JPS61145503A - Prism for optical splitting and mixing - Google Patents

Abstract

PURPOSE:To maintain reflection characteristics of a total reflecting surface with inexpensive constitution by providing two prism parts with two opposite plane parts in one body. CONSTITUTION:A light transmission 3 consists of the plane parts 3a and 3b facing the prism parts 1 and 2 and a polarizing and splitting film 4 which has smaller area than the surface facing the prism part 2. The S polarized light of incident light 5 is reflected as projection light 7 and the P polarized light is transmitted through the film 4 as projection light 8; and the incident light 6 becomes projection light beams 8 and 7 similarly. The plane parts 3a and 3b are formed in one body, so even if an adhesive is forced out when the plane part 3a is adhered to the prism part 1e, there is no influence exerted upon the total reflecting surface 3c. Reflection characteristics of the reflecting surface 3c are therefore maintained and the cost is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides first and second
The present invention relates to a light separation/combination prism that combines or separates light having different polarization characteristics, and can be used for optical switches and the like.

[Conventional technology]

A configuration shown in FIG. 5 or 6 is known as a prism for separating and combining polarized light. In FIG. 5, between the first prism section 21 and the second prism section 22,
They are joined together with a light transmitting plate 23 provided with a polarization separation film 24 and a total reflection film 25 interposed therebetween, and the incident light 26 to the first prism section 21 is totally reflected at the interface with the air and is polarized and separated. The light is incident on the film 24, and by this polarization separation film 24, for example, P-polarized light is transmitted and S-polarized light is reflected. The reflected S-polarized light is reflected by the total reflection film 25 and becomes output light 28 from the second prism section 22, and the transmitted P-polarized light becomes output light 29 from the second prism section 22. paternal line 2
The incident light 27 to the prism section 22 is incident on the polarization separation film 24, and the P polarized light is transmitted and the S polarized light is reflected.
The P-polarized light is reflected by the total reflection film 25 and becomes output light 28, and the S-polarized light becomes output light 29.

As mentioned above, each polarization of the incident light 26,27 results in an output light 28.
．． The polarized light is separated as 29. On the contrary, the output light 28.2
When each polarized light is made incident from the output position 9, a combined light is output to the position of the incident light 26 and the incident light 27, and polarized light can be combined.

Also, in FIG. 6, a light transmitting plate 3 is provided with a polarization separating film 34 between the first prism part 31 and the second prism part 32.
This light-transmitting plate 33
The first prism portion 31 is bonded to only a portion of the light-transmitting plate 33, and the portion 35 of the light-transmitting plate 33 is configured to perform total reflection at the interface with air. That is, instead of the total reflection film 25 in FIG. 5, a total reflection surface at the interface with air is used. Thereby, each polarization of the incident light 36°37 becomes an output light 38.39.

FIG. 7 is a schematic perspective view of the above-mentioned transparent plate 33, and FIG.
A polarized light separation film 34 having an area smaller than the opposing surface of the prism part 32 is provided, and the second prism part 32 is bonded to this polarized light separation film 34 side.

[Problem that the invention seeks to solve]

In the conventional example shown in FIG. 5, a metal film or a dielectric multilayer film is used as the total reflection film 25, but the metal film has a reflectance of about 90%, so it is not sufficient, and the dielectric film In order to obtain a high reflectance, the multilayer film must have, for example, 30 or more layers, so it has the disadvantage that it is not easy to manufacture.

Furthermore, in the conventional example shown in FIG.
1 and the translucent Fi 33, the adhesive may protrude onto the total reflection surface 35, and the protruding adhesive may prevent desired reflection characteristics from being obtained. In particular, when applied to an optical switch, the output light 38.39
It is necessary to make the corner between the beams about 1 mm, so the first
Since the total reflection surface 35 of the light-transmitting plate 33 is formed at a position close to the side surface of the prism portion 31, there is a drawback that reflection characteristics deteriorate due to slight extrusion of the adhesive.

The present invention aims to improve the above-mentioned conventional drawbacks.

[Means for solving problems]

The prism for light separation and synthesis of the present invention is provided with a light-transmitting plate having a polarization separation film having a smaller area than the facing surface of the second prism part between the first prism part and the second prism part,
The light from the first prism part is reflected by the polarization separation film, or the light from the second prism part is transmitted through the polarization separation film, and the light from the part not facing the first prism part is reflected by the polarization separation film. The light-transmitting plate is configured to reflect light at an interface with air, and the light-transmitting plate includes a first flat plate portion facing the first prism portion and a second flat plate facing the second prism portion. This is a stepped translucent plate.

[Effect]

Even if the adhesive protrudes when the first flat plate part of the light-transmitting plate and the first prism part are glued together, the reflection characteristics will be affected because the second flat plate part forming the total reflection surface is not on the same plane. will no longer deteriorate.

Therefore, it is easy to manufacture and can perform desired light separation or photosynthesis.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a side view of an embodiment of the present invention, in which 1 is a first prism section, 2 is a second prism section, 3 is a transparent plate, 3a is a first flat plate section, and 3b is a second prism section. 3C is a total reflection surface formed at the interface of the second flat plate with air, and 4 is a polarization separation film. The light-transmitting plate 3 has a configuration in which a first flat plate part 3a facing the first prism part 1 and a second flat plate part 3b facing the second prism part 2 are integrated. The polarization separation film 4 is formed to have a smaller area than the opposing surface of the prism section 2 .

The incident light 5 to the first prism part 1 is totally reflected at the interface with air and enters the polarization separation film 4 formed on the transparent Fi 3. For example, S-polarized light is reflected and P-polarized light is transmitted. . The reflected S-polarized light is reflected on the total reflection surface 3C of the transparent plate 3 and becomes output light 7 from the second prism section 2. The transmitted P-polarized light becomes output light 8 from the second prism section 2.

The incident light 6 on the prism section 2 of the paternal line 2 is incident on the polarization separation film 4, where the P polarized light is transmitted and the S polarized light is reflected. The transmitted P-polarized light is reflected by the total reflection surface 3c of the transparent plate 3 and becomes output light 7, and the reflected S-polarized light becomes output light 8.

As mentioned above, the light-transmitting plate 3 is an integral part of the first flat plate part 3a and the second flat plate part 3b, and the first flat plate part 3
Even if the adhesive protrudes when bonding a and the first prism portion 1, the bonding surface and the total reflection surface 3c are not on the same plane, so it is formed at the interface between the second flat plate portion 3b and the air. It has no effect on the total reflection surface 3C,
Desired reflection characteristics can be obtained.

FIG. 2 is a perspective view of an embodiment of the transparent plate 3, in which a first flat plate part 3a and a second flat plate part 3b are formed separately, and the first and second flat plate parts 3a, 3b are welded and integrated using glass welding technology. Further, on the flat plate portion 3b, a polarization separation film 4 is provided by vapor deposition or the like on the side opposite to the welded flat plate portion 3a.

FIG. 3 is a perspective view of another embodiment of the transparent plate 3, in which the first flat plate part 3a and the second flat plate part 3b are integrated by polishing or other means from a transparent plate of a predetermined thickness. It was originally formed. Then, a polarization separation film 4 is provided on the second flat plate portion 3b by vapor deposition or the like.

By making the first flat plate part 3a have the same dimensions as the opposing surface of the first prism part 1, it becomes easy to maintain the positional relationship including the polarization separation film 4 etc. with high accuracy during assembly and to adhere it. . In addition, in that case, the total reflection surface 3 due to the adhesive protruding
It is possible to prevent the reflection characteristics of C from being affected.

FIG. 4 is an explanatory diagram when applied to an optical switch, in which a magneto-optic effect element 9 such as YIG is placed between a prism A for light separation and synthesis on the input side and a prism B for light separation and synthesis on the output side. The magnetic field is controlled by the coil 10. The prism A for light separation and combination on the input side has the same configuration as shown in FIG. 1, and the same reference numerals indicate the same parts, and the prism B for light separation and combination on the output side also has the same configuration as shown in FIG. However, the relationship between input light and output light is reversed, and a half-wave plate 19 is provided in the second prism section 12. Further, 11 is a first prism section, 13 is a transparent plate, 14 is a polarization separation film, 15.16 is output light, and 17.18 is input light.

Input light 5 is incident on the first prism section 1, and input light 6
is incident on the second prism section 2, and as described above, the output lights 7 and 8 of each polarization are emitted from the second prism section 2 with a beam interval of about 1 mm, and are incident on the magneto-optic effect element 9. Ru. By applying a magnetic field corresponding to the excitation direction of the coil 10 to the magneto-optic effect element 9, the rotation direction of the polarization plane is controlled by the optical rotation characteristics of the magneto-optic effect element 9, and the output side light from the magneto-optic effect element 9 is controlled. Prism B for separation and synthesis
is input as input light 17.18.

These input lights 17 and 18 pass through a half-wave plate 19 to the second
The light is incident on the prism section 12 of. If the input light 17 is P
When polarized light enters the polarization separation film 14, the P-polarized light is transmitted and becomes the output light 16 from the first prism section 11, and when it is S-polarized light, it is reflected and output to the second prism section 12.
The output light 15 becomes. Furthermore, when the input light 18 is S-polarized light, it is reflected by the total reflection surface of the transparent plate 13 and enters the polarization separation film 14, and the S-polarized light is reflected and becomes output light 16 from the first prism section 11, and becomes P-polarized light. The polarized light is transmitted through the polarization separation film 14,
This becomes the output light 15 of the second blizzard section 12 . That is, when the input light 17 is P-polarized, the input light 6 is output as the output light 16. Furthermore, when the light is S-polarized, the input light 5 is outputted as the output light 15.

Therefore, when a magnetic field is applied to the magneto-optic effect element 9 and the direction of the magnetic field is controlled by the excitation direction of the coil 10, the optical rotation characteristics of the magneto-optic effect element 9 change corresponding to the excitation direction, and the polarization direction changes. do. Therefore, by controlling the direction of the magnetic field applied to the magneto-optic effect element 9, the relationship between the input light 5.6 and the output light 15.16 can be switched as described above. That is, it can constitute an optical switch.

〔Effect of the invention〕

As explained above, the present invention provides a light-transmitting device that is provided with a polarization separation film 4 having a smaller area than the facing surface of the second prism portion 2 between the first prism portion 1 and the second prism portion 2. A plate 3 is provided so that the light from the first prism part 1 is reflected by the polarization separation film 4, or the light from the second prism part 2 is transmitted through the polarization separation film 4, and the light from the first prism part 1 is reflected by the polarization separation film 4. A total reflection surface is formed so as to reflect the light at the interface between the light transmitting plate 3 and the air at a portion of the light transmitting plate 3 that does not face the first prism part l, and , the second prism part 2 and the second flat plate part 3b facing each other are integrated, and the first prism part 1 and the first flat plate part 3a of the transparent plate 3 are bonded with adhesive. When bonded, the adhesive surface and the total reflection surface 3C of the transparent plate 3 are not on the same plane, so even if the adhesive protrudes from the adhesive surface, it will not protrude to the total reflection surface 3C. It becomes possible to maintain the reflection characteristics of the total reflection surface 3C.

By making the facing surfaces of the flat plate part 3a of the paternal line 1 and the first prism part 1 the same shape, alignment at the time of adhesion becomes easy, and there is an advantage that desired light separation/synthesis characteristics can be obtained. Further, the output light 7.8 or 15.16 is transmitted through the transparent plate 3.
By simply specifying the parallelism of 13, the desired direction can be obtained, and the first
A transparent plate 3. is made up of a flat plate part 3a and a second flat plate part 3b.
Since a parallelism of 13 can be easily obtained, there is an advantage that high adhesion accuracy is not required.

Therefore, it is possible to provide an inexpensive prism with stable characteristics for use in light separation and synthesis in various optical systems.

[Brief explanation of drawings]

FIG. 1 is a side view of an embodiment of the present invention, FIGS. 2 and 3 are perspective views of transparent plates of different embodiments of the present invention, and FIG.
The figure is an explanatory diagram when applied to an optical switch, FIGS. 5 and 6 are side views of a conventional prism for separating and combining light, and FIG. 7 is a schematic perspective view of a conventional light-transmitting plate. 1.11 is the first prism part, 2.12 is the second prism part, 3 and 13 are transparent plates, 3a is the first flat plate part, 3b is the second flat plate part, 3C is a total reflection surface, 4.14 is a polarization separation film.

Claims (1)

[Claims] The second prism portion is located between the first prism portion and the second prism portion.
A light transmitting plate is provided with a polarization separation film having a smaller area than the facing surface of the prism part, and the light from the first prism part is reflected by the polarization separation film or the light from the second prism part is reflected by the polarization separation film. In the prism for light separation and synthesis, the light is transmitted through the polarization separating film and reflected at the interface between the light transmitting plate and the air in a portion not facing the first prism portion. A prism for light separation and synthesis, characterized in that a first flat plate part facing the prism part and a second flat plate part facing the second prism part are integrally formed.