JPS6331762B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a multi-reflection light interference polarizer, in particular, a multi-reflection light interference polarizer, in particular, a light polarizing filter in which a plurality of types of dielectric thin films are laminated, which are arranged to face each other and prevent undesired total reflection. The present invention relates to a multi-reflection light interference polarizer in which multiple reflection is performed by the above-mentioned light polarization filter to separate P waves and S waves in a light component.

Conventionally, crystals such as calcite have been used as a means of separating the polarized components of light, but it is also known that optical interference filters have the function of separating P-wave components and S-wave components. There is. but,
When the optical interference filter is used as an optical polarization filter, the accuracy of separating the P wave component and the S wave component is insufficient, and it cannot be used where high accuracy of, for example, 50 dB to 60 dB is required.

The present invention aims to solve the above-mentioned problems. For example, by arranging optical polarizing filters on both sides of glass to form multiple reflections, it is possible to obtain high-precision polarization.
The purpose is to separate the wave component and the S-wave component. Therefore, the multiple reflection light interference polarizer of the present invention is a polarizer that is interposed on the path of light containing P-wave components, S-wave components, or both components to separate P-wave components and S-wave components. , a dielectric multilayer film in which multiple types of dielectric thin films are laminated in a multilayer structure is used as an optical polarizing filter, and the refractive index is equal to or greater than the one of the materials used for the polarizing filter. The light polarizing filters are placed opposite to each other with a first substance having a high refractive index sandwiched between them, and a second substance having a high refractive index is appropriately placed on the back side of each of the light polarizing filters to prevent reflection based on undesired total reflection. of the light that is incident on the light polarization filter at a desired angle of incidence through the first substance and has a value larger than that of the S wave component and the P wave component. The reflected light is made to enter the other opposing light polarizing filter at a desired angle of incidence to separate the P wave component and the S wave component.
It is characterized by separating the wave components. This will be explained below with reference to the drawings.

FIG. 1 is an explanatory diagram illustrating the optical polarization filter according to the present invention, FIG. 2 is an embodiment of the configuration of a multiple reflection light interference polarizer according to the present invention, and FIG. FIG. 4, which is an explanatory diagram for explaining problems in a reflected light interference polarizer, shows an application example of the multiple reflected light interference polarizer of the present invention.

In FIG. 1, 1 is a light polarizing filter, 2-
1, 2-2, 2-3, 2-4, . . . represent dielectric layers, respectively. For example, dielectric layers 2-1, 2-
2, . . . have dielectric constants that have a relationship of magnitude, and have a layer thickness of λ/4 with respect to the wavelength of light incident thereon. Such a light polarizing filter 1
As is well known, when the wavelength of light λ is plotted on the horizontal axis, the reflectance decreases rapidly below a certain wavelength, but near this wavelength λ ₀ , the reflectance of the P-wave component and the reflectance of the S-wave component are There are relatively large differences. Furthermore, when the horizontal axis is the incident angle of light incident on the polarizing filter, the reflectance of the S-wave component increases monotonically as the incident angle increases, while the reflectance of the P-wave component increases as the incident angle increases. It has a minimum value when it is near the angle of .

FIG. 2 shows the configuration of an embodiment of the present invention, in which reference numerals 1A and 1B are optical polarization filters corresponding to those in FIG. 1, 3 is a multi-reflection light interference polarizer according to the present invention, and 4 is an atmosphere. , 5 is glass, for example, and has a refractive index higher than atmosphere 4, 6A, 6B
7 is, for example, glass and has a suitably large refractive index so as not to cause total reflection at the interface with the polarizing filter, and 7 is the incident light, which includes, for example, a P-wave component and an S-wave component. Deiramono, 8-1, 8
-2, . . . represent reflected S wave components, 9 represents output S wave components, and 10-1, 10-2, . . . represent transmitted P wave components.

When incident light 7 containing a P-wave component and an S-wave component is incident on the optical polarization filter 1A through the glass 5 at a predetermined angle of incidence, the S-wave component included in the incident light 7 is Mostly reflected S-wave component 8-
1 and is reflected, while P contained in the incident light 7
Most of the wave components are transmitted as P wave components 10-1. Then, the S-wave component 8-1 is incident on the other optical polarization filter 1B, where most of the S-wave component is reflected and becomes the reflected S-wave component 8-2, and the S-wave component 8-1 Most of the P-wave components contained therein are transmitted and become the transmitted P-wave component 10-2 shown in the figure. The same applies below,
Finally, only the S wave component is output as the S wave component 9. Now light polarizing filter 1A or 1
If the separation rate of B is η (η<1), the total separation rate of the results of n reflections is η _o , and the output S wave component 9 contains almost all P wave components. It becomes something that cannot be done.

FIGS. 3A, B, and C are explanatory diagrams for explaining problems in the multiple reflection light interference polarizer of the present invention, and symbols 1A, 4, 5, and 6A in the figures correspond to FIG. 2,
11 represents incident light, and 12 represents output light.

The multiple reflection light interference polarizer 3 of the present invention has the function of separating the P wave component and the S wave component as explained with reference to FIG. When the incident light 11 directly enters the light polarizing filter 1A from 4, the refraction angle ₀ becomes smaller than the incident angle i, and when the angle ₀ becomes less than the limit, the above separation of the light polarizing filter 1A A significant decline in function occurs. Further, as shown in FIG. 3B, even when a glass 5 having a refractive index higher than that of the atmosphere 4 is provided and the light is incident on the polarizing filter 1A, the back surface of the polarizing filter 1A is exposed to the atmosphere 4 having a small refractive index. If it is exposed, as is well known, total internal reflection will occur and the P will be separated.
Wave components will be reflected undesirably. Furthermore, even if the polarizing filter 1A is lined with a glass 6A having a high refractive index as shown in FIG. 3C,
As shown in FIG. 3C, there is a risk that total reflection will occur on the surface PL of the glass 6A, so care must be taken.

FIG. 4 shows one application example using the multiple reflection light interference polarizer of the present invention. Code 1A in the figure,
1B corresponds to FIG. 2, 3A and 3B are multiple reflection light interference polarizers corresponding to FIG. 2, 13 is a laser beam having an S wave component, 14 is the output light of the polarizer 3A,
15 is the input light of the polarizer 3B, 16 is the output light of the polarizer 3B, 17 is the undesired interference light, 18 is the output light from the polarizer 3B in the interference light, and 19 is the output light for the polarizer 3A. 20-1, 20-2, . . . and 21-1, 21-2, . . . are transmitted lights, and 22 and 23 are light control means such as a Faraday rotator or a light beam plate, which are shown on the left in the figure. The light passing from the right to the right passes through without being illuminated, and the light passing from the right to the left in the figure represents that which is illuminated at 90 degrees.

One major problem in devices using laser light 13 with a high purity S-wave component is that unwanted interference light 17 interferes with laser light 13. In the case shown in FIG. 4, the laser beam 13 is multiple-reflected as explained with reference to FIG.
is output as follows. Then, the light becomes the input light of the polarizer 3B without being applied by the light control means, and is subjected to multiple reflections as described above to become the output light 16. On the other hand, even if the interference input light 17 as shown in the figure exists, the interference input light 17 is entirely transmitted and does not interfere with the laser beam 13 as described below. That is, the interference input light 17 is P
Even if it contains a wave component and an S wave component, the P wave component is transmitted by the polarizer 3B as the transmitted light 20-1, 20
-2,... and is transmitted. and S
The output light 18 consisting only of wave components is transmitted to the light control means 2.
2 and 23, the light is applied at 90 degrees to become P-wave component light, which becomes interference input light 19 and is input to the polarizer 3A. Then, the P-wave component interference input light 19 passes through the polarizer 3A as transmitted light 21-1, 21-2, . . .
...and it becomes transparent. That is, the laser beam 13
There will be no interference with the

As described above, according to the present invention, it is possible to separate the P wave component and/or the S wave component with high precision using an optical polarizing filter, which has conventionally had a poor separation rate.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the optical polarization filter according to the present invention, FIG. 2 is an embodiment of the configuration of a multiple reflection light interference polarizer according to the present invention, and FIG. FIG. 4, which is an explanatory diagram for explaining problems in a reflected light interference polarizer, shows an application example of the multiple reflected light interference polarizer of the present invention. In the figure, 1, 1A, 1B are optical polarizing filters, 2-
1, 2-2, ... are dielectric layers, 3, 3A, 3, respectively.
B, is a multiple reflected light interference polarizer, 4 is the atmosphere, 5 is glass, 6A and 6B are each glass, 7 is incident light,
8-1, 8-2, ... are the reflected S-wave components, 9 is the output S-wave component, 10-1, 10-
2, . . . represent transmitted P-wave components, and 22 represents a light control means.

Claims (1)

[Claims] 1 In a polarizer that separates P-wave components and S-wave components by intervening on the path of light containing P-wave components, S-wave components, or both components, multiple types of dielectric thin films are laminated in a multilayer structure. The dielectric multilayer film is configured to be used as an optical polarizing filter, and the above-mentioned light is sandwiched between a first substance having a refractive index equal to or larger than the smaller refractive index of the material used for the polarizing filter. The polarizing filters are arranged to face each other, and a second substance having a suitably large refractive index is placed on the back surface of each of the optical polarizing filters to prevent reflection based on undesired total internal reflection,
The S-wave component of the light incident on the light polarization filter at a desired angle of incidence through the first substance is reflected with a larger value than the P-wave component, and Multi-reflected light interference polarization characterized in that the reflected light is made to enter the other opposing light polarizing filter at a desired angle of incidence to separate the P wave component and the S wave component. vessel.