JPH11202132A - Polarizing prism and reflection type optical modulating projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the polarizing prism which makes the reflection type optical modulating projector small-sized by shortening the optical path length of its optical system and the reflection type optical modulating projector which uses the polarizing prism. SOLUTION: This prism is formed sandwiching and sticking a thin plate glass 1b between two triangular prisms 1a and 1c made of optical glass. Optical thin films are formed on 1ab and 1bc between the triangular prisms 1a and 1c and thin plate glass 1b and the 1ab between the triangular prism 1a and thin plate glass 1b is given spectral characteristics for transmitted P-polarized light and transmitted and reflected light of S-polarized light. Further, the 1bc between the triangular prism 1c and thin plate glass 1b is given spectral characteristics for transmitted S-polarized light and transmitted and reflected light of P-polarized light. Thus, the polarizing prism having a polarized beam splitter function with the mutually independent spectral characteristics of transmitted light and reflected light for the P-polarized light and S-polarized light is obtained, and consequently the reflection type optical modulating projector is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a polarizing prism for shortening the optical path length of an optical system of a reflection type light modulation projector for downsizing, and a reflection type light modulation projector using the same.

[0002]

2. Description of the Related Art FIG. 10 is a conceptual diagram of an example of an optical system of a conventional reflection type light modulation projector. A light beam from a light source 81 including a lamp 81a and a reflecting mirror 81b is reflected by a dichroic mirror 101 that reflects red light and transmits green and blue light. The red ray reflects S-polarized light and
Red PBS (polarizing beam splitter) that transmits polarized light
The polarization-modulating element 85r for red composed of a reflective LCD or the like modulates the polarization with the P-polarized light that enters and passes through 103r, and the PBS.
Return to 103r. The S-polarized light reflected and modulated by the PBS 103r passes through a dichroic mirror 105 that transmits red light and reflects green and blue light, and is projected on a screen by a projection lens. Similarly, the dichroic mirror 10
The green and blue light beams that pass through 1 enter a dichroic mirror 102 that reflects green light and transmits blue light. The green light reflected by the dichroic mirror 102 is converted to a green PB
The light is modulated by S103g and the polarization modulation element 85g, and reflected by the dichroic mirror 104 and the dichroic mirror 105 that reflect green light and transmit blue light, and the projection lens 1
08. Further, the blue PBS 103b and the polarization modulation element 85b modulate the light of the blue light passing through the dichroic mirror 102, enter the projection lens 108,
The green and blue light beams are projected on the screen to display a color image. However, in the configuration of the optical system of such a reflection type light modulation projector, apart from the PBS, at least 4
Various types of dichroic mirrors are required. As a result, the optical path length between the reflection type light modulation element and the projection lens becomes longer, and a lens with a longer back focus is required.Therefore, it becomes difficult to manufacture a lens having a small aperture ratio, which is disadvantageous in terms of resolution and brightness. Become. Further, there is a problem that the size of the optical system becomes large, so that the size and weight of the projector cannot be reduced.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a polarizing prism for shortening the optical path length of an optical system of a reflection-type light modulation projector and miniaturizing the same, and a reflection prism using the same. It is an object of the present invention to provide a light modulation type projector.

[0004]

SUMMARY OF THE INVENTION In a polarizing prism having a polarizing beam splitter function having a spectral characteristic by forming an optical thin film on a bonding surface of two triangular prism transparent media, optical interference between both surfaces is reduced by the bonding surface. A plate-shaped transparent medium having a parallel plane of sufficient thickness to be avoided is interposed, and one polarized light beam is transmitted between one surface of the plate-shaped transparent medium and the one triangular prism transparent medium and is orthogonal to this. Form an optical thin film that reflects the other polarized light with spectral characteristics,
Forming an optical thin film that transmits the other polarized light and reflects the one polarized light with spectral characteristics between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium, A polarizing prism having a polarizing beam splitter function having spectral characteristics independent of one polarized light and the other polarized light orthogonal to the polarized light is obtained.

[0005] The triangular prism transparent medium and the plate-like medium are made of optical glass of substantially the same quality.

The triangular prism medium is made of optical glass obtained by hollowing out the plate-shaped medium portion, and the optical thin film is formed on both sides of the optical glass at the hollowed-out portion. A liquid having a refractive index substantially equal to that of glass.

The two triangular prism media are divided into two parts by connecting a diagonal in the hollow part of the quadrangular prism with the quadrangular prism formed of a hollow transparent medium and the plate-shaped medium having the optical thin film formed on both surfaces thereof. A hollow triangular prism is formed by filling each hollow portion of the two hollow triangular prisms with a liquid having substantially the same refractive index as the plate-shaped medium.

The optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light, transmits S-polarized light having a predetermined wavelength or more, and transmits S-polarized light having a predetermined wavelength or less. The optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium has the property of reflecting light, transmits S-polarized light, transmits P-polarized light of a predetermined wavelength or less, and P-polarized light of a predetermined wavelength or more. It has the property of reflecting light.

An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits S-polarized light, transmits P-polarized light having a predetermined wavelength or more, and converts P-polarized light having a predetermined wavelength or less. The optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium has a property of reflecting light, transmits P-polarized light, transmits S-polarized light having a predetermined wavelength or less, and transmits S-polarized light having a predetermined wavelength or less. It has the property of reflecting polarized light.

An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits white light (W) of P-polarized light and transmits green and red light (Y) of S-polarized light. The optical thin film having the property of transmitting and reflecting the blue light (B) between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium has S
Transmits white light (W) of polarized light and blue light (B) of P-polarized light
And reflects green and blue light (Y).

An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits S-polarized light white light (W) and transmits P-polarized light green and red light (Y). It has the property of transmitting and reflecting blue light (B), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium is P
S-polarized blue light (B) that transmits polarized white light (W)
And reflects green and blue light (Y).

The optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light white light (W) and S-polarized light red light (R). The optical thin film having the property of reflecting blue and green light (C) and between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium has S
It has the characteristic of transmitting white light (W) of polarized light, transmitting blue and green light (C) of P-polarized light, and reflecting red light (R).

An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits S-polarized light white light (W) and P-polarized light red light (R). The optical thin film having the property of reflecting blue and green light (C) and between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium has P
It has the property of transmitting white light (W) of polarized light, transmitting blue and green light (C) of S-polarized light, and reflecting red light (R).

The optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light white light (W) and S-polarized light red light (R). The optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium has the property of reflecting blue light (B) and transmits white light (W) of S-polarized light and transmits P-polarized light. It has the property of transmitting blue light (B) and reflecting red light (R).

An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits S-polarized light white light (W) and P-polarized light red light (R). The optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium has the property of reflecting blue light (B) and transmits white light (W) of P-polarized light and transmits S-polarized light. It has the property of transmitting blue light (B) and reflecting red light (R).

An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light white light (W) and S-polarized light blue light and red light (M). , And has a characteristic of reflecting green light (G), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium transmits S-polarized light white light (W) and transmits P light. It has the property of transmitting polarized green light (G) and reflecting blue light and red light (M).

An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits S-polarized light white light (W) and P-polarized light blue light and red light (M). And the property of reflecting green light (G) is transmitted through the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium. It has the property of transmitting polarized green light (G) and reflecting blue light and red light (M).

In a reflection type light modulation projector for displaying a color image by modulating a light beam from a light source by a combination of a plurality of reflection type polarization modulation elements and a polarizing prism, and projecting it on a screen by a projection lens. A polarizer that makes P light polarized light, a dichroic mirror that reflects green light of the P polarized light and transmits blue and red light, and a P light that reflects the reflected green light and transmits S polarized light Polarizing beam splitter (PBS)
And a polarization modulation element for green which receives a P-polarized green light reflected by the PBS, modulates the polarization, reflects the reflected light, and reenters the PBS, and a blue light and a red light transmitted through the dichroic mirror. A polarizing prism that reflects P-polarized light, transmits S-polarized light, transmits red P-polarized light, and reflects S-polarized light;
Polarization-modulating element for blue which receives polarized light, modulates and reflects it, and re-enters the same polarizing prism, and receives P-polarized light of red light transmitted through the same polarizing prism, and modulates and reflects the same to reflect the same polarized light. A polarization modulator for red that re-enters the prism, and the S-polarized light of the blue light that re-enters the prism with the same polarization prism is transmitted and analyzed, and the S-polarized light of the red light is reflected and analyzed. A dichroic mirror that detects and emits the green light beam re-entering the PBS with the same PBS, transmits blue and red light emitted from the prism, and reflects the green light emitted from the PBS, and emits the same from the dichroic mirror To be a reflection type light modulation projector having a projection lens for projecting and projecting blue, red and green light rays.

A reflection type light modulation projector for modulating a light beam from a light source with a combination of a plurality of reflection type polarization modulation elements and a polarizing prism and projecting it on a screen with a projection lens to display a color image. A PBS that transmits P-polarized light and reflects S-polarized light, a first polarizing prism that transmits S-polarized green light reflected by the PBS and reflects P-polarized light, And a green polarization modulator that receives and modulates the polarized green light, reflects the reflected green light, and reenters the same polarizing prism, and reflects the blue light of the P-polarized light transmitted through the PBS and transmits the S-polarized light of the blue light. And a second polarizing prism that transmits the red light beam and reflects the P-polarized light of the red light, and receives the P-polarized light of the blue light reflected by the same polarizing prism, modulates and reflects the light, and reenters the same polarizing prism. A polarization modulator for blue, a P-polarized light of red light transmitted through the same polarization prism, polarization-modulated, reflected and re-entered the same polarization prism, and re-entered the same polarization prism Analyze the blue light
The polarized light is transmitted, the red light is detected, the S-polarized light is reflected and emitted, and the green light re-entering the first polarizing prism is reflected and analyzed, and the P-polarized light is emitted. A dichroic mirror that transmits blue and red rays and reflects a green ray, and blue emitted from the dichroic mirror,
It is assumed that the projector is a reflection type light modulation projector provided with a projection lens for projecting red and green light rays.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual plan view of an embodiment of the polarizing prism according to the present invention. The two thin triangular prisms 1a and 1c made of optical glass as a transparent medium are laminated with a thin glass plate 1b as a plate-shaped medium made of optical glass of the same material sandwiched therebetween. The thickness of the thin glass plate 1b is set to a thickness sufficient to avoid optical interference between both surfaces of the bonding surface, that is, a thickness sufficiently large as compared with the wavelength of light. An optical thin film is formed between the triangular prisms 1a and 1c and the thin glass plate 1ab and 1bc by a conventional technique, and one polarized light, for example, P-polarized light is transmitted through the 1ab between the triangular prism 1a and the thin glass plate 1b. Spectral characteristics are imparted to the other polarized light orthogonal to this, for example, transmitted light and reflected light of S-polarized light. In addition, a portion 1bc between the triangular prism 1c and the thin glass plate 1b transmits the other polarized light, for example, S-polarized light, and has a spectral characteristic with respect to the transmitted light and reflected light of one polarized light, for example, P-polarized light orthogonal to the other. To have. In this manner, a polarizing beam splitter function having spectral characteristics of transmitted light and reflected light that is independent of one polarized light, for example, P-polarized light and the other polarized light, for example, S-polarized light, is provided. The polarizing prism 1 can be obtained.

FIG. 2 is a conceptual plan view of another embodiment of the polarizing prism according to the present invention. The triangular prism transparent medium and the plate-like medium can be composed of triangular prism glass and plate glass as described above. The optical thin film may be formed on both surfaces 2ab and 2bc of the glass 2 and the hollow portion 2b may be filled with a liquid 2b having substantially the same refractive index as the optical glass 2. This configuration eliminates the need for optical bonding between optical glasses that requires advanced technology.

FIG. 3 is a conceptual plan view of still another embodiment of the polarizing prism according to the present invention. The triangular prism transparent medium and the plate-shaped medium are made up of a quadrangular prism 3 made of a hollow transparent medium made of sheet glass or the like,
b, 3bc, the thin glass 3b having the optical thin film formed thereon
Interposed. The two hollow triangular prism portions divided by the thin glass plate 3b inside the quadrangular prism 3 are filled with a liquid having substantially the same refractive index as that of the glass plate or the like.

FIG. 4 shows (A) transmission spectral characteristics on one surface of a plate-like medium, (B) transmission spectral characteristics on the other surface of a plate-like medium, and FIG.
(C) Transmission spectral characteristics of the polarizing prism as a whole. Here, T represents the light transmittance. For example, the sheet glass 1 of FIG.
b, the white light Lp of the P-polarized light Lp
w, and reflects the blue light Lsb of the S-polarized light Ls
It has a property of transmitting the green light G and the red light R of the polarized light Ls, that is, the yellow light (Y). On the other surface 1bc of the plate glass 1b, the white light Lsw of the S-polarized light Ls is transmitted, and P
It has a characteristic of transmitting the blue light Lpb of the polarized light Lp and reflecting the green light G and the red light R of the P-polarized light Lp, that is, the yellow light (Y). By doing so, the P-polarized light L
p transmits blue light B and reflects green light G and red light R, that is, yellow light (Y). S-polarized light Ls reflects blue light B, and green light G and red light R, that is, yellow light (Y). ) Can be obtained. Similarly, a polarizing prism in which the spectral characteristics of the polarizing prism and the P-polarized light and the S-polarized light are reversed can be obtained.

FIG. 5 shows (A) transmission spectral characteristics on one surface of a plate-like medium, (B) transmission spectral characteristics on the other surface of a plate-like medium, and FIG.
(C) Transmission spectral characteristics of the polarizing prism as a whole. Again, T represents the light transmittance. Similarly to the above, for example, on one surface 1ab of the plate glass 1b of FIG.
Of the S-polarized light Ls, and reflects the blue light B and the green light G, that is, the cyan light (C), and the red light R
To transmit light. The other surface 1bc of the sheet glass 1b
Then, the white light Lsw of the S-polarized light Ls is transmitted, and the blue light B and the green light G of the P-polarized light Lp, that is, the cyan light (C)
And red light R is reflected. By doing so, the P-polarized light Lp is converted into cyan light (C) as a whole.
, The red light R is reflected, the S-polarized light Ls reflects the cyan light (C), and a polarizing prism having characteristics of transmitting the red light R is obtained. Similarly, a polarizing prism in which the spectral characteristics of the polarizing prism and the P-polarized light and the S-polarized light are reversed can be obtained.

FIG. 6 shows the overall transmission spectral characteristics of one embodiment of the polarizing prism according to the present invention. Again, T represents the light transmittance. Similarly to the above, for example, on one surface 1ab of the plate glass 1b in FIG.
pw, transmit blue light B of S-polarized light Ls, and transmit red light R. The other side 1b of the sheet glass 1b
In c, the white light Lsw of the S-polarized light Ls is transmitted, the blue light B of the P-polarized light Lp is transmitted, and the red light R is reflected. By doing so, the P-polarized light Lp transmits the blue light B, reflects the red light R, and the S-polarized light Ls reflects the blue light B and transmits the red light R. A prism is obtained. In this case, the characteristics of the green light portion are arbitrary and the polarizing prism can be easily manufactured. Similarly,
A polarizing prism in which the spectral characteristics of the P-polarized light and the S-polarized light of the polarizing prism are reversed can also be obtained.

FIG. 7 shows the overall transmission spectral characteristics of one embodiment of the polarizing prism according to the present invention. Again, T represents the light transmittance. Similarly to the above, for example, on one surface 1ab of the plate glass 1b in FIG.
pw, transmit blue light B and red light R of S-polarized light Ls, that is, transmit magenta light (M) and reflect green light (G). Also, the other surface 1bc of the sheet glass 1b
In this case, white light (W) of S-polarized light Ls is transmitted, green light (G) of P-polarized light is transmitted, and blue light B and red light R, that is, magenta light (M) are reflected. By doing so, the P-polarized light Lp transmits the green light G and the blue light B and the red light R, that is, the magenta color light (M).
, The S-polarized light Ls reflects the green light G, and the blue light B
And a polarizing prism having a characteristic of transmitting the red light R, that is, the magenta light (M). Similarly, a polarizing prism in which the spectral characteristics of the P-polarized light and the S-polarized light of the polarizing prism are reversed can be obtained.

FIG. 8 is a conceptual diagram of an optical system of one embodiment of the reflection type light modulation projector according to the present invention. Lamp 81
The substantially parallel light beam L0 from the light source 81 including the light source a and the reflecting mirror 81b is converted into the P-polarized light Lp by the polarizer 82. The P-polarized light Lp is converted into green light Lpg and blue and red light, that is, magenta light Lpm, by a dichroic mirror 83 that reflects green light and transmits blue and red light. Green ray Lp
g is reflected by the PBS 84, which reflects the P-polarized green light of the P-polarized light and transmits the S-polarized light, and enters the polarization modulation element 85g, which receives the green light, modulates and reflects the green light. The green light reflected by the polarization modulation from the polarization modulation element 85g is subjected to PB
The light is re-entered at S84 and analyzed, only S-polarized light is transmitted, reflected by the dichroic mirror 87 that reflects green light, and is incident on the projection lens 88. On the other hand, dichroic mirror 8
The magenta light Lpm that has passed through 3 enters a polarizing prism 86 that reflects P-polarized light of blue light, transmits S-polarized light, transmits P-polarized light of red light, and reflects S-polarized light. The P-polarized light of the blue light reflected by the polarizing prism 86 is incident on a blue polarization modulation element 85b, and is polarized and modulated to be reflected.
Re-enter the polarizing prism 86. The re-entered blue light is analyzed by a polarizing prism 86 that transmits only S-polarized light, combined with the green light by a dichroic mirror 87 that transmits blue light and red light, and is incident on a projection lens 88. Similarly, the red P-polarized light transmitted through the polarizing prism 86 is
The light is incident on the polarization modulation element 85r for red, is polarization-modulated, is reflected, and is incident again on the polarization prism 86. The light is reflected and analyzed by a polarizing prism 86 that reflects only the S-polarized light of red light, and is combined with another color light by a dichroic mirror 87. By projecting the blue, red, and green light rays synthesized by the dichroic mirror 87 onto a screen with a projection lens that enters the light, and displaying a color image, a reflection-type light modulation projector can be obtained. With such an optical system configuration, a polarizing prism that can be easily manufactured can be used.

FIG. 9 is a conceptual diagram of an optical system of another embodiment of the reflection type light modulation projector according to the present invention. As above. Light source 8 including lamp 81a and reflecting mirror 81b
The substantially parallel light beam L0 from 1 is separated by the first polarizing prism 93 that reflects the S-polarized green light Lsg and transmits the P-polarized magenta light Lpm. The separated S-polarized green light Lsg reflects P-polarized light and transmits S-polarized light.
4 and is incident on a polarization modulation element 85g that receives and modulates and reflects the green light. The green light that has been polarization-modulated and reflected from the polarization modulation element 85g is incident again on the PBS 94, reflects and analyzes only the P-polarized light, and is reflected by the green light reflecting dichroic mirror 87. On the other hand, the polarizing prism 9
The magenta light Lpm that has passed through 3 enters a second polarizing prism 86 that reflects P-polarized light of blue light, transmits S-polarized light, transmits P-polarized light of red light, and reflects S-polarized light. The blue P-polarized light reflected by the polarizing prism 86 is incident on the blue polarization modulation element 85b, is polarization-modulated and reflected, and is incident again on the polarization prism 86. The re-entered blue light is analyzed by a polarizing prism 86 that transmits only S-polarized light, combined with the green light by a dichroic mirror 87 that transmits blue light and red light, and is incident on a projection lens 88. Similarly, the P-polarized light of red light transmitted through the polarizing prism 86 is incident on the polarization modulator 85r for red, is polarization-modulated, is reflected, and is incident on the polarization prism 86 again. The light is reflected and analyzed by a polarizing prism 86 that reflects only the S-polarized light of red light, and is combined with another color light by a dichroic mirror 87. By projecting the blue, red, and green light rays synthesized by the dichroic mirror 87 onto a screen with a projection lens that enters the light, and displaying a color image, a reflection-type light modulation projector can be obtained. Even with such an optical system configuration, a polarizing prism that can be easily manufactured as described above can be used.

[0029]

As described above, in a polarizing prism having a polarizing beam splitter function having a spectral characteristic by forming an optical thin film on a bonding surface of two triangular prism transparent media, the optical surface between both surfaces is formed on the bonding surface. A plate-shaped transparent medium having a parallel plane having a thickness sufficient to avoid interference is interposed, and one polarized light is transmitted between one surface of the plate-shaped transparent medium and the one triangular prism transparent medium, and Forming an optical thin film that reflects the other orthogonal polarized light with spectral characteristics and transmits the other polarized light between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium. A polarizing beam splitter function that forms an optical thin film that reflects the one polarized light with spectral characteristics and has spectral characteristics independent from each other for the one polarized light and the other polarized light orthogonal to the polarized light. Be prepared Polarizing prism can be obtained, by configuring the reflective optical modulation projector using this, it provides a reflective optical modulation projector can be downsized by shortening the optical path length of the optical system.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an embodiment of a polarizing prism according to the present invention.

FIG. 2 is a schematic plan view of another embodiment of the polarizing prism according to the present invention.

FIG. 3 is a conceptual plan view of still another embodiment of the polarizing prism according to the present invention.

FIG. 4A shows an embodiment of a polarizing prism according to the present invention.
These are transmission spectral characteristics on one surface of the plate medium, (B) transmission spectral characteristics on the other surface of the plate medium, and (C) transmission spectral characteristics of the polarizing prism as a whole.

FIG. 5A shows an embodiment of a polarizing prism according to the present invention.
These are transmission spectral characteristics on one surface of the plate medium, (B) transmission spectral characteristics on the other surface of the plate medium, and (C) transmission spectral characteristics of the polarizing prism as a whole.

FIG. 6 is an overall transmission spectral characteristic of one embodiment of the polarizing prism according to the present invention.

FIG. 7 is an overall transmission spectral characteristic of one embodiment of the polarizing prism according to the present invention.

FIG. 8 is a conceptual diagram of an optical system of one embodiment of a reflection type light modulation projector according to the present invention.

FIG. 9 is a conceptual diagram of an optical system of another embodiment of the reflection type light modulation projector according to the present invention.

FIG. 10 is a conceptual diagram of an optical system of an example of a conventional reflection type light modulation projector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Polarizing prism 1a, 1c Triangular prism 1b Thin glass 2 Square prism 2b Liquid 3 Square prism 3b Thin glass Lp P polarized light Ls S polarized light B Blue light G Green light R Red light T Transmittance 81 Light source 82 Polarizer 83 Dichroic mirror 84 PBS (Polarizing beam splitter) 85r, 85g, 85b Polarization modulating element 86 Polarizing prism 87 Dichroic mirror 88 Projection lens 93 Polarizing prism 94 PBS 101, 102, 104, 105 Dichroic mirror 103r, 103g, 103b PBS 108 Projection lens

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 9/31 H04N 9/31 C

Claims (16)

[Claims] In a polarizing prism having a polarizing beam splitter function in which an optical thin film is formed on a bonding surface of two triangular prism transparent media and having spectral characteristics, it is possible to avoid optical interference between both surfaces on the bonding surface. A plate-shaped transparent medium having a parallel plane with a sufficient thickness is interposed, and one polarized light beam is transmitted between one surface of the plate-shaped transparent medium and the one triangular prism transparent medium, and the other polarized light is orthogonal to this. Forming an optical thin film that reflects or transmits light with spectral characteristics, transmits the other polarized light between the other surface of the same plate-shaped transparent medium and the other triangular prism transparent medium, and transmits the other polarized light. Forming an optical thin film that reflects or transmits polarized light with spectral characteristics, and has a polarizing beam splitter function having spectral characteristics independent of each other for the one polarized light and the other orthogonal polarized light. Preparation A polarizing prism. 2. The polarizing prism according to claim 1, wherein the triangular prism transparent medium and the plate-shaped medium are made of optical glass of substantially the same quality. 3. The triangular prism medium is made of optical glass obtained by hollowing out the plate-shaped medium portion, and the optical thin film is formed on both surfaces of the optical glass in the hollowed-out portion.
2. The polarizing prism according to claim 1, wherein the liquid is a liquid having substantially the same refractive index as the optical glass filled in the hollow portion. 4. The two triangular prism media are divided by connecting a diagonal in a hollow portion of the quadrangular prism with a quadrangular prism formed of a hollow transparent medium and the plate-shaped medium having the optical thin film formed on both surfaces thereof. 2. The polarizing prism according to claim 1, wherein the hollow prisms are two hollow triangular prisms, and each hollow portion of the two hollow triangular prisms is filled with a liquid having substantially the same refractive index as the plate-shaped medium. 5. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light, transmits S-polarized light of a predetermined wavelength or more, and S-polarized light of a predetermined wavelength or less. With the property of reflecting light, the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium transmits S-polarized light, transmits P-polarized light of a predetermined wavelength or less, and transmits light of a predetermined wavelength or more. 2. The device according to claim 1, wherein the device has a property of reflecting P-polarized light.
The polarizing prism as described. 6. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits S-polarized light, transmits P-polarized light of a predetermined wavelength or more, and P-polarized light of a predetermined wavelength or less. With the property of reflecting light, the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium transmits P-polarized light and transmits S-polarized light having a predetermined wavelength or less and transmits a predetermined wavelength or more. S
2. The polarizing prism according to claim 1, wherein the polarizing prism has a characteristic of reflecting polarized light. 7. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light white light (W) and S-polarized light green and red light (Y ) And reflects the blue light (B), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium is S
Transmits white light (W) of polarized light and blue light (B) of P-polarized light
The polarizing prism according to claim 5, wherein the polarizing prism has a characteristic of transmitting green light and reflecting green and blue light (Y). 8. An optical thin film between one surface of said plate-shaped transparent medium and one triangular prism transparent medium transmits S-polarized light white light (W) and P-polarized light green and red light (Y ) And reflects the blue light (B), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium is P
S-polarized blue light (B) that transmits polarized white light (W)
7. The polarizing prism according to claim 6, wherein the polarizing prism has a characteristic of transmitting green light and reflecting green and blue light (Y). 9. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light white light (W) and S-polarized light red light (R). It has the property of transmitting and reflecting blue and green light (C), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium is S
The polarizing prism according to claim 5, wherein the polarizing prism has a characteristic of transmitting white light (W) of polarized light, transmitting blue and green light (C) of P-polarized light, and reflecting red light (R). 10. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits white light (W) of S-polarized light and transmits red light (R) of P-polarized light. With the property of transmitting and reflecting blue and green light (C), the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium has P
7. The polarizing prism according to claim 6, wherein the polarizing prism has a characteristic of transmitting white light (W) of polarized light, transmitting blue and green light (C) of S-polarized light, and reflecting red light (R). 11. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light white light (W) and transmits S-polarized light red light (R). It has the property of transmitting and reflecting blue light (B), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium transmits S-polarized light white light (W) and P-polarized light. The polarizing prism according to claim 5, wherein the polarizing prism has a characteristic of transmitting blue light (B) and reflecting red light (R). 12. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits white light (W) of S-polarized light and transmits red light (R) of P-polarized light. It has the property of transmitting and reflecting blue light (B), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium transmits P-polarized light white light (W) and S-polarized light. The polarizing prism according to claim 6, wherein the polarizing prism has a characteristic of transmitting blue light (B) and reflecting red light (R). 13. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits P-polarized light white light (W) and S-polarized light blue light and red light (W). M) and has a characteristic of reflecting green light (G), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium transmits white light (W) of S-polarized light. 2. The polarizing prism according to claim 1, wherein the polarizing prism has a characteristic of transmitting green light (G) of P-polarized light and reflecting blue light and red light (M). 14. An optical thin film between one surface of the plate-shaped transparent medium and one triangular prism transparent medium transmits S-polarized light white light (W) and P-polarized light blue light and red light (W). M) and transmits green light (G), and the optical thin film between the other surface of the plate-shaped transparent medium and the other triangular prism transparent medium transmits white light (W) of P-polarized light. 2. The polarizing prism according to claim 1, wherein the polarizing prism has a characteristic of transmitting green light (G) of S-polarized light and reflecting blue light and red light (M). 15. A reflection type light modulation projector for displaying a color image by modulating a light beam from a light source by a combination of a plurality of reflection type polarization modulation elements and a polarization prism and projecting the light beam on a screen by a projection lens. A polarizer that converts the light from the light source into P-polarized light, a dichroic mirror that reflects green light of the same P-polarized light and transmits blue and red light, and reflects P-polarized light of the reflected green light and converts S-polarized light into A polarizing beam splitter (hereinafter referred to as a PBS) that transmits, a P-polarized green light reflected by the PBS, polarization-modulated and reflected and reflected again by the PBS, and transmitted through the dichroic mirror. A polarizing prism that reflects P-polarized light of blue light, transmits S-polarized light, transmits P-polarized light of red light, and reflects S-polarized light; Receiving P-polarized light of blue light reflected by the polarizing prism, polarization-modulating the reflected light, reflecting it, and re-entering the same polarizing prism, and receiving P-polarized light of red light transmitted through the same polarizing prism. A polarization modulator for red, which is polarized and reflected and re-enters the same polarizing prism, and an S-polarized red light which is analyzed by transmitting S-polarized light of blue light re-entered by the same polarizing prism. The light is reflected and analyzed, and the green light re-entering the PBS is reflected by the PB.
A dichroic mirror that detects and emits light at S, transmits blue and red light emitted from the prism, and reflects green light emitted from the PBS, and receives blue, red, and green light emitted from the dichroic mirror. A reflection-type light modulation projector comprising a projection lens for projecting light. 16. A reflection-type light modulation projector that modulates a light beam from a light source by a combination of a plurality of reflection-type polarization modulation elements and a polarization prism and projects the color image on a screen by a projection lens to display a color image. A first polarizing prism that transmits blue light and red light of P-polarized light and reflects green light of S-polarized light among the light from the light source, and transmits S-polarized light of green light reflected by the same polarizing prism. PBS that reflects P-polarized light, S-polarized light that passes through the PBS, receives polarization-modulated light, reflects the polarization, and re-enters the PBS. A green polarization modulation element, and P that transmits through the first polarizing prism.
Among the polarized light, a second polarizing prism that reflects blue light, transmits S-polarized light of blue light, transmits red light, and reflects P-polarized light of red light, and P-polarized light of blue light reflected by the same polarizing prism The polarization modulator for blue, which receives and modulates the polarized light, reflects the reflected light, and re-enters the same polarizing prism, and receives the P-polarized light of the red light transmitted through the same polarizing prism, modulates the polarized light, reflects the reflected light, and re-enters the same polarizing prism. The incident polarization modulator for red and the blue light re-entered into the same polarizing prism are analyzed, the S-polarized light is transmitted, the red light is analyzed, and the S-polarized light is reflected and emitted,
The dichroic mirror reflects the green light re-entering the PBS, detects and emits P-polarized light, transmits the emitted blue and red light, and reflects the green light, and blue and red emitted from the dichroic mirror. And a projection lens for projecting and projecting a green light ray.