JPH0743508A - Production of prism assembly - Google Patents

Abstract

PURPOSE:To make it possible to drastically decrease the number of stages necessary for forming prisms, to extremely easily execute accurate working and to smoothly form the prism assembly. CONSTITUTION:Optical glass plates 30b formed by simultaneously polishing both front and rear surfaces of optical glass plates having a square planar shape and respectively forming polarizing films 31 and reflection films 32 on both surfaces and optical glass plates 30b which are not formed with these films are superposed stepwise and adhered to each other to form the glass plate laminate in such a manner that the polarizing films 31 and the reflection films 32 are successively formed on the respective superposed joint surfaces. The laminate is cut diagonally at 45 deg. angle with the superposed surfaces at every prescribed interval. Both cut surfaces are simultaneously polished, by which the joined prism constituting body provided with the coating layers inclined at 45 deg. with the polished surfaces is formed. The joined prism constituting body is cut at every position including the polarizing films 31 and the reflection films 32, by which the square bar-shaped prism body is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a prism assembly in which prisms having different shapes are joined.

[0002]

2. Description of the Related Art As a prism which is a kind of optical element, a prism assembly having two different prisms joined to each other is conventionally known, for example. Reference numeral 1 denotes a prism assembly. The prism assembly 1 is formed by joining a parallelogram prism 2 and a triangular prism 3 with a polarizing film 4 interposed on the joint surface, and a parallelogram prism 2 Of the reflection film 5 on the surface facing the optical path of the reflected light from the polarizing film 4 of
Is provided. The prism assembly 1 having such a configuration is incorporated in a differential detection optical pickup of a rewritable optical disc device and is used as an optical element for reading information written on an optical disc.

That is, as shown in FIG. 10, a perpendicular magnetization film 10a is formed on the surface of a substrate 10 of an optical disk, and information is obtained depending on whether the magnetization direction of the perpendicular magnetization film 10a is upward or downward. In order to read this information, the laser light source 11 is used, and the light from the laser light source 11 is made incident on the beam splitter 13 as parallel light by the collimator lens 12. After passing through the reflecting surface 13a of the beam splitter 13, the light is focused on the perpendicular magnetization film 10a by the condenser lens 14. The reflected light from the perpendicular magnetization film 10a is reflected by the beam splitter 13 and then 1 /
The light is guided to the polarizing element 16 via the two-wave plate 15.
Here, the polarizing element 16 is provided with the polarizing film 16a so as to have an angle of 45 ° with respect to the incident light, and the light incident on the polarizing element 16 depends on the vibration direction by the polarizing film 16a. Thus, for example, the P polarized light component is transmitted through the polarizing film 16a, and the S polarized light component is reflected by the polarizing film 16a.

The laser light applied to the perpendicular magnetization film 10a is
A magneto-optical phenomenon called the so-called Kerr effect occurs depending on the direction of the magnetization, and the plane of polarization of the reflected light slightly rotates left or right depending on the direction of the magnetization. Therefore, there is a difference in the amount of light between the P-polarized component and the S-polarized component depending on the direction of magnetization. Therefore, the output portion of the P-polarized component of the polarizing element 16 and S
A photodetector 17 is provided for each of the polarization component output section and the output section.
a and 17b are provided, both polarization component lights are received, and the comparator 18 detects the light amount difference between the lights of both polarization components. The output of the comparator 18 is used to detect the information written on the optical disc. Reading is performed.

When the polarizing element 16 having the above-mentioned structure is used, the photodetectors 17a and 17b have an output angle of 90 ° between the P-polarized component light and the S-polarized component light. Must also have an angle of 90 °. For this reason, the structure of the optical pickup becomes large. Therefore, when the prism assembly 1 having the structure shown in FIG. 9 is used, the light reflected by the polarizing film 4 is reflected again by the reflecting film 5 and the polarizing film 3
Since it is in a direction parallel to the transmitted light, it is possible to arrange a pair of photodetectors on the same plane, which is convenient because the optical pickup can be downsized.

In the prior art, therefore, the prism assembly 1 is formed by using the rectangular glass material 20 and the triangular glass material 21 each formed into a rod shape by molding means or the like. Here, although it is necessary to grind each surface of these glass materials 20 and 21, the grinding is performed individually.

As shown in FIG. 11, the rectangular glass material 20 has its four faces 20a, 20b, 20c, 20d polished. The upper and lower surfaces 20a, 20b are ground so that they are horizontal, and the left and right surfaces 20c, 20d are ground until they are inclined by a predetermined angle with respect to the upper and lower surfaces 20a, 20b. The jigs 22a to 22d are used to polish the surfaces 20a to 20d. The jigs 22a and 22b have the same structure, and the jigs 22c and 22d may be different, but the jigs 22a and 22b may have the same structure. . First, the jig 22a is provided with a surface 20b of the glass material 20.
Is pasted with an adhesive to polish the surface 20a, and after the processing is finished, the adhesive is peeled off, the surface 20a is adhered to the jig 22b, and the polishing is further performed.
The surface 20d is attached to c, the surface 22c is polished, and then the surface 20c is bonded to the jig 22d to process the surface 22d.

On the other hand, the three surfaces 21a, 21 of the glass material 21
b and 21c are also polished, and therefore jigs 23a to 23c suitable for polishing each surface are used as shown in FIG. The same jigs 23b and 23c can be used, and one of the three surfaces forming the glass material 21, that is, the surface 21c, is not used as a prism surface. The processing of 21c is not an essential requirement.

By polishing the glass materials 20 and 21 as described above, rod-shaped parallelogram prism constituents 24 and triangular prism constituents 25 are formed, and the inclined surfaces of the parallelogram prism constituents 24 are formed. Part 2
A parallelogram prism structure is formed by forming a reflecting film 5 on 4c and a polarizing film 4 on the inclined surface portion 24d (the polarizing film 4 may be formed on the surface 25a side of the triangular prism 25). The prism assembly 1 is formed by bonding 24 and the triangular prism structure 25 such that the surfaces on which the polarization plane 4 is formed are adhered and cut to a desired length.

[0010]

By the way, in order to manufacture the prism assembly 1 by the above-mentioned method, at least four sides are formed on the parallelogram prism side and two sides are formed on the triangular prism side.
The surface must be polished, and each time these surfaces are polished, it is necessary to attach to and remove from the jig, making the manufacturing process extremely complicated. In addition, it is difficult to automate the process. Moreover, since the opposite surface side is adhered to the jig during polishing, the thickness of the adhesive applied between the jig and the glass material is uneven. Then, the surface processing accuracy varies. Therefore, if the thickness of the adhesive is not strictly controlled when the adhesive is applied, there is also a problem that the polishing accuracy is lowered.
Further, when it is used as an optical element incorporated in an optical pickup, it is necessary to make the prism as small as possible, but depending on the above-mentioned method, there is a limit to the miniaturization of the manufactured prism. There are also points.

The present invention has been made in view of the above points, and it is an object of the present invention to easily and highly accurately manufacture a prism assembly in which prisms having different shapes are joined, and it is extremely advantageous. A small prism assembly should be manufactured smoothly.

[0012]

In order to achieve the above-mentioned object, according to the present invention, an optical glass plate, in which both front and back surfaces are simultaneously polished, and the required surfaces of the polished surfaces are coated with coating layers, respectively. The glass plates are laminated by interposing them one by one, and the respective lamination surfaces are fixed with an adhesive to form a glass plate laminate, and the glass plate laminate is formed on the lamination surfaces at predetermined intervals. On the other hand, by obliquely cutting at a predetermined angle and polishing both cut surfaces at the same time, a junction prism structure in which the coating layer is inclined by a predetermined angle with respect to the polishing surface is formed. A prismatic rod-shaped prism body is formed by cutting the prism structure at each position including two coating layers, and the prismatic rod-shaped prism body is cut at predetermined intervals. It is an its features and.

[0013]

The optical glass plate is used as a material for forming the prism assembly. For this optical glass plate,
Use a square one with a certain thickness,
For example, polishing is performed at the same time by lapping. Prepare the optical glass plates formed in this way on one side, or on both sides for half of the optical glass plates and leave the remaining half of the optical glass plates uncoated. To do. Here, various coatings are used, and as described above, when used as an optical element of an optical pickup, the coating layer is composed of a polarizing film and a reflecting film. Therefore, in the following description, it is assumed that the polarizing film and the reflecting film are formed.

An optical glass plate laminate is formed by laminating and bonding a plurality of optical glass plates.
In this optical glass plate laminate, polarizing films and reflective films are alternately interposed between the laminated optical glass plates. For this purpose, for example, a polarizing film is formed on one surface of half of the optical glass plates and a reflecting film is formed on the opposite surface thereof, and thus the optical glass plates coated on both sides and the uncoated optical glass plate are formed. The plates may be laminated so that they are alternately combined. Further, the optical glass plates can be laminated so that they are completely overlapped with each other, but when the triangular prisms forming the prism assembly are formed into the shape of an isosceles right triangle, the optical glass plates are displaced by the thickness of one sheet. As described above, it is preferable to stack the layers stepwise from the viewpoint of improving the yield.

The optical glass plate laminated body formed as described above is cut at a predetermined angle with respect to the overlapping surface thereof, and at an angle of 45 ° when the triangular prism is an isosceles right triangle, and wrapping is performed. Both cutting surfaces are simultaneously polished by processing or the like. This forms a cemented prism structure.

By cutting this bonded prism structure perpendicularly to the surface to be polished and at each position including one pair of the polarizing film and the reflecting film, a rectangular prismatic rod-shaped prism is formed. . In this prism body, a parallelogram prism and a triangular prism are joined by themselves, a polarizing film is interposed on the joining surface, and a reflecting film is provided on the surface of the parallelogram prism facing the polarizing film forming surface. It becomes a prism assembly. Therefore, the product is obtained by cutting this prism body to a desired length. Since the triangular portion facing the reflective film does not function as a prism, this portion may be peeled off and removed as necessary.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, as a material for forming the prism assembly, as shown in FIG. 1, an optical glass plate 30 formed in a rectangular plate shape is used. This optical glass plate 30
For example, the front and back surfaces are simultaneously polished by the lapping device shown in FIGS. 2 and 3. In the figure, reference numeral 40 denotes a lapping machine in the lapping apparatus, and the lapping machine 40 includes an inner gear 41 and an outer gear 42.
And the upper and lower turntables 43 and 44, and the lower surface of the upper turntable 43 and the upper surface of the lower turntable 44 are polishing surfaces for polishing the surface of the optical glass plate 30. Between the turntables 43 and 44,
A carrier 45 having a gear that meshes with the inner gear 41 and the outer gear 42 is interposed. The carrier 45 is provided with a plurality of work mounting openings 45a in which the optical glass plate 30 is mounted. The optical glass plate 30 is attached to the work attachment opening 45a of the carrier 45,
Turntable 4 on both the front and back of this optical glass plate 30.
Both turntables 4 while being held between 3,44
By rotating 3, 44 in the opposite direction, the carrier 45 revolves around its own axis as indicated by the arrow in FIG. 2, and as a result, the optical glass plate 30 mounted on the carrier 45 is Both the front and back surfaces are polished at the same time, and the front and back surfaces are mirror-finished.

As indicated by the phantom line in FIG. 1, when the surface of the optical glass plate 30 is polished, half of them are left as they are, that is, the non-film-forming optical glass 30a,
The remaining half of the optical glass plates 30 are, as shown in FIG. 4, formed with a polarizing film 31 on one surface and a reflecting film 32 on the other surface by means such as vacuum deposition. No optical glass plate 30b, and these film-formed optical glass plates 30b
And the same number of non-film-forming optical glasses 30a are prepared.

Next, the film-forming optical glass plates 30b and the non-film-forming optical glass 30a are alternately superposed and the superposed surfaces are adhered with an adhesive to bond the glass as shown in FIG. The plate stack 50 is formed. Therefore, as shown in the enlarged view of FIG. 6, the glass plate laminated body 50 has an optical glass plate 30a having an optical glass plate 30a, an adhesive layer 51, a polarizing film 31 and a reflective film 32 formed on both sides, and an adhesive. The layer 51 and the optical glass plate 30a are laminated in this order. Here, the film-forming optical glass plate 30b and the non-film-forming optical glass 30a can be laminated so as to completely overlap each other.
It is advantageous to improve the yield of products that the glass plate laminate 50 is formed in a stepwise manner by sequentially laminating the glass plates by shifting the thickness of the sheets.

Next, the glass plate laminate 50 is cut in a direction at an angle of 45 ° with respect to the overlapping surface, as shown by the dotted line in FIG. This cutting can be performed almost accurately by using a band saw or the like while adjusting the angle by the angle detecting means or the like. As a result, as shown in FIG. 7, a quadrangular plate-shaped cemented prism structure 60 is formed. Then, the cemented prism structure 60 is mirror-finished by simultaneously polishing both the front and back surfaces thereof using a device similar to a lapping device for polishing the optical glass plate 30.

Further, the cemented prism structure 60 is
As shown by the dotted line in FIG. 7, the cutting is performed in a direction perpendicular to the surface thereof and so as to include the polarizing film 31 and the reflecting film 32. As a result, a long rectangular rod-shaped prism body 70 is formed as shown in FIG. Then, the prism assembly 80 is formed by cutting the rectangular rod-shaped prism body 70 into a desired length. The prism assembly 80 is a cemented prism of a parallelogram prism 81 and a triangular prism 82, and a polarizing film 31 is interposed between the prism 81 and the cemented surfaces of the prisms 81, 82. A reflection film 32 is formed on the surface opposite to the surface on which 31 is formed, and the structure is substantially the same as that of the prism assembly 1. The prism assembly 80 includes a parallelogram prism 81 and a triangular prism 82, and a triangular glass portion 83 is provided on the side where the reflective film 32 is formed. The glass portion 83 functions as a prism. It does not. Therefore, in order to reduce the size of the prism assembly 80, the glass portion 83 can be removed.

After forming the prism assembly 80,
In order to remove the glass portion 83, for example, a reflective film of the non-film-forming optical glass 30a is used as an adhesive when forming the glass plate laminate 50 including the film-forming optical glass plate 30b and the non-film-forming optical glass 30a. The surface to be superposed on 32 is adhered using a peelable adhesive which can be easily exfoliated by a solvent such as a water-soluble adhesive, and the surface to be superposed on the polarizing film 31 is adhered to the surface. A stable, non-peeling adhesive such as an epoxy-based adhesive is used to form the prismatic rod-shaped prism body 70, and then the water-soluble adhesive is melted to form the glass portion 83. The corresponding part may be peeled off.

As described above, the prism assembly 80
If you manufacture, compared to conventional manufacturing man-hours,
Since it is extremely small, it can be easily manufactured.
In particular, it is difficult to automate and eliminates the process of attaching and peeling to a jig made of glass material that requires manual work.
Since both sides are simultaneously polished by the lapping device, automation of the manufacturing process is promoted. Also,
Compared to the case where surface polishing is performed with the glass material attached to the jig with an adhesive, double-sided simultaneous polishing is performed using a lapping machine, so it is extremely easy and highly accurate. A polishing process can be performed. Moreover, the polishing process is performed at the stage of the optical glass plate 30 formed in the shape of a rectangular plate and at the stage of the joint rhythm component 60 which is also cut in the shape of a rectangular plate, and these are processed by the lapping device. Since it is a plate-like material suitable for simultaneous double-side polishing, surface polishing can be performed with high precision and efficiency. Thereafter, the cemented prism structure 60 is cut to form a prismatic rod-shaped prism body 70, and the prismatic rod-shaped prism body 70 is cut to form a prism assembly 80. It is not necessary to finish these surfaces after cutting because they are not the surfaces that enter, exit, or reflect. As described above, since the polishing process is not required at the stage of the prismatic rod-shaped prism body 70 and the prism assembly 80 which are difficult to polish by the lapping device, the prism assembly 80 as a product is 1 cm square or less. It is possible to easily and efficiently manufacture a product having an extremely small shape and good optical accuracy.

In the above-mentioned embodiments, the coating layer formed on the prism is a polarizing film and a reflecting film, but this is for use as an optical element for an optical pickup. It suffices as long as it is a junction prism of a parallelogram prism and a triangular prism, and an appropriate coating layer is applied depending on the application of the prism assembly. As means for performing double-sided polishing, various lapping devices other than the lapping machine shown in FIGS. 2 and 3 can be used, and the upper and lower turntables do not necessarily have to rotate in opposite directions. . Furthermore, after polishing the optical glass plate 30, half of the glass plates are coated with the coating layers on both sides, but it is also possible to form the coating layer on one side of all of them. It is not limited to vacuum deposition.

[0025]

As described above, according to the present invention, the front and back surfaces are simultaneously polished, and the optical glass plates coated with the required surfaces of the polished surfaces are provided with one coating layer between each. In this way, a glass plate laminated body is formed by adhering each laminated surface with an adhesive, and the glass plate laminated body is inclined at a predetermined angle with respect to the laminated surface at predetermined intervals. By cutting the both sides, and performing simultaneous polishing on both sides of the cut surface, to form a bonded prism structure in which the coating layer is inclined by a predetermined angle with respect to the polishing surface,
This junction prism structure is cut at each position including two coating layers to form a prismatic rod-shaped prism body, and the prismatic rod-shaped prism body is cut at predetermined intervals. The number of steps required for forming can be significantly reduced and automation can be performed. Especially, the surface polishing process is not performed in a state where it is attached to a jig, but both sides are simultaneously processed by using a lapping device. Since it can be polished, it can be processed automatically, efficiently, and extremely easily, and the processing accuracy becomes extremely good.
Further, the prism assembly having an extremely small shape can be smoothly formed.

[Brief description of drawings]

FIG. 1 is a side view of an optical glass plate as a member constituting a prism assembly of the present invention.

FIG. 2 is a plan view showing a lapping machine for performing a polishing process, in which an upper turntable is removed.

FIG. 3 is a half sectional view of a lapping machine.

FIG. 4 is a side view of a film-forming optical glass plate.

FIG. 5 is an external view of a glass plate laminate.

FIG. 6 is a cross-sectional view showing an enlarged part of the glass plate laminate.

FIG. 7 is a side view of the cemented prism structure.

FIG. 8 is an external view of a rectangular rod prism body.

FIG. 9 is a structural explanatory view of a prism assembly.

FIG. 10 is a structural explanatory diagram of a differential detection optical pickup in a rewritable optical disc device.

FIG. 11 is an explanatory diagram showing a forming process of a parallelogram prism according to a conventional technique.

FIG. 12 is an explanatory diagram showing a process of forming a triangular prism according to a conventional technique.

[Explanation of symbols]

 30 Optical glass plate 30a Non-film-forming optical glass plate 30b Film-forming optical glass plate 31 Polarizing film 32 Reflective film 40 Lapping machine 50 Glass plate laminated body 51 Optical glass plate 60 Bonding prism structure 70 Square rod prism body 80 Prism assembly 81 Parallelogram prism 82 Triangular prism

Claims (4)

[Claims] 1. An optical glass plate having both front and back surfaces polished at the same time, and a desired surface of the polished surface is coated with optical glass plates such that one coating layer is interposed between the optical glass plates. A glass plate laminate is formed by fixing the surfaces with an adhesive, and the glass plate laminate is obliquely cut at a predetermined angle with respect to the overlapping surface at predetermined intervals, and both cut surfaces are simultaneously cut. By polishing, to form a cemented prism structure in which the coating layer is inclined at a predetermined angle with respect to the polished surface, and to cut the cemented prism structure at two positions including the coating layer. A prismatic rod-shaped prism body is formed by, and the prismatic rod-shaped prism body is cut at predetermined intervals. 2. The manufacturing method of a prism assembly according to claim 1, wherein the optical glass plates are stacked in a step-like manner by shifting by the same angle as the cutting angle of the optical glass plate laminate. Method. 3. The coating layer comprises a polarizing film and a reflecting film, and the polarizing film and the reflecting film are alternately arranged between the optical glass plates facing each other. Of manufacturing a prism assembly of. 4. The adhesive on the bonding surface on the reflection film forming side is a peelable adhesive, and the adhesive on the bonding surface on the polarizing film forming side is a non-peeling adhesive. 4. The method of manufacturing a prism assembly according to claim 3, wherein the peelable adhesive is peeled off after the mold rod prism body is formed.