JPH03175437A - polarization analyzer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of a polarization analyzer.

[Prior art] - A method for polarizing and analyzing light in a projection display device using a conventional reflective liquid crystal light valve is disclosed in Japanese Patent Publication No. 1986-517.
4, a method using a polarizing beam splitter capable of polarizing light over the entire visible range has been common.

[Problems to be Solved by the Invention] However, with the above-mentioned technology, the polarization characteristics of the polarizing beam splitter depend on the angle of incidence of the light rays, so if the incident light is not completely parallel light, the polarization rate decreases and the polarization Since the polarization ratio of the beam splitter has wavelength dependence, there is a problem that the contrast of the projected image becomes low.

The present invention is intended to solve these problems, and its purpose is to improve the polarization rate of a polarization analyzer in a projection display device using reflective liquid crystal light pulp, and to improve the contrast of projected images. The goal is to increase the

[Means for Solving the Problems] The polarization analyzer of the present invention includes a polarizing beam splitter in which the slopes of a pair of right-angled prisms are bonded to each other, and a dielectric multilayer film is provided on the bonded surfaces; It is characterized by comprising two polarizers arranged so that two branched linearly polarized lights having mutually orthogonal polarization planes are transmitted, respectively.

[Example] (Example 1) FIG. 1 is a diagram showing the structure and operation of a polarizing beam splitter used in Example 1. As shown in the figure, it has a structure in which the slopes of a pair of right angle prisms 12 are glued together and a dielectric multilayer coating layer 15 is formed on the bonded surface. P-polarized light contained in 11 is transmitted, and S-polarized light is reflected and bent by 90°.

Figure 2 shows how r1 has polarization over the entire visible range.
This is a diagram showing an example of the transmittance-wavelength characteristics of the manufactured polarizing beam splitter. In this polarizing beam splitter, S-polarized light is mixed into the transmitted light in the entire visible range, and the polarization rate has wavelength dependence. . Furthermore, when the angle of incident light changes, the polarization rate decreases.

FIG. 3 is a diagram showing the configuration of a polarization analyzer according to the present invention. One polarizing beam splitter 51 and incident light 64
The polarizer 55 is arranged so that only the P-polarized light passes through the P-polarized light emitting part of the light incident from the direction, and the polarizer 52 is arranged so that only the S-polarized light passes through the S-polarized light emitting part. Each polarizer is arranged in close contact with or spaced apart from the polarizing beam splitter.

For the incident light 54, it acts as a polarization splitter that separates the PS polarized light with an angle of 90 degrees to each other, and for the incident light 55, it acts as a polarizer that bends only the S polarized light by 90 degrees and extracts it. It acts as a polarizer that transmits and extracts only P-polarized light.

FIG. 4 is a plan view of the configuration of Embodiment 1, and the polarization analyzer of the present invention includes a polarization beam splitter 405 that has polarization properties for all visible light, and polarizers 402 and 409 (polarizing plates, polarizing prisms, etc.). , prepolarizer, etc.). Light source lamp 401 with a parabolic reflector
The almost parallel light ray α emitted from a halogen lamp, metal halide lamp, xenon lamp, etc. passes through a polarization analyzer and only P-polarized light is extracted. light (h), red light (C), green light (
d) separated. Each light beam modulated by the reflective liquid crystal light valve follows the same path in reverse and enters the polarization analyzer, and only the S-polarized light is extracted and enters the projection lens 410, where an image is formed on the screen 411.

(Example 2) FIG. 5 is a perspective view of the configuration in Example 2 of the present invention. The almost parallel light rays emitted from the light source lamp 501 are
The three primary colors are separated by a cube prism 502 and bent by 90 degrees by mirrors 505, 504, and 505, and each is connected to a red polarization analyzer 506. Green polarization analyzer 507. The light enters a blue polarization analyzer 508. From the incident light beam, only the S-polarized light is extracted and bent by 90 degrees, and from the light modulated by the reflective liquid crystal light valves 509, 510, and 511, only the P-polarized light is extracted and enters the cube prism 512, where the colors are combined and sent to the projection lens. 513, a color image is formed on a screen 514.

[Effects of the Invention] As described above, according to the present invention, a polarization analyzer having a configuration in which a polarization beam splitter is combined with a polarizer can be used as a polarization analyzer in a projection display device using a reflective liquid crystal light valve. By using this method, it is possible to improve the decrease in the polarization rate caused by the fact that the incident light from the light source is not perfectly parallel light, and to improve the polarization imperfection in existing polarizing beam splitters, that is, to reduce the polarization of the separated P-polarized light. It has the effect of preventing the mixing of S-polarized light and the mixing of P-polarized light with S-polarized light, improving the contrast of the projected image.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration and operation of a polarizing beam splitter. FIG. 2 shows the transmittance-wavelength characteristics of a polarizing beam splitter having polarization over the entire visible range, and FIG. 5 shows the configuration of a polarizing analyzer according to the present invention. FIG. 4 is a plan view of the configuration showing the first embodiment of the present invention. FIG. 5 is a perspective view of the configuration showing the second embodiment of the present invention. Incident light. Right angle prism・・・・・・Dielectric multilayer film・・・・・・Polarizing beam splinter・・・・・・Polarizer ivy

Claims (1)

[Claims] A polarizing beam splitter in which the slopes of a pair of rectangular prisms are glued together and has a dielectric multilayer film on the bonding surface, and two polarizing beam splitters having mutually orthogonal polarization planes separated by the bonding surface.
two linearly polarized lights arranged so that each of them is transmitted through the two
A polarization analyzer characterized by comprising two polarizers.