of the reproduction light spot and the center of the recording light spot coincide (or coincide in the tracking direction) with the reproduction light spot as a target. While observing at 60, the LD holder 51 holding the recording semiconductor laser 11 is moved in a plane perpendicular to the ideal optical axis. When they match, as shown in FIG. 1, adhesives 53 and 54 are injected into the gap between the head housing 50 and the LD holder 51, and are fixed by irradiating ultraviolet rays. FIG. 4 shows the position adjustment direction (xy in the figure) of the recording semiconductor laser 11 and the collimator lens 13 in a plane perpendicular to the ideal optical axis in this case.

Next, the lens holder 52 holding the collimator lens 13 is moved in the optical axis direction so that the focal point of the recording light spot coincides with the focal position of the reproducing light spot. When the positions match, an adhesive is injected between the lens holder 52 and the head housing 50, or
An adhesive is applied so as to bridge the head housing and is fixed by irradiating ultraviolet rays. FIG. 5 shows the adjustment direction (z in the figure) of the collimator lens 13. Here, in the present embodiment, since the bonding direction of the lens holder 52 and the head housing 50 is perpendicular to the ideal optical axis, the contraction direction of the adhesive generated during bonding is perpendicular to the ideal optical axis, and And the recording spot does not shift in the optical axis direction. Therefore, even if the adhesive contracts, the recording light spot does not become defocused, and information can be recorded correctly.

In the above embodiment, the reproduction semiconductor laser is adjusted in the optical axis direction and in a plane perpendicular to the optical axis, the recording semiconductor laser is adjusted in the plane perpendicular to the optical axis, and the recording semiconductor laser is adjusted. The collimator lens 13 on the side is adjusted in the optical axis direction. Conversely, the recording semiconductor laser is adjusted in the optical axis direction and in a plane perpendicular to the optical axis, and the reproducing semiconductor laser is adjusted in the plane perpendicular to the optical axis. After the adjustment, the collimator lens on the side of the semiconductor laser for reproduction may be adjusted in the optical axis direction. Also in this case, even if the adhesive contracts, an optical head which is not affected by the contraction can be achieved. However, the adjustment procedure in this case is
First, the position of the recording semiconductor laser is adjusted, and the position of the reproducing semiconductor laser is adjusted using the recording light spot as a target.

In the prior art, if the deviation between the reproducing light spot and the recording light spot is large, readjustment is required. In the present embodiment, the deviation between the two light spots is adjusted by adjusting the position of the collimator lens. Since the correction can be performed, readjustment is not required, and the adjustment time can be reduced.

[0033]

As described above, according to the present invention, the reproduction light spot and the recording light spot due to the shrinkage of the adhesive for adhering the holding member for holding the recording light source and the reproduction light source to the housing are provided. Since the position deviation of the light spot in the optical axis direction can be eliminated and the recording light spot does not record in a defocused state, information can be accurately recorded at the time of recording and a high-quality reproduction signal at the time of reproduction. And a highly reliable recording / reproducing apparatus can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing an optical system and an adjustment jig.

FIG. 3 is a diagram showing a target chart of an adjustment jig.

FIG. 4 is a diagram showing an adjustment direction in a plane perpendicular to an ideal optical axis of the recording semiconductor laser.

FIG. 5 is a diagram showing an adjustment direction of a collimator lens on the recording semiconductor laser side.

FIG. 6 is a plan view of the optical card.

FIG. 7 is a diagram showing a light spot on an optical card.

FIG. 8 is a diagram showing an optical system of a conventional optical card recording / reproducing apparatus.

FIG. 9 is a diagram showing a signal processing circuit of a conventional optical card recording / reproducing device.

FIG. 10 is a view showing a holding structure of a reproducing semiconductor laser of the optical system of FIG. 8;

11 is a diagram showing a holding structure of the recording semiconductor laser of the optical system of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical card 10 Semiconductor laser for reproduction 11 Semiconductor laser for recording 12, 13 Collimator lens 17 Objective lens 20 Photodetector 50 Head housing 51 LD holder 52 Lens holder 53, 54 Adhesive 60 TV camera 61 Target chart

Claims (3)

[Claims] 1. A recording light source, a first collimator lens for collimating a divergent light beam emitted from the recording light source, a reproduction light source, and a second collimator for collimating the divergent light beam emitted from the reproduction light source. A collimator lens for recording information by irradiating the recording medium with the recording light beam from the recording light source, irradiating the recording medium with the reproducing light beam from the reproducing light source, and reflecting the light from the recording medium. In an optical information recording / reproducing apparatus that reproduces recorded information based on light, one of the first and second light sources is position-adjusted in the optical axis direction and in a plane perpendicular to the optical axis. The other light source is adjusted in position in a plane perpendicular to the optical axis so as to coincide with the optical axis of the light flux of the adjusted light source, and adjusts the position of the collimator lens on the other light source side in the optical axis direction. By doing so, the first and second An optical information recording / reproducing apparatus, wherein the spot positions of the two light sources substantially match in the tracking direction and the focus direction of the recording medium. 2. The first and second light sources include first and second light sources.
2. The optical information recording / reproducing apparatus according to claim 1, wherein the optical information recording / reproducing apparatus is fixed to an enclosure holding the collimator lens with an adhesive. 3. The optical information recording / reproducing apparatus according to claim 2, wherein the adhesive is cured by ultraviolet rays.