JPH0980356A - Projection device equipped with polarization beam splitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection device which is affected a little by a prism used for the polarization beam splitter. SOLUTION: This device is equipped with a light source 8, a spatial optical modulating element 4, a projection optical system 6, and the polarization beam splitter 3 which polarizes the light source light emitted by the light source 8 and guides it to the spatial optical modulating element 4, and also guides the light modulated optically by the spatial optical modulating element 4 to the projection optical system 6. The polarization beam splitter 3 has a polarizing film which reflects a 1st polarized component and transmits a 2nd polarized component different from the 1st polarized component and two prism groups which are connected together across the polarizing film, and one prism group is constituted by alternately forming a 1st surface which is at 45 deg. to the polarizing film and a 2nd surface which crosses the 1st surface at right angles and the other prism group is constituted by alternately forming a 3rd surface which is parallel to the 1st surface and a 4th surface which crosses the 3rd surface at right angles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection device including at least a polarization beam splitter that reflects a predetermined first polarization component and transmits a second polarization component different from the first polarization component.

[0002]

2. Description of the Related Art A polarization beam splitter is known as one of optical elements for separating a light source emitted from a light source into two polarization components. This polarizing beam splitter
For example, it is configured as shown in FIG. The conventional example shown in FIG. 12 includes a polarizing film 71 and two prisms 72 and 73 integrated with the polarizing film 71 interposed therebetween. When the light source light as shown in FIG. 12 enters the polarization beam splitter 70, the polarization film 71 transmits the P polarization component,
Reflect the S-polarized component.

The polarization beam splitter having such characteristics is also used in a projection device for enlarging and projecting an image on a screen. FIG. 13 shows an example of the projection device. This projection device includes a screen 74, an illumination system 75 for irradiating light from a light source, a polarization beam splitter 70 of the type shown in FIG. 12, a writing optical system 76 for generating writing light, and a polarization beam splitter 70. The light of
It includes a spatial light modulator 77 that generates an image by performing light modulation according to the writing light, and a projection optical system 78 that magnifies and projects the light from the polarization beam splitter 70 onto the screen 74.

Light from the light source emitted from the illumination system 75 enters the polarization beam splitter 70, and in the polarization film 71,
It is separated into an S-polarized component and a P-polarized component. The S-polarized component reflected by the polarizing film 71 is read out and incident on the spatial light modulator 77 as light. The spatial light modulator 77 optically modulates the read light by the write light having the image information, which is emitted from the write optical system 76, and reflects the read light. A part of the reflected read-out light becomes a P-polarized component due to the phase shift caused by the light modulation, and in this state, it again enters the polarization beam splitter 70. Then, of the light that has entered the polarization beam splitter 70, the P-polarized component that is a modulated component is transmitted through the polarizing film 71, and the S-polarized component that is an unmodulated component is reflected by the polarizing film 71. The P-polarized component that has passed through the polarizing film 71 is enlarged by the projection optical system 78 and projected on the screen 74.

By the way, optical glass is usually used for the prisms 72 and 73 of the polarization beam splitter 70. Usually, the glass material has a birefringent property because it is formed in a state in which strain due to internal stress or the like is included. of course,
The optical glasses mentioned above are no exception. Then, the optical glass having the birefringence has a bad influence on the light transmitted therethrough. For example, in FIG. 13, the prism 73 of the polarization beam splitter 70 disturbs the P-polarized component that has passed through the polarizing film 71 and changes a part of it to the S-polarized component. In such a case, light other than the light modulated by the spatial light modulator 77 will enter the projection optical system 78. If light other than the modulated light is incident, the projection optical system 78 cannot project an accurate image, and as a result, uneven illuminance or uneven color appears on the screen.

In order to solve the above problems, for example,
Conventionally, a method of annealing a glass material used as a prism to reduce distortion, and a method of using a glass material having a small photoelastic coefficient have been used.

[0007]

However, as long as the glass material is used, in any of the above methods,
The light will be affected as much as it passes there.

Therefore, as a method not using a glass material,
For example, a polarization beam splitter of the type shown in FIG. 14 has been proposed. This polarization beam splitter 80
Is composed of a cubic case 82 and a substrate 81 on which a polarizing film (not shown) is formed. Case 82
The inside is filled with liquid. The substrate 81 is submerged in this liquid. In this way, if the liquid is used instead of the glass material, there is no influence due to the distortion of the glass material as described above.

However, in the polarization beam splitter shown in FIG. 14, an incident surface 82a through which incident light on the polarizing film passes and an exit surface 82b through which reflected light from the polarizing film passes.
In order to set the angle formed by and to 90 °, the refractive index of the liquid filled inside is 1.7 to 1.9 because of the design of the polarizing film.
Need to be on the order. However, such high refractive index liquids generally have unstable properties.

Therefore, when incorporating a liquid-filled type polarization beam splitter into a product, there is no choice but to use a liquid having a low refractive index of about 1.5 to 1.6. If the refractive index of the liquid becomes low, of course, the optical performance is inevitably reduced.

In order to maintain the optical performance, there is a method of forming the case as shown in FIG. 15 and increasing the angle α formed by the incident light and the reflected light. The reason why the angle α has to be increased arises from a problem in thin film design. In any case, however, the configuration as shown in FIG. 15 not only makes the polarization beam splitter large but also increases the size of the optical system. Becomes complicated.

In addition, the polarization beam splitters of the type filled with liquid, including those shown in FIG. 14, generally require complicated liquid injection work and are difficult to maintain. Therefore, the polarization beam splitter using the glass material as described above is much easier to handle.

In consideration of such a problem, an object of the present invention is to provide a projection device in which the influence of the prism of the polarization beam splitter is small.

[0014]

According to a first aspect of the present invention for achieving the above object, a light source, a spatial light modulator, a projection optical system, and a source light emitted from the light source are polarized. And a polarization beam splitter that guides the light optically modulated by the spatial light modulation element to a projection optical system while guiding the light to the spatial light modulation element. Reflects the polarized component of
A polarizing film that transmits a second polarized light component different from the first polarized light component and two prism groups that are bonded to each other via the polarizing film are provided, and one prism group of the two prism groups is , A first surface forming an angle of 45 ° with the polarizing film and a second surface orthogonal to the first surface are alternately formed, and the other prism of the two prism groups is formed. The group comprises a third surface parallel to the first surface,
A projection device provided with a polarization beam splitter, characterized in that a fourth surface orthogonal to the third surface is formed alternately.

According to a second aspect of the present invention for achieving the above object, in the first aspect, the arrangement is provided between the polarization beam splitter (referred to as a first polarization beam splitter) and the projection optical system. And a polarizing film that reflects the first polarized light component and transmits the second polarized light component, It is provided with two prism groups joined via a polarizing film,
In one prism group of the two prism groups, a first surface forming an angle of 45 ° with the polarizing film and a second surface orthogonal to the first surface are alternately formed. In the other prism group of the two prism groups, a third surface parallel to the first surface and a fourth surface orthogonal to the third surface are alternately formed. Provided is a projection device having a polarization beam splitter.

According to a third aspect of the present invention for achieving the above-mentioned object, in the first or second aspect, a polarization beam splitter disposed between the light source and the first polarization beam splitter ( A third polarization beam splitter), wherein the third polarization beam splitter is
One prism of the two prism groups includes a polarizing film that transmits the first polarized component and reflects the second polarized component, and two prism groups that are bonded to each other via the polarizing film. The group is formed by alternately forming a first surface forming an angle of 45 ° with respect to the polarizing film and a second surface orthogonal to the first surface, and the other of the two prism groups. Is a polarizing beam splitter, wherein a third surface parallel to the first surface and a fourth surface orthogonal to the third surface are alternately formed. Provided is a projection device.

According to a fourth aspect of the present invention for achieving the above object, in the first, second or third aspect,
The first surface, the second surface, the third surface, and
There is provided a projection device including a polarization beam splitter, wherein each of the fourth surfaces has the same area.

According to a fifth aspect of the present invention for achieving the above object, in the first, second, third or fourth aspect, the one prism group includes the first surface and the first surface. There is provided a projection device including a polarization beam splitter, which is one prism in which second surfaces are alternately and continuously formed.

According to a sixth aspect of the present invention for achieving the above object, in the first, second, third, fourth or fifth aspect, the other prism group is the third prism group. There is provided a projection device including a polarization beam splitter, which is one prism in which a surface and the fourth surface are alternately and continuously formed.

According to a seventh aspect of the present invention for achieving the above object, in the first, second, third, fourth, fifth or sixth aspect, the first surface, the There is provided a projection device including a polarization beam splitter, wherein an absorption film is formed on any one of the second surface, the third surface, and the fourth surface. It

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a projection apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. The projection device 1 includes an illumination system 2, a polarization beam splitter 3, a spatial light modulator 4, and a writing optical system 5.
And a projection optical system 6. A screen 7 is arranged in front of the projection optical system 6.

In the illumination system 2, a light source 8, a reflecting mirror 9 for reflecting the light source light emitted from the light source 8, and a light source light reflected by the reflecting mirror 9 are collimated and guided to a polarization beam splitter 3. A lens 10 is provided. The light source 8 includes a xenon lamp, a metal halide lamp, a halogen lamp,
A lamp or the like is used.

The spatial light modulator 4 is for performing intensity modulation or phase modulation with incident light as a two-dimensional spatial plane based on given image information, and has an address function for designating a position within the plane and an optical modulation. It has both functions. In this embodiment, a liquid crystal display panel is used as the spatial light modulator 4. Liquid crystal display panels are generally classified into a transmissive type and a reflective type. Here, a reflective type is used because of the form of the optical system. This reflective liquid crystal display panel is provided with a photoconductive layer or a liquid crystal layer between a pair of transparent electrodes, and when writing light containing image information is projected on the photoconductive layer, light is emitted depending on the brightness. The electric resistance of the conductive layer changes for each in-plane region, and as a result, the liquid crystal layer is configured to exhibit an electro-optical modulation effect according to image information.

The writing optical system 5 emits the above-mentioned writing light. A CRT or a transmissive liquid crystal display panel can be used as the writing optical system 5.
In addition, for example, XY
If the image information is directly and electrically written by using the one having the matrix electrode structure, the writing optical system 5 becomes unnecessary.

The projection optical system 6 is provided with a projection lens (not shown) for enlarging and projecting the image on the spatial light modulator 4 obtained through the polarization beam splitter 3 onto the screen 7.

Here, the structure of the polarization beam splitter 3 will be described.

As shown in FIG. 2, the polarization beam splitter 3 includes six small optical elements (small optical elements 11a to 11).
f) and support members 40 and 41 for fixing them. The number of small optical elements is not limited to this embodiment, and may be increased or decreased as necessary. As shown in FIG. 3, each small optical element has a prism 20 having a predetermined length and a cross section of an isosceles right triangle, and a prism 20 slightly longer than the prism 20 and having the same cross section as the prism 20. And the prism 30.
In this embodiment, optical glass is used for each of the prism 20 and the prism 30. Of course, a plastic material may be used. On the slope of the prism 20,
As shown in FIG. 4, the polarizing film 50 is vapor-deposited. For the polarizing film 50, for example, a dielectric thin film that absorbs little light is used. The inclined surface of the prism 30 is bonded to the polarizing film 50 with an adhesive material 51. The adhesive material 51 is an optical adhesive material in consideration of the optical characteristics (refractive index, etc.) of each prism. Therefore, the adhesive material 51 does not affect the light passing therethrough.

An AR coat (antireflection film) may be vapor-deposited between the adhesive 51 and the slope of the prism 30. By doing so, it is possible to prevent the light transmitted through the polarizing film 50 from being reflected on the inclined surface of the prism 30.

In manufacturing the polarization beam splitter 3, for example, the prism 20 is first bonded to the prism 30 so that fixing margins are secured at both ends of the prism 30. After the required number of integrated prisms 20 and 30 (small optical elements) are prepared, they are fixed to the support members 40 and 41 in a state where they are adjacent to each other, as shown in FIG. At this time, the polarizing film 50 of each small optical element comes to be located on the same plane. An optical adhesive may be used for joining the fixing margins at both ends of the prism 30 and the supporting members 40 and 41.

Next, the operation of the projection apparatus 1 will be described with reference to FIG.
This will be described with reference to FIG. In addition, in the polarization beam splitter 3, in order to simplify the description, the description is advanced by focusing on the small optical elements 11c and 11d.

The light source light emitted from the light source 8 is reflected by the reflecting mirror 9.
And is supplied to the collimating lens 10. The supplied light source light is made into a parallel light flux by the collimating lens 10 and enters the polarization beam splitter 3. The incident light source light is separated into two polarization components by the polarization film 50. Specifically, as shown in FIG. 5, the light source light is emitted from the first surface 21 of the prism 20.
Then, one polarization component (S polarization component) is reflected by the polarization film 50, and the other polarization component (P polarization component) is transmitted through the polarization film 50. The reflected S-polarized component is emitted from the second surface 22 of the prism 20. The transmitted P-polarized component is emitted from the third surface 31 of the prism 30. still,
In the polarizing film 50, the S-polarized component is reflected at right angles to the light source light.

Further, in FIG. 5, the outline of the conventional polarization beam splitter is shown by a dotted line. A scale corresponding to the size of the prism 20 (prism 30) is provided in the middle of the dotted line.

According to this embodiment, the optical path length (l) in the prism 20 required by the light source light and the S-polarized component
Is the optical path length (L) in the conventional polarization beam splitter
1 / n (n: the number of small optical elements, which is “6” in this embodiment). The optical path length required by the light source light and the P-polarized component is also 1 / n as compared with the conventional one. The same applies to other small elements.

Usually, in order to set the angle between the light incident on the polarizing film (for example, the above-mentioned light source light) and the reflected light from the polarizing film (for example, the above S-polarized component) to 90 °, the polarizing film is required. In terms of the design, it is necessary to use optical glass having a high refractive index for the two prisms that sandwich the polarizing film. However, an optical glass having a high refractive index generally absorbs a short wavelength light and has a low transmittance. Therefore, the amount of transmitted light of short wavelength light (blue light) decreases as the optical path length increases.

Therefore, in the present embodiment, the polarization beam splitter 3 is used to shorten the optical path length in the prism to reduce the absorption of light in the prism and the influence of distortion of the prism.

According to the polarization beam splitter 3 of the present embodiment, the capacity of the glass material used for the prism is reduced as compared with the conventional one, so that the cost can be reduced. Of course, the space occupied by the polarization beam splitter is also reduced as the volume of the glass material is reduced.

Now, the S-polarized light component emitted from the second surface 22 of the prism 20 is applied to the spatial light modulator 4. In the spatial light modulation element 4, a part of this S-polarized component is converted into a P-polarized component according to the writing light from the writing optical system 5, and then enters the second surface 22 of the prism 20. Specifically, in the liquid crystal layer inside the liquid crystal display used as the spatial light modulator 4, the incident S-polarized component is rotated and becomes a P-polarized component.
Since the function of the liquid crystal layer as the optical rotatory substance is well known, the description thereof is omitted here.

In the polarizing film 50, of the incident light, the S-polarized component is reflected and the P-polarized component is transmitted. The transmitted P-polarized component is emitted from the fourth surface 32 of the prism 30. The P-polarized light component emitted from the prism 30 passes through the projection optical system 6 and then is irradiated on the screen 7. In the screen 7, the area irradiated with the P-polarized component becomes the bright portion, and the area reflected by the S-polarized component becomes the dark portion. The image on the liquid crystal display is reproduced by these light and dark. The image on the screen 7 is enlarged and projected by the projection optical system 6.

Further, the optical path length from the second surface 22 of the prism 20 to the fourth surface 32 of the prism 30 is 1 / n of that of the conventional polarization beam splitter as described above. Therefore, also in this case, the influence of the distortion of the prism and the absorption of light in the prism are reduced. That is, the image of the screen 7 becomes clearer as the influence of the distortion of the prism is less and becomes brighter as the influence of the absorption of light in the prism is less.

The above is the configuration and operation of the projection apparatus 1, but the polarization beam splitter used may be configured as shown in FIG. 6, for example.

The polarization beam splitter 103 includes a plurality of prisms 30 instead of the third surface 31.
The substrate 60 in which the fourth surfaces 32 are alternately formed in a staircase is used. For the substrate 60, for example, a glass material is used. Like the polarization beam splitter 3, the third surface 31 and the fourth surface 32 are orthogonal to each other. The polarizing film is vapor-deposited on the inclined surface of the substrate 60, although not particularly shown. A plurality of prisms 20 are fixed on the polarizing film. The first surface 21 of the prism 20 is parallel to the third surface 31 of the substrate 60, and the prism 20
The second surface 22 of the is parallel to the fourth surface 32 of the substrate 60. Of course, it is also possible to provide the above-described antireflection film on the polarization beam splitter. According to this polarization beam splitter, since the substrate 60 itself serves as a supporting member, the member strength can be increased.

The polarization beam splitter incorporated in the projection apparatus 1 may be constructed as shown in FIG.

The polarization beam splitter 203 includes the above-mentioned substrate 60 and a substrate 61 in which the first surface 21 and the second surface 22 are alternately formed in a step shape. These substrates are joined by an optical adhesive material. According to the present polarization beam splitter, the member strength can be increased and the number of parts can be reduced as compared with the polarization beam splitter of FIG.

The polarization beam splitter incorporated in the projection device 1 may be further configured as shown in FIG.

The polarization beam splitter 303 has an absorption film 53 formed on the third surface 31 of the prism 30 (see FIG. 5). The absorption film 53 has a characteristic of absorbing the light transmitted through the polarizing film 50. Therefore, the phenomenon that the light transmitted through the polarizing film 50 is reflected by the third surface 31 of the prism 30 and interferes with the light passing through the fourth surface 32 does not occur.

Now, usually, the polarization beam splitter has a predetermined extinction ratio. The extinction ratio represents the ratio of the P-polarized component and the S-polarized component contained in the transmitted light (or the reflected light), but the incident light is completely separated into the P-polarized component and the S-polarized component. Although it is theoretically possible to envision such a polarization beam splitter, it is practically impossible to manufacture it as an optical element.

The polarization beam splitter 3 of this embodiment is not an exception, and it is conceivable that light other than the P-polarized component (for example, S-polarized component) is emitted toward the projection optical system 6. Further, in detail, since the complete P polarization component and S polarization component cannot be obtained from the spatial light modulation element 4, the polarization beam splitter 3
It is conceivable that unwanted light may be mixed with the emitted light of the.

In consideration of the above, in the projection apparatus 101 (see FIG. 9) of the second embodiment of the present invention, the polarization beam splitter 3 is further provided between the polarization beam splitter 3 and the projection optical system 6. A polarization beam splitter 3'having the same configuration as that of is arranged. The other components are the same as those in the first embodiment, and therefore the same reference numerals are given and the description thereof is omitted.

According to the present embodiment, even if the S-polarized component is mixed in the light emitted from the polarization beam splitter 3, it can be reflected by the polarization beam splitter 3 '. Of course, a plurality of polarization beam splitters 3 ′ may be arranged between the polarization beam splitter 3 and the projection optical system 6 to further improve the filtering function.

FIG. 10 shows a third embodiment of the present invention.

This projection device 102 is provided with a polarization beam splitter 3 "having the same structure as that of the polarization beam splitter 3 between the illumination system 2 and the polarization beam splitter 3. The polarization beam splitter 3" includes the polarization beam splitter 3 ". The polarizing film is arranged in a state of being rotated by 90 ° with respect to the polarizing film of the polarization beam splitter 3.

Therefore, in the polarization beam splitter 3 ″, of the light source light from the illumination system 2, the light corresponding to the above-mentioned P-polarized component is reflected and the light corresponding to the above-mentioned S-polarized component is transmitted. Specifically, when the polarization beam splitter 3 ″ is arranged so that the upper portion (3a portion) of the polarizing film is located on the back side of the paper surface, the light corresponding to the above P-polarized component is on the front side. When the polarization beam splitter 3 ″ is arranged so that it is reflected and the 3a part is located on the front side, the light corresponding to the P-polarized component is reflected on the back side.

As described above, if the P-polarized light component is reflected in the preceding stage of the polarization beam splitter 3, the S-polarized light component reflected by the polarization beam splitter 3 becomes better. Of course, a plurality of polarization beam splitters 3 ″ may be arranged in series.

FIG. 11 shows a fourth embodiment of the present invention.

This projection device 103 includes the polarization beam splitter 3'used in the second embodiment and the polarization beam splitter 3 "used in the third embodiment. Both effects can be obtained.

Although the first to fourth embodiments of the present invention have been described above, the present invention may be configured using, for example, a color liquid crystal display.

In this case, R (Red), G (Green), B
A liquid crystal panel may be prepared for each of the three primary colors of (Blue), and each panel may generate an image corresponding to each color. The polarization beam splitter according to the present invention is arranged so as to supply the incident light to each liquid crystal panel and to receive the combined light of the light of each color which has undergone the light modulation. Of course, the configuration of the color liquid crystal display is not limited to these configurations. The image projected on the screen may be either a still image or a moving surface.

In each of the second to fourth embodiments, the polarization beam splitter shown in FIG. 2 has been described as an example, but the polarization beam splitters shown in FIGS. 6 to 8 may be used in each embodiment. Absent.

[0060]

According to the present invention, it is possible to obtain projection light that is less influenced by the prism of the polarization beam splitter, and therefore it is possible to reproduce an image with little unevenness in illuminance or uneven color on the screen.

[0061]

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of a projection device according to the present invention.

FIG. 2 is a perspective view of a polarization beam splitter (No. 1) used in each embodiment of the projection apparatus according to the present invention.

FIG. 3 is a perspective view of a small optical element that constitutes the polarization beam splitter of FIG.

FIG. 4 is an explanatory view of a small optical element that constitutes the polarization beam splitter of FIG.

5 is an explanatory diagram related to an optical path of the polarization beam splitter in FIG.

FIG. 6 is an explanatory diagram of a polarization beam splitter (No. 2) according to each embodiment of the projection device of the present invention.

FIG. 7 is an explanatory diagram of a polarization beam splitter (No. 3) according to each embodiment of the projection device of the present invention.

FIG. 8 is an explanatory diagram of a polarization beam splitter (No. 4) according to each embodiment of the projection device of the present invention.

FIG. 9 is a block diagram of a second embodiment of a projection device according to the present invention.

FIG. 10 is a block diagram of a third embodiment of a projection device according to the present invention.

FIG. 11 is a block diagram of a fourth embodiment of a projection device according to the present invention.

FIG. 12 is an explanatory diagram of a conventional polarization beam splitter (1).

FIG. 13 is a block diagram showing a configuration example of a projection device using a conventional polarization beam splitter.

FIG. 14 is an explanatory diagram of a conventional polarization beam splitter (No. 2).

FIG. 15 is an explanatory diagram of a conventional polarization beam splitter (3).

[Explanation of symbols]

1, 101, 102, 103: Projection device, 2, 75:
Illumination system, 3, 3 ', 3 ", 70, 80, 103, 20
3, 303: Polarizing beam splitter, 4, 77: Spatial light modulator, 5, 76: Writing optical system, 6, 7
8: projection optical system, 7, 74: screen, 8: light source,
9: Reflecting mirror, 10: Parallelizing lens, 11a-11
f: small optical element, 20, 30: prism, 40,
41: support member, 50, 71: polarizing film, 51: adhesive material, 53, absorption film, 60, 61, 81: substrate, 7
2, 73: prism, 82: case

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshiro Oikawa 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon (72) Inventor Tetsuo Hattori 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Company Nikon

Claims (7)

[Claims] 1. A light source, a spatial light modulator, a projection optical system, and a light source light emitted from the light source, which is polarized and guided to the spatial light modulator, and which is optically modulated by the spatial light modulator. In a projection optical system, the polarization beam splitter reflects a predetermined first polarization component and outputs a second polarization component different from the first polarization component. A polarizing film that transmits light and two prism groups that are bonded to each other via the polarizing film are provided, and one prism group of the two prism groups has a first surface that forms an angle of 45 ° with respect to the polarizing film. And a second surface orthogonal to the first surface are alternately formed, and the other prism group of the two prism groups has a third surface parallel to the first surface. Surface and a fourth surface orthogonal to the third surface , Projection device having the polarizing beam splitter characterized by comprising alternately formed. 2. The polarization beam splitter according to claim 1, further comprising a polarization beam splitter (referred to as a second polarization beam splitter) arranged between the polarization beam splitter (referred to as a first polarization beam splitter) and the projection optical system. The second polarization beam splitter includes a polarization film that reflects the first polarization component and transmits the second polarization component, and two prism groups that are joined together via the polarization film, One prism group of the two prism groups is formed by alternately forming a first surface forming an angle of 45 ° with respect to the polarizing film and a second surface orthogonal to the first surface, In the other prism group of the two prism groups, a third surface parallel to the first surface and a fourth surface orthogonal to the third surface are alternately formed. Polarized beam split characterized by Projector equipped with a shutter. 3. The polarization beam splitter according to claim 1, further comprising a polarization beam splitter (referred to as a third polarization beam splitter) arranged between the light source and the first polarization beam splitter. Includes a polarizing film that transmits the first polarized light component and reflects the second polarized light component, and two prism groups joined together via the polarizing film, one of the two prism groups The prism group of is formed by alternately forming a first surface forming an angle of 45 ° with respect to the polarizing film and a second surface orthogonal to the first surface. The other prism group of <1> is formed by alternately forming a third surface parallel to the first surface and a fourth surface orthogonal to the third surface. Projector equipped with a beam splitter. 4. The method according to claim 1, 2 or 3, wherein:
Surface, the second surface, the third surface, and the fourth surface
Each of the surfaces has an area equal to each other. 5. The prism group according to claim 1, 2, 3 or 4, wherein the one prism group is a prism in which the first surface and the second surface are alternately and continuously formed. A projection device equipped with a polarizing beam splitter. 6. The prism according to claim 1, 2, 3, 4 or 5, wherein the other prism group is formed by alternately and continuously forming the third surface and the fourth surface. A projection device equipped with a polarizing beam splitter. 7. The method according to claim 1, 2, 3, 4, 5 or 6, wherein the first surface, the second surface, the third surface, and
A projection device having a polarization beam splitter, wherein an absorption film is formed on any one of the fourth surfaces.