JPH07110961A - Bonded prism - Google Patents

Abstract

PURPOSE:To obtain a bonded prism in which the surface of the prism can be coated with a reflecting film, a BS film, a PBS film or the like even at a high temperature after prism have been bonded. CONSTITUTION:When a plurality of prisms 1, 2 are bonded at their optical faces, a fusing glass is used as a bonding agent. Thereby, the surface of the bonded prisms 1, 2 can be coated with various kinds of optical films at a high temperature after the prisms have been bonded, and the function of the bonded prisms 1, 2 can be increased. In addition, the fusing glass is filled into a groove on the bonding face of at least one out of the prisms 1, 2 and the prism is made to function as an optical element after the fusing glass has been solidified. Thereby, the function of the bonded prisms 1, 2 can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in various optical devices, optical waveguide coupling / branching devices, optical disks, etc., and particularly relates to bonding of prisms.

[0002]

2. Description of the Related Art Micro prisms used in optical pickups for CDs and MDs have conventionally been used for MO detection (detection of magneto-optically recorded signals: pit information signals for CDs), detection of servo signals (focus servo, tracking). For detection of servo), a cemented prism in which surfaces of a plurality of prisms are bonded together is used. Conventionally, for bonding the prisms, an epoxy resin-based two-component mixed adhesive or an acrylic resin-based UV (ultraviolet) curable adhesive is used in consideration of optical characteristics such as transmittance and refractive index. .

Here, a reflective film on the prism surface or BS
(Beam Splitter) membrane, PBS (Polar)
The coating of the izing BS) film is performed by depositing silicon oxide (SiO ₂ ), cerium oxide (CeO ₂ ) or the like on the glass surface which is the prism base material. For example, as shown in FIG. The prism 17 is attached to the surface of the prism 16 coated with 15 using the above adhesive. However, in the case of coating a BS film or the like on the surface of the bonded prism in which the prisms 16 and 17 are bonded together, generally, the bonded prisms 16 and 17 are heated to a high temperature (3
It is necessary to put it under a temperature of about 00 ° C). Since ordinary synthetic resin adhesives cannot withstand this high temperature, it is very difficult to coat the prism surface after prism bonding with a SiO ₂ , CeO ₂ film or the like, and it is often not done in general.

[0004]

Since a general synthetic resin adhesive cannot withstand a high temperature of about 300 ° C., a reflecting film or a BS film is formed on the prism surface after joining two or more prisms with the synthetic resin adhesive. , PBS film cannot be coated. However, some of them can be coated at a low temperature, but they are not often used because the obtained films have poor durability and weather resistance. Therefore, it is an object of the present invention to provide a cemented prism in which the prism surface can be coated with a reflective film, a BS film, a PBS film or the like even at high temperature after the prism is bonded.

[0005]

The above objects of the present invention can be achieved by the following constitutions. That is, it is a bonding prism that uses fused glass as a bonding agent when bonding the optical surfaces of a plurality of prisms. The cemented prism of the present invention can coat the surface of the cemented prism with an optical film, and can function as an optical element after the fused glass as the cement is solidified. For example, a groove is provided on the bonding surface of at least one prism,
The fusing glass is filled in the groove, and after the fusing glass is solidified, it functions as an optical element.

As the bonding agent of the present invention, a low melting point fused glass is used, but there are about 300 types of low melting point glass having a melting point of about 300 ° C., each of which has its own characteristics. In the present invention, the glass component of the low melting point fused glass and the film components such as the BS film, the PBS film, and the half mirror (HM) film used therefor can be arbitrarily designed at the time of design depending on the prism used in the target optical device. It is set to and is not specified. The HM film is a metal film of silver, aluminum or the like, a metal film HM for depositing an Inconel film or a chromel film, a non-metal film HM of cerium oxide, silicon oxide or magnesium fluoride, a metal film HM and a multi-layer non-metal film HM.
The combination film HM or the like is used. This HM film is coated on the prism by a method such as a vacuum deposition method, a sputtering method, an ion plating method.

Further, the refractive index of the glass used for the prism,
According to the physical properties such as transmittance, or in order to obtain the desired performance, by changing the composition of the constituent components of these fused glass,
The refractive index and the transmittance can be set to desired values. Also,
Bonding film thickness can be controlled by fusing conditions of fused glass. The management of the bonding film thickness is to inject the molten glass into the gap portion of the bonding surface by utilizing the capillary phenomenon and adjust the thickness of the gap portion by the film thickness of the molten glass. Specifically, the fact that the glass viscosity changes in proportion to the temperature and the fact that the fusion time corresponds to the glass inflow distance in the gap part controls the film thickness of the gap part by setting the fusion temperature and time. it can. A glass having a low melting point is used as the fused glass of the present invention.
16 (softening point 463 ° C., density 5.26), 7570 (softening point 440 ° C., density 5.42, refractive index n _d = 1.8
6), 8463 (softening point 377 ° C., density 6.22), etc. or glass type SFS01 (refractive index n _d = 1.9) manufactured by OHARA CORPORATION.
2286, softening point 449 ° C.) and the like are used.

[0008]

By using fused glass as a bonding agent when bonding the optical surfaces of a plurality of prisms, various optical films can be coated on the surfaces of the prisms bonded at high temperature after the prisms are bonded. The function can be enhanced. Further, if the fused glass is filled in the groove of the bonding surface of at least one prism, and if the fused glass has no anisotropy in at least one direction after solidification, the fused fused glass functions as an optical element. It is possible to enhance the function of the cemented prism.

[0009]

Embodiments of the present invention will be described with reference to the drawings. Example 1 FIG. 1 shows an example of a bonded micro prism. Either one of the prism 1 and the prism 2 made of optical glass (BK-7, SF11, etc.) is coated with the HM film 11, and the prism 1 and the prism 2 are joined. The BS film 12 is formed on the prism 3 or the prism 4 made of optical glass.
And the prism 3 and the prism 4 are joined together. The thus obtained joined prisms 1 and 2 and the joined surfaces of the prisms 2 and 3 of the joined prisms 3 and 4 are joined together. Fused glass is used as a bonding agent for the bonding surfaces of the prisms 1 to 4. As described above, the fusion glass having a low melting point has a melting point at the time of vapor deposition of the HM film 11 or the BS film 12 at the time of joining the prisms 1 to 4, and has a refractive index and other characteristics similar to those of the prisms 1 to 4. By bonding, the same coating can be applied to the surface of the prism after the bonding of the prisms 1 to 4 as well as to the surface of a single prism which is not bonded normally. That is, for example, an AR (Anti-Reflection) film or the like can be coated for the purpose of antireflection.

Example 2 This is an example of a bonded micro prism as shown in FIG. Prior to bonding the two prisms 5 and 6,
A groove 6a as shown by a hatched portion is previously formed on the surface of one prism 6 for bonding. Then, the fusing glass 13 used in Example 1 is filled in the groove 6a, and at the same time, the bonding surfaces of the prisms 5 and 6 other than the groove 6a are coated with the fusing glass to bond both prisms 5 and 6. To do. The prisms 5 and 6 used in this embodiment are the prisms 1 to 1 used in the first embodiment.
It is the same as 4. Further, the fused glass 1 in the groove 6a
The cemented prism obtained after 3 is solidified can be used as a modified prism having a different refractive index for a polarizer, a semi-transparent mirror, an interference filter, or a functional component combining these.

Example 3 FIG. 3 shows a laminated microprism of this example.
After the prism 7 and the prism 8 are joined, a groove 8a is provided in the prism 8 so that a cutout can be formed in either of the prisms 7 and 8. Then, the groove 8a is filled with the fused glass 13. The feature of this embodiment is that the prisms 7 and 8 and the fused glass 13 solidified have no anisotropy in at least one direction,
The structure is such that it functions even if it is cut out as a single prism, and the fused and sealed fused glass portion also functions as an optical element. Then, the HM film, the BS film, or the PBS film can be coated on the prisms 7 and 8 including 13 parts of the fused glass. The deformed prism of this embodiment can also be used in applications such as a polarizer, a semitransparent mirror, an interference filter, and functional parts combining these.

According to the above-described embodiment of the present invention, it becomes possible to coat an optical film after two or more prisms are joined, and a film having excellent mass productivity, durability and weather resistance can be applied to the joined prism. It becomes possible to do it. Also,
Since the durability of the bonding agent itself is high, a durable bonded prism can be obtained. In addition, by changing the refractive index of the fused glass, it becomes possible to take measures against stray light, which is a problem with respect to the reflection / splitting / spectral characteristics of the prism when used as a light amount detecting functional component.

[0013]

According to the present invention, it is possible to coat an optical film after the joining prism is joined, and it is possible to form a film having excellent mass productivity, durability and weather resistance on the joining prism. Further, the fused glass can be filled in the groove on the joint surface of the prism, and after the fused glass is solidified, the deformed prism can function as a component of various optical devices.

[Brief description of drawings]

FIG. 1 is a perspective view of a bonded prism according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a bonded prism of Example 2 of the present invention.

FIG. 3 is a perspective view of a bonded prism of Example 3 of the present invention.

FIG. 4 is a perspective view of a bonded prism of the related art.

[Explanation of symbols]

1-8 ... Prism, 11 ... HM film, 12 ... BS film, 13
… Fused glass

Claims (4)

[Claims] 1. A bonded prism, wherein fused glass is used as a bonding agent when bonding optical surfaces of a plurality of prisms. 2. The cemented prism according to claim 1, wherein the surface of the cemented prism is coated with an optical film. 3. The cemented prism according to claim 1, which functions as an optical element after the fused glass as a cement is solidified. 4. A groove portion is provided on a joint surface of at least one prism, and a fused glass that functions as an optical element after solidification is filled in the groove portion.
Alternatively, the junction prism according to item 2.