JP2810434B2 - Method and fixture for fixing beam splitter of optical system for optical information recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses a laser beam emitted from a laser diode or the like to record and reproduce information on a storage medium such as a magneto-optical disk. The present invention relates to a beam splitter fixing method and a jig for an optical system for an optical information recording / reproducing apparatus.

[Prior Art] In an optical system for an optical information recording / reproducing apparatus, generally, a laser beam is divided by a beam splitter, and the divided laser beam is irradiated on a photoelectric element or the like to extract a signal. If the light flux is not accurately incident on the photoelectric element or the like, the signal cannot be correctly extracted. Therefore, the beam splitter must precisely adjust and fix the position and orientation of the light-splitting surface (semi-transmissive surface).

Therefore, all optical elements such as laser diodes are arranged in the device, and the laser beam actually emitted from the laser diode and the laser beam focused by the objective lens and reflected from the storage medium are separated by a beam splitter, and the photoelectric element is mounted. While detecting or observing the laser beam at the position,
By adjusting the position and orientation of the beam splitter, it is possible to fix the beam splitter to a relatively accurate state. However, in recent years, generally, a beam splitter is fixed by a so-called UV bonding method in which the beam splitter is bonded by irradiating ultraviolet rays. Therefore, ultraviolet rays have an adverse effect on optical elements other than the beam splitter, such as a laser diode.

Therefore, conventionally, the position of the beam splitter is adjusted and fixed by a mechanical jig before attaching another optical element.

[Problems to be Solved by the Invention] However, there is a variation between the external shape of the beam splitter and the position and angle of the semi-transparent surface depending on components. Therefore, in the conventional method of adjusting and fixing the position of the beam splitter with a mechanical jig, an error occurs in the position and orientation of the semi-transparent surface, and the laser beam is accurately irradiated on the photoelectric element. There is a disadvantage that the signal cannot be correctly extracted.

The present invention solves such a conventional drawback, and can accurately adjust the position and orientation of the semi-transparent surface without fixing other optical elements and the like, thereby fixing the beam splitter, It is an object of the present invention to provide a method for fixing a beam splitter of an optical system for an optical information recording / reproducing apparatus, which can accurately take out a beam, and a jig used for the method.

Means for Solving the Problems In order to achieve the above object, a beam splitter fixing method of the present invention provides an objective optical system that focuses a laser beam emitted from a laser light source on a storage medium along a guide rail. An optical system for an optical information recording / reproducing apparatus, which is provided movably, and has a beam splitter fixed on the laser beam path parallel to the guide rail, and irradiates a photoelectric element with a laser beam split by the beam splitter. In the beam splitter fixing method, a jig provided with an auxiliary laser light source that emits an auxiliary laser beam for adjustment is mounted on a mounting portion for mounting the guide rail, and from the auxiliary laser light source, in parallel with the guide rail, A laser beam is emitted so as to coincide with the optical axis of the laser beam path, and the laser beam is incident on the beam splitter. The position of the beam splitter is adjusted and fixed while observing the laser beam split by the beam splitter at the position where the photoelectric element is mounted.

Further, the jig for fixing the beam splitter of the optical system for an optical information recording / reproducing device of the present invention includes an objective optical system for focusing a laser beam emitted from a laser light source on a storage medium,
In an optical system for an optical information recording / reproducing device movably provided along a guide rail, a laser beam parallel to the guide rail is detachably mounted on a mounting portion for mounting the guide rail, and the laser beam is parallel to the guide rail. An auxiliary laser light source that emits light in accordance with the axis of the optical system is provided.

[Operation] In an optical system for an optical information recording / reproducing apparatus, generally, when a laser beam parallel to a guide rail is reflected on a storage medium, the reflected beam always travels along an original optical path parallel to the guide rail. Go back.

So, with the guide rail removed from the device,
Attach the jig to the mounting part for mounting the guide rail. Next, a laser beam is emitted from the auxiliary laser light source of the jig so as to be parallel to the guide rail and coincide with the optical axis of the laser beam path of the apparatus, and the emitted beam is split by a beam splitter.

Then, if the semi-transmissive surface of the beam splitter is arranged at an appropriate position and orientation, the laser beam from the auxiliary laser light source divided by the beam splitter will accurately enter the center of the mounting position of the photoelectric element. Therefore, the laser beam split by the beam splitter is observed at the mounting position of the photoelectric element, and the position and the direction of the beam splitter are adjusted so that the laser beam is incident on the center of the mounting position of the photoelectric element. To the device.

Example An example will be described with reference to the drawings.

FIG. 5 shows an optical system for an optical information recording / reproducing apparatus. In the figure, reference numeral 1 denotes a magneto-optical disk serving as an information storage medium, which is provided so as to rotate about an axis 2. In FIG. 5, the magnetic thin film 1a formed on the upper surface of the magneto-optical disk 1 is irradiated with a laser beam to change the direction of the magnetism of the magnetic thin film 1a only at the irradiated spot (pit), thereby obtaining digital information. Is stored.

This information can be easily written and read, but in order to perform it accurately, it is necessary to precisely focus the spot of the laser beam on the magnetic thin film 1a of the magneto-optical disk 1 with a diameter of about 1 μm. There is.

10 is a laser diode (LD) 11 and a collimator lens
And a laser pen 11 that emits a laser beam that spreads in an elliptical shape. Also, the collimator lens 12 is
A laser diode 11 is arranged near a focal position of a collimator lens 12 to convert a laser beam emitted from the laser beam into a parallel beam.

Reference numeral 13 denotes an anamorphic prism, which refracts and magnifies a laser beam incident on an elliptical cross section only in a direction (paper direction in FIG. 5) that is horizontal to the joint surface of the laser diode 11 and emits the beam as a circular cross section.

15 is a fixed mirror, 16 is a movable mirror, and both mirrors are arranged facing each other. Then, the laser beam transmitted through the anamorphic prism 13 is reflected by the fixed mirror 15, then reflected by the movable mirror 16, and is reflected by the objective lens 17.
And converges on the surface of the magnetic thin film 1a of the magneto-optical disk 1.

Reference numeral 18 denotes a carriage on which the movable mirror 16 and the objective lens 17 are mounted. As shown in FIG. 3, the carriage 18 is provided with a plurality (for example, three) of wheels 18a across the optical axis. However, in FIG.
The objective lens 17 has been removed from the carriage 18.

In FIG. 3, reference numerals 40 and 41 denote cylindrical reference guide rails and auxiliary guide rails having a uniform diameter. Two wheels 18a are engaged with the reference guide rail 40, and the auxiliary guide rails 41 are provided.
, Only one wheel 18a is engaged. In this way, the carriage 18 is moved by the two guide rails 4 via the wheels 18a.
0, 41, and can access the magneto-optical disk 1 by moving in the direction of arrow A along the radial direction of the disk 1.

Reference numerals 42 and 43 denote reference mounting portions and auxiliary mounting portions for detachably mounting the reference guide rails 40 and the auxiliary guide rails 41, respectively. Bases for fixing the optical elements of the optical system for the optical information recording / reproducing apparatus are provided. A pair is integrally formed on the 50 and protrudes. In the reference mounting part 42,
Horizontal seat that supports the reference guide rail 40 closely from below
42a and a vertical seat 42b that is closely attached and supported from the side are formed. An auxiliary guide rail is provided on the auxiliary mounting section 43.
A horizontal seat 43a that supports 41 from below is formed so as to be parallel to the horizontal seat 42a of the reference mounting portion 42.

Returning to FIG. 5, reference numeral 20 denotes a fixed mirror 15 and a movable mirror.
16 is a beam splitter fixedly provided. Here, first, the light beam incident from the fixed mirror 15 side is
At the first semi-transparent surface 20a on the 16 side, the light is divided at right angles to the side (I direction), passes through the first condenser lens 21, and converges on the first photoelectric element 22 for laser output monitoring.

The reflected light flux reflected from the magneto-optical disk 1 through the beam splitter 20 passes through the same optical axis as that at the time of incidence, and
The first semi-permeable surface 20a of the beam splitter 20 is divided into a direction (J direction) 180 degrees opposite to the above-mentioned I direction.
Then, the split light beam passes through the half-wave plate 25 and the direction of the polarization plane is rotated by 45 degrees. Then, the light beam is further divided by a sub-beam splitter 26 by a polarization reflection surface which forms an angle of 45 degrees with the polarization direction, passes through second and third condenser lenses 27 and 28, and is used for S-polarization intensity detection and P-polarization intensity detection. To the second and third photoelectric elements 29 and 30. Information is read by the output signals of the second and third photoelectric elements 29 and 30.

In the second semi-permeable surface 20b of the beam splitter 20, the above-described J
The reflected light flux from the magneto-optical disk 1 divided in a direction parallel to the direction (J2 direction) passes through a fourth condenser lens 34 and a cylindrical lens 35, and outputs a servo signal for performing a focus and tracking. Focus on a fourth optoelectronic device 36 for output.

The focus servo finely moves the objective lens 17 in the direction B, that is, in the direction perpendicular to the surface of the magneto-optical disk 1, and focuses the minimum spot of the laser beam on the magnetic thin film 1a of the magneto-optical disk 1.
Focus on the surface. The tracking servo uses the objective lens 17
Is finely moved in the direction A, that is, in the direction perpendicular to the information recording track of the optical disk 1, and the laser beam is controlled so as not to protrude from the track. In the present embodiment, the light receiving surface of the fourth photoelectric element 36 is divided into, for example, four or more, and signals for focus servo and tracking servo can be obtained by combining output signals from the respective parts.

1 and 2 show an apparatus for adjusting the position of the beam splitter 20. FIG. In the figure, reference numeral 50 denotes an optical element including the beam splitter 20 and a base having both mounting portions 42 and 43. The base 50 has a first photoelectric element fixing hole 53 for fixing the first photoelectric element 22 for monitoring the laser output, so that the light receiving portion of the first photoelectric element 22 can be arranged at the center thereof. Has been established. Further, the second and third photoelectric elements 29 and 30 for detecting the S polarization intensity and the P polarization intensity are used.
And third photoelectric element fixing holes 55 and 57 for fixing
Are provided so that the light receiving portions of the second and third photoelectric elements 29 and 30 can be arranged at the respective centers.

Reference numeral 401 denotes a reference jig for performing positioning adjustment of the beam splitter 20, and can be detachably attached to the attachment portions 42, 43 with the guide rails 40, 41 removed. The reference jig 401 includes the beam splitter 20
An auxiliary laser pen 402 including an auxiliary laser diode 402a and a collimator lens 402b is provided so as to emit an auxiliary laser beam for adjustment toward the fixed position of the laser beam. The auxiliary laser pen 402 is located on the bottom surface 401a of the reference jig 401.
The emission direction is set so that the laser beam can be emitted horizontally to the side surface 401b. When the reference jig 401 is attached to the guide rail attachment portions 42 and 43, the optical axis of the laser pen 402 Coincides with the optical axis of the laser beam of the optical system. The side surface of the reference jig 401 is formed so as to have a slight gap between the side surface of the reference jig 401 and the auxiliary mounting portion 43.

Reference numeral 420 denotes an adjustment jig in which a rod 422 is connected to the lower surface of the handle 421. The tip of the rod 422 is attached to the upper surface of the beam splitter 20, and the handle 421 is moved in the direction of arrow R around the axis of the rod 422. By rotating, the semi-transparent surface of the beam splitter 20
20a and 20b can be rotated in a plane parallel to the base 50. Further, by moving the handle 421 in the direction of arrow K along the optical axis of the auxiliary laser pen 402, the semi-transparent surfaces 20a and 20b of the beam splitter 20 can be moved in parallel back and forth.

430 is a corner cube prism whose apex is arranged on an extension of the optical axis of the auxiliary laser pen 402, and reflects the laser beam emitted from the auxiliary laser pen 402 and transmitted through the beam splitter 20 in a direction opposite to 180 degrees. Can be done. 460 and 470 are known image pickup devices, which are arranged so as to form images at the positions of the first and second photoelectric element fixing holes 53 and 55 on the image forming surfaces 464 and 474 by the objective lenses 462 and 472, respectively. The images of the fixing holes 53 and 55 are displayed on the monitors 468 and 478, respectively. Reference numerals 466 and 476 denote polarization filters independently and rotatably provided around the optical axis for adjusting the amount of light.

Next, a beam splitter fixing method according to the present embodiment will be described.

As shown in FIG. 4, the reference guide rail 40 and the auxiliary guide rail 41 are detached from both the mounting portions 42 and 43. Then, as shown in FIG. 1 and FIG. 2, the reference jig 401 is attached to both attachment portions 42 and 43. At this time, the reference jig 401 is attached so that the auxiliary laser pen 402 faces the position where the beam splitter 20 is fixed.
The reference jig 401 is placed on both the mounting portions 42 and 43 so that the bottom surface 401a of the reference jig 401 is in close contact with 2a and 43a, and the side surface 401b of the reference jig 401 is closely attached to the vertical seat 42b. . As described above, when the reference jig 301 is attached to both the attachment portions 42 and 43, the laser beam from the auxiliary laser pen 402 is horizontal with respect to the reference guide rail 40, and the information recording / reproducing optical system is used. It coincides with the optical axis of the laser beam.

Next, a laser beam is emitted from the auxiliary laser pen 402, and the beam splitter 20 is placed on the base 50 so that the laser beam passes through the two semi-permeable surfaces of the beam splitter 20. The beam splitter placed in this way
20 is provided with a first condenser lens 21 and a half-wave plate 25 in advance.
And the sub-beam splitter 26 and the second and third condenser lenses 27 and 28 are joined in advance. And beam splitter 2
The adjustment jig 420 is attached and placed on the upper surface of the zero.

Then, the laser beam emitted from the auxiliary laser pen 402 passes through the first semi-transmissive surface 20 a of the beam splitter 20.
Divided into two. Then, the light beam reflected in the J direction at right angles passes through the half-wave plate 25, is reflected by the polarization reflection surface of the sub-beam splitter 26, and is reflected by the second condenser lens 27 into the second light beam. Is focused near the center of the photoelectric element fixing hole 55. Therefore, the focus of the objective lens 472 of the image pickup device 470 is aligned with the fixing hole 55, and the image of the focal point is formed by the image pickup device
An image is formed on the imaging plane 474 of 0 and is projected on the monitor 478.

The laser beam transmitted through the first semi-transmissive surface 20a is emitted to the outside of the beam splitter 20, then reflected by the corner cube rhythm 430 in the opposite direction, and again enters the beam splitter 20 from the opposite direction. . And the first
Is reflected in the I direction opposite to the J direction on the semi-transparent surface 20a of
By the first condenser lens 21, the first photoelectric element fixing hole 53 is formed.
Focus near the center of. Then, the focus of the objective lens 462 of the imaging device 460 is adjusted to the fixing hole 53, and the image of the focal point is formed on the imaging surface 464 of the imaging device 460, and the monitor 46
8

Then, as shown in FIGS. 6A and 6B, the monitor
At 468 and 478, the images S1 and S2 of the photoelectric element fixing holes 53 and 55 and the convergence points converging near their centers are observed, respectively. Therefore, at this time, the positions and orientations of the imaging devices 460 and 470 are adjusted so that the reference points 468a and 478a attached to the monitors 468 and 478 match the centers of the photoelectric element fixing holes 53 and 55, respectively.

When the adjustment jig 420 is rotated about the axis of the rod 422 in the direction of arrow R, it is possible to adjust the images S1 and S2 to move in directions R1 and R2 different from each other. When the adjustment jig 420 is moved back and forth in the direction of arrow K along the optical axis of the auxiliary laser pen 402, the images S1 and S2 are oriented in the same directions K1 and K2.
Can be adjusted to move.

As described above, the images S1 and S2 are moved on the monitors 468 and 478, and the images S1 and S2 are both moved to the reference points 468 of the monitors 468 and 478.
a, 478a, by adjusting the position of the beam splitter 20, the laser beam from the auxiliary laser pen 402,
This means that the light is accurately focused on the centers of the photoelectric element fixing holes 53 and 55. The optical axis of the auxiliary laser beam for adjustment emitted from the auxiliary laser pen 402 coincides with the optical axis of the laser beam of the information recording / reproducing optical system. If the beam is focused on the center of 53, 55, the laser beam of the information recording / reproducing optical system will also be focused on the center of each photoelectric element fixing hole 53, 55. And the orientation is correctly adjusted.

According to this embodiment, as described above, the beam splitter
The position and orientation of the semi-transparent surface 20a of the beam splitter 20 can be adjusted very accurately and easily with respect to the photoelectric element fixing holes 53 and 55 provided on both sides of the beam splitter 20.

When the position adjustment of the beam splitter 20 is completed in this way, the beam splitter 20 is fixed to the base 50 by, for example, a UV bonding method of bonding by irradiation of ultraviolet rays.

Note that the direction of the laser beam that can be adjusted in the above embodiment is only in the direction horizontal to the base surface (in the plane of the paper), and cannot be adjusted in the direction perpendicular to the base surface. However, if an error exceeding the tolerance has occurred, the beam splitter may be replaced before fixing it to the base, and it is not necessary to replace all optical components after arrangement.

[Effects of the Invention] According to the present invention, the beam splitter can be fixed by accurately adjusting the position and the direction of the semi-transparent surface irrespective of the outer shape of the beam splitter. It has excellent effects such as being able to accurately irradiate the center and to take out signals accurately, and to reduce the angle tolerance of the semi-transparent surface with respect to the outer surface of the beam splitter to reduce costs. is there.

In addition, since the beam splitter can be adjusted and fixed without attaching a laser diode or the like of an optical system for an information recording / reproducing device, the beam splitter can be used in the UV mode.
Adhesion does not adversely affect the laser diode or the like due to ultraviolet light.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of the present invention, FIG. 2 is a perspective view thereof, FIG. 3 is an enlarged perspective view of a guide rail portion, FIG. The figure is a schematic view of an optical system for an optical information recording / reproducing apparatus, FIGS. 6A and 6B are schematic views of a monitor screen when a beam splitter is rotated, and FIGS. 7A and 7B show a beam splitter. It is a schematic diagram of a monitor screen at the time of moving back and forth. 1 ... magneto-optical disk, 10 ... laser pen, 11 ... laser diode, 15 ... fixed mirror, 16 ... movable mirror,
17 Objective lens 18 Carriage 40 Reference guide rail 41 Auxiliary guide rail 43 Reference mounting part 43 Auxiliary mounting part 401 Reference jig 420 Adjustment Jig, 430… Corner cube prism, 460,470 ……
Imaging device, 468,478 ... Monitor.

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Claims (2)

(57) [Claims] An objective optical system for focusing a laser beam emitted from a laser light source on a storage medium is provided along a guide rail so as to be movable, and a beam splitter is fixed on the laser beam path parallel to the guide rail. Then, in the beam splitter fixing method of the optical system for an optical information recording / reproducing apparatus, in which the laser beam split by the beam splitter is irradiated to the photoelectric element, an auxiliary laser light source for emitting an auxiliary laser beam for adjustment is provided. Attach the jig to the mounting part for mounting the guide rail, from the auxiliary laser light source, in parallel with the guide rail,
A laser beam is emitted so as to coincide with the optical axis of the laser beam path, the laser beam is incident on the beam splitter, and the laser beam split by the beam splitter is observed at the mounting position of the photoelectric element, A beam splitter fixing method for an optical system for an optical information recording / reproducing apparatus, wherein the position of the beam splitter is adjusted and fixed. 2. An optical system for an optical information recording / reproducing apparatus, wherein an objective optical system for focusing a laser beam emitted from a laser light source on a storage medium is movably provided along a guide rail. An optical information recording device, which is provided with an auxiliary laser light source which is detachably attached to an attachment portion for attachment and emits a laser beam parallel to the guide rail so as to coincide with the axis of the objective optical system. A jig for fixing the beam splitter of the optical system for the playback device.