JPH11149013A - Polarizing separating device polarization illuminator, projection type display device and manufacture of polarizing separating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin polarizing separating device splitting natural light into two polarization components having a different polarization direction and emitting two polarization components in mutually different directions. SOLUTION: A polarizing separating element 45 is constituted by sticking a member obtained by the vapour deposition of polarizing separating film 42 on the slant face of a first prism 41 and a second prism 43 by a transparent adhesive 46. Plural polarizing separating elements 45 are stuck and formed into a plate-like shape by the transparent adhesive 46. The refractive index of the second prism 43 is lower than that of the first prism 41. When the natural light is made incident on the first prism 41 along an optical axis, a P- polarization component is transmitted through the polarizing separating film 42 and is emitted in a direction deviated from the optical axis, and an S- polarization component is reflected by the polarizing separating film 42, and is reflected by the other polarizing separating film 42 adjacent and is emitted in a direction in parallel with the optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization separation device for separating natural light into two linearly polarized lights having different traveling directions, an illumination optical device using the polarization separation device, and a projection display device using the illumination optical device. And a method of manufacturing the polarization separation device.

[0002]

2. Description of the Related Art In order to obtain a large screen image, a method of forming an optical image according to an image signal on a light valve, irradiating the optical image with light, and enlarging and projecting the image on a screen by a projection lens has been conventionally used. well known. Recently, a projection type display device using a liquid crystal panel as a light valve has attracted attention (for example, Japanese Patent Application Laid-Open No. 62-133424). The LCD panel is used to obtain high quality projected images.
It is becoming mainstream to use twisted nematic (TN) liquid crystal as a liquid crystal material, use an active matrix type in which a TFT is provided for each pixel as a switching element, and use three liquid crystal panels for red, green, and blue. .
Recently, the uniformity of illuminance of a projected image has been improved by using an integrator in which two lens array plates are combined.

FIG. 15 shows a conventional example of a configuration of an optical system of a projection display device using a TN liquid crystal and an integrator. The light source 14 is composed of the lamp 11, the concave mirror 12, and the filter 13. The light emitted from the lamp 11 is converted into near parallel light by the concave mirror 12, and the filter 13 removes infrared light and ultraviolet light. Light emitted from the light source 14 is incident on an integrator 17 in which the incident side lens array 15 and the exit side lens array 16 are combined. The incident-side lens array 15 is a two-dimensional array of a plurality of positive lens elements 18 having the same rectangular aperture, and the emission-side lens array 16 includes a plurality of positive lens elements 19 corresponding to each positive lens element 18. They are arranged two-dimensionally. The light emitted from the integrator 17 is reflected by the dichroic mirror 2
The light enters a color separation optical system composed of 0, 21 and a plane mirror 22, and is separated into light of three primary colors of red, green, and blue. Each primary color light is transmitted to a field lens 23, 24, 25, respectively.
And, after passing through the incident side polarizing plates 26, 27, 28,
The light enters the liquid crystal panels 29, 30, and 31.

Each positive lens element 18 forms a real image corresponding to the illuminant of the lamp 11 on the corresponding positive lens element 19. Each positive lens element 19 outputs a real image corresponding to the aperture of the corresponding positive lens element 18 to each of the liquid crystal panels 26, 27,
28 and illuminate an area slightly larger than their display area. The liquid crystal panel 29 is formed by the fact that the brightness unevenness in the positive lens element 18 is smaller than the entire brightness unevenness on the incident side lens array 15 and that the output side lens array 16 forms a real image obtained by rotating the object by 180 °. , 3
Since the illuminance uniformity formed on 0 and 31 is improved, the illuminance distribution of the projected image is finally made uniform.

An optical image is formed on the liquid crystal panels 29, 30, 31 based on a change in transmittance according to a video signal.
Outgoing light from the liquid crystal panels 29, 30, 31 passes through the outgoing-side polarizers 32, 33, 34, respectively, and then becomes one light by a color combining optical system composed of dichroic mirrors 35, 36 and a plane mirror 37. Are incident on the projection lens 38, thereby the three liquid crystal panels 2
The optical images on 9, 30, 31 are enlarged and projected on a screen (not shown) by the projection lens 38.

[0006]

The TN liquid crystal panels 29, 3 used in the conventional projection display device shown in FIG.
0 and 31 require polarizing plates 26, 27 and 28 on the incident side. These incident-side polarizers 26, 27, and 28 are used to convert natural light emitted from the light source 14 into linearly polarized light. However, since they absorb about half of the incident light, the light utilization efficiency of the entire apparatus is low. There is.

In order to solve this problem, there has been proposed an optical system in which a polarization separation device for converting natural light into linearly polarized light and an integrator are combined. For example, JP-A-8-
In Japanese Patent No. 234205, a polarization separation film is provided between a right-angle prism and a tapered glass plate, a reflection film is provided on the opposite side of the tapered glass plate, and an incident-side lens array is arranged on the exit side of the right-angle prism. There is disclosed a polarization beam splitter configured so that the emitted light is incident on the emission-side lens array. However, this polarization separation device has a problem in that the right-angle prism becomes considerably large, so that the cost is high. Also, the tapered glass plate may be 2
Since the light paths of the two polarized light components have different optical path differences, a region where the light of the two polarized light components cannot be separated well occurs on the exit-side lens array, and there is a problem that the efficiency is not very high.

In Japanese Patent Application Laid-Open No. 8-234205, a polarizing beam splitter in which a plurality of prism elements are combined in a plate shape is used to split natural light emitted from a light source into two polarized light components whose polarization directions are orthogonal to each other. There is also disclosed a configuration in which light of these two polarization components is emitted in different directions so that light of these two polarization components passes through different positions of each positive lens element of the emission-side lens array. However, this polarization separation device has a problem that the configuration of the device is complicated and it is difficult to assemble the device.

Japanese Patent Application Laid-Open No. 6-202094 discloses a polarization conversion optical system in which a thin polarization separation element in which a material having a refractive index anisotropy is bonded to a sawtooth prism array substrate and an integrator are combined. Have been. Since the difference in the refractive index of the boundary surface varies depending on the polarization direction, the polarization separation element can shift the traveling direction of the emitted light beam between the ordinary light beam and the extraordinary light beam. However, in the case of this polarization separation element, there is a problem that there is no easy-to-use refractive index anisotropic material.

In addition, a polarizing beam splitter is disposed immediately after the light source to separate natural light emitted from the light source into two linearly polarized light components, one of which is a half-wave plate or a 90 ° T.
The polarization plane is rotated by 90 degrees by N liquid crystal, the traveling direction of the ray is made parallel to the traveling direction of the other ray, and a polarization conversion optical system (for example,
JP-A-63-271313, JP-A-63-168
No. 622) has been proposed. Further, a polarization conversion optical system using two plane mirrors (for example,
197913) has also been proposed. However, any of the polarization separation devices has a problem that the efficiency is not so much improved when combined with an integrator because the optical path length is long. There was also a problem that the whole set became large.

The present invention relates to a polarized light separating device for separating natural light into two linearly polarized lights having different traveling directions, a polarized light illuminating device having high efficiency and good illuminance uniformity using the polarized light separating device,
An object of the present invention is to provide a projection type display device that displays a projected image that is compact, bright and has good illuminance uniformity using the polarized light illumination device. Another object of the present invention is to provide a method for manufacturing the above-described polarization separation device.

[0012]

SUMMARY OF THE INVENTION In order to solve this problem, a polarization separation device according to the present invention includes a prism array in which a plurality of prisms each having a quadrangular cross section are arranged, and adjacent prisms in the prism array have inclined surfaces. The adjacent prisms are configured to have opposite refractive indices, and the adjacent prisms are configured to have different refractive indices. The polarization separation film that separates natural light into two polarized light components having polarization directions orthogonal to each other is provided by the polarization separation film. It is configured to be sandwiched between slopes.

A polarized light illuminating device according to the present invention comprises: a light source for emitting natural light; and a polarization splitting device for emitting light of two polarized components, in which the emitted light from the light source is incident and whose polarization directions are orthogonal to each other, in different directions. And a polarization direction correcting means for converting the light of the two polarization components into light having the same polarization direction, wherein the polarization separation device is the polarization separation device according to any one of claims 1 to 6. The polarization direction correcting means rotates one polarization direction of the two polarization components by a predetermined angle including zero, and changes the other polarization direction by one polarization rotated by a predetermined angle including the zero. By rotating by 90 ° with respect to the direction, it is possible to irradiate the irradiated area with light close to linearly polarized light.

Further, the polarized light illuminating device of the present invention has an incident lens array disposed near the entrance side or the exit side of the polarized light separating device, and an outgoing beam from which the emitted light from the polarized light separating device or the incident side lens array enters. And a polarization direction correcting means, which is disposed near the incident side or the outgoing side of the outgoing side lens array, and wherein the incoming side lens array is a two-dimensional array of a plurality of incoming side lens elements. The emission-side lens array includes a plurality of emission-side lens elements that form a pair with the incidence-side lens elements, and are two-dimensionally arranged. The two polarized light components corresponding to the respective incidence-side lens elements are The exit-side lens element is configured to converge to a different position in the opening of each of the exit-side lens elements, and the exit-side lens element forms a real image of the aperture of the entrance-side lens element in the irradiated area. In which was to so that.

The projection display device of the present invention includes the above-described polarized light illuminating device for irradiating the region to be illuminated with light close to linearly polarized light, a light valve for receiving light emitted from the polarized light illuminating device and forming an optical image, And a projection lens that receives the light emitted from the light valve and projects the optical image.

According to the method of manufacturing a polarized light separating apparatus of the present invention, a plurality of transparent flat plates of a first material and a plurality of transparent flat plates of a second material having a different refractive index from the first material have a predetermined thickness. A second step of applying a polarization separation film to the transparent flat plate of the first material and the transparent flat plate of the second material; and a transparent flat plate of the plurality of first materials and a plurality of transparent flat plates of the second material. Second
A third step of forming a first combined body by adhering with a transparent adhesive such that transparent flat plates of the material are alternately overlapped, and forming the first combined body into a plurality at a predetermined angle with respect to a joint surface. A fourth step of cutting and polishing the cut surface to form a plurality of second combined bodies;
And the steps of

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. (Embodiment 1) FIGS. 1 and 2 show a configuration of a polarization beam splitting device based on Embodiment 1 of the present invention.
In these figures, 41 is a first prism and 43 is a second prism, each having a parallelogram cross section. A polarization separating film 42 is deposited on the slope of the first prism 41 and the second prism 43 is connected to a transparent adhesive 46.
Thus, the polarization separation element 45 is formed. Then, a plurality of polarized light separating elements 45 are bonded in a line with a transparent adhesive. The polarization separation film 42
A low refractive index film and a high refractive index film are alternately laminated. The refractive index of the first prism 43 is
, And the refractive index of the transparent adhesive 46 is slightly lower than the refractive index of the second prism 44. The entrance side surfaces 47 of the first prism 41 and the second prism are all flush, and the exit side surfaces 48 are all flush. Antireflection films 49 and 50 are deposited on the entrance side surface 47 and the exit side surface 48, respectively.

The operation of this polarization separation device will be described with reference to FIG. Natural light incident on the polarization separation device along the optical axis 52 is divided into a light beam incident on the first prism 41 and a light beam incident on the second prism 43. The light beam 51 transmitted through the first prism 41 is incident on the polarization splitting film 42. The polarization splitting film 42 transmits most of the P-polarized light component,
Most of the S-polarized component is reflected. Second prism 43
Is lower than the refractive index of the first prism 41,
The light 53 of the P-polarized component is in a direction 54 oblique to the optical axis 52.
Exit along. Since the polarization splitting films 42 are arranged in parallel with each other, the S-polarized light component 55
2 and further reflected by another adjacent polarization splitting film 42 and emitted parallel to the optical axis 52. Thus, the P-polarized component light 53 and the S-polarized component light 55
Are out of parallel with each other.

Similarly, the natural light 56 incident on the second prism 43 is transmitted through the second prism 43 and is incident on the polarization splitting film 42. The polarization splitting film 42 transmits most of the P-polarized light component and reflects most of the S-polarized light component. Second
Since the refractive index of the prism 43 is lower than the refractive index of the first prism 41, the P-polarized component light 57 is emitted along the direction 59 oblique to the optical axis 52. Since the polarization separation films 42 are arranged in parallel with each other, the light 58 of the S-polarized light component
Are reflected by the polarization separation film 42, further reflected by another adjacent polarization separation film 42, and emitted parallel to the optical axis 52.
Thus, the P-polarized component light 57 and S
The light 58 of the polarized light component is emitted in a state of being shifted from the parallel state.

At this time, the P-polarized component light 57 emitted from the first prism 41 and the P-polarized component light 53 emitted from the second prism 43 are separated from the first prism 41 and the second
Since the directions of refraction at the joint surface with the prism 43 are different from each other, the directions of emission from each other are different. If the difference between the refractive index of the first prism 41 and the refractive index of the second prism 43 is small, P
The angle formed by the polarization component light 57 with the optical axis 52 is substantially equal to the angle formed by the P polarization component light 53 emitted from the second prism 43 with the optical axis 52.

A part of the S-polarized light component reflected by the polarization splitting film 42 and traveling along the direction perpendicular to the optical axis 52 is incident on another adjacent polarization splitting film 42. Since the angle between the film 42 and the optical axis 52 is 45 °, the S-polarized light beams 55 and 58 emitted from the polarization separation device and the optical axis 5
The angle between 2 is the same as the angle between the incident natural light 51 and the optical axis 52.

Thus, the polarization beam splitter shown in FIG.
The incident natural light can be efficiently separated into S-polarized light and P-polarized light. In order to increase the efficiency, the entrance side surface 47 and the exit side surface 4 of each prism 41, 43 are required.
8 and 8 may be aligned on one plane.

The refractive index of the first prism 41 is n ₁ ,
Assuming that the refractive index of the prism 43 is n ₂ and the refractive index of the transparent adhesive 46 is n _A , the first prism 41 and the transparent adhesive 4
6, the total reflection critical angle θ _1T of the surface in contact with the second prism 4
3 is the critical angle of total reflection θ _{2T of the} surface where transparent adhesive 46 contacts
Is as follows:

N ₁ · sin θ _1T = n _A (1) n ₂ · sin θ _2T = n _A (2) Using equations (1) and (2), all effective light is totally reflected. What is necessary is just to make the refractive index n _A of the transparent adhesive 46 slightly lower than the refractive index n ₂ of the second prism 43.
The difference between the refractive index n ₂ of the refractive index n _A and the second prism 43 of transparent adhesive 46 in this case is too large, the transmittance for P-polarized light component is reduced slightly as described above It is good to lower.

Increasing the number of the polarization separation elements 45 can make the polarization separation device thinner. This is very convenient when a polarization separation device and an integrator are combined as described later.

The polarization separation characteristics of the polarization separation film 42 will be described. When the incident angle and the refraction angle are Brewster's angles at the interface between the layers constituting the polarization separating film 42 having a laminated structure, the transmittance of the P-polarized light component at one interface is ideally 1
00%, and the transmittance of the S-polarized light component is lower than 100%. Therefore, if the number of layers of the polarization separation film 42 having a laminated structure is increased, the P-polarized light transmittance is set to a value close to 100%,
In addition, the S-polarized light transmittance can be extremely reduced. Further, by optimizing the thickness of each layer of the polarization separation film 42, the S-polarized light reflectance can be made close to 100% by utilizing light interference.

The reference incident angle in the first prism 41 (the angle between the normal to the polarization separation film 42 and the optical axis 52) is θ ₁ , the reference emission angle in the second prism 43 is θ ₂ , and the polarization separation is performed. The refractive index of the high refractive index layer in the film 42 is represented by n
_H , the refractive index of the low refractive index layer is n _L , the refractive angle of the high refractive index layer is θ _H , and the refractive index of the low refractive index layer is θ _L.
Using a refractive index n ₁ of the prism 41 and the refractive index n ₂ of the second prism 43, the following relationship holds according to Snell's law.

N ₁ · sin θ ₁ = n _H · sin θ _H = n _L · sin θ _L = n ₂ · sin θ ₂ (3) The incident angle and the refraction angle are Brewster's angles at the interface between the layers forming the polarization separation film 42. In order to satisfy the condition, the following conditions must be satisfied.

N ₁ · tan θ ₁ = n _H (4) n _H · tan θ _H = n _L (5) From the equations (3), (4) and (5), the following equation is obtained.

[0030]

(Equation 1)

As described above, since the first prism 41 is desirably a parallelogram, when an incident light beam enters the polarization separation device along the optical axis 52, the polarization separation in the incident side prism 41 is performed. The angle of incidence on the film 42 is θ ₁ = 45
°. Therefore, when θ ₁ = 45 ° is substituted into the equation (6), the following is obtained.

[0032]

(Equation 2)

Since it is more advantageous to increase the value of n _H / n _L to widen the wavelength band of the high reflectance band of the S-polarized light, the refractive index n _L of the low refractive index layer should be as low as possible and the high refractive index should be high. The refractive index n _H of the refractive index layer should be as high as possible. As the low refractive index layer, magnesium fluoride (MgF ₂ : refractive index at e-line 1.39), silicon dioxide (Si
O ₂ : e-line refractive index 1.46). As the high refractive index layer, tantalum pentoxide (Ta ₂ O ₅ : refractive index at e-line 2.00), titanium dioxide (TiO ₂ :
The refractive index at e-line is 2.25). By substituting n _L and n _H into the equation (7), the optimum refractive index n _{1 of} the first prism 41 is obtained. Using this refractive index n ₁ and the expressions at both ends of the expression (3), the refractive index n ₂ of the second prism 43 is obtained.
And the refraction angle θ ₂ in the second prism 43 are determined.

Similarly, for the light beam 56 that passes through the second prism 43 and enters the polarization separation film 42, the refractive index,
A refraction angle is required. Note that the spectral transmittance characteristic of the polarization separation film 42 for S-polarized light is such that the light is
1 is different from the case where the light is incident on the polarization splitting film 42 from the second prism 43. This occurs because the first prism 41 and the second prism 43 have different refractive indices, although the angles of incidence when entering the polarization separation film 42 are the same. That is, the wavelength band of the latter high reflectance band of S-polarized light reflectance is shifted to a longer wavelength side than that of the former. Since the product of the former S-polarized light reflectance and the latter S-polarized light reflectance is dominant for the transmission efficiency of the S-polarized light to the S-polarized light, the wavelength band of the high reflectance band of both S-polarized light reflectance is obtained. Need to be a little wider.

Next, a specific example of the polarization separation device shown in FIGS. 1 to 3 will be described. External dimensions are 70mm x 70m
m and five parallelogram-shaped prisms 41 and 43 each having a short-side length of 7 mm. The first prism 41 is an optical glass SSK5 manufactured by Schott (refractive index n ₁ = 1.662 at e-line), and the second prism 43
Was optical glass BaK4 (refractive index n ₂ = 1.571 at e-line) manufactured by SCHOTT. In consideration of the stress and performance stability of the polarization separation film 42, the polarization separation film 42 was made of silicon dioxide as the low refractive index film and tantalum pentoxide as the high refractive index film. The transparent adhesive 46 has a refractive index of 1.5
3 UV curable adhesive was used.

When a light beam enters the first prism 41 perpendicularly from the air, the incident angle on the polarization separation film 42 in the first prism 41 is θ ₁ = 45 °, and the refraction in the second prism 43 The angle was θ ₂ = 48.4 °, and the light beam was bent by 3.4 ° before and after the polarization separation film 42. Further, the incident angle on the exit side surface 48 was 3.4 ° and the refraction angle was 5.4 °. Therefore, the light of the S-polarized component and the light of the P-polarized component could be emitted in directions different by 5.4 °.

Similarly, when a light beam is perpendicularly incident on the second prism 43 from the air, the incident angle on the polarization separation film 42 in the second prism 43 is θ ₁ = 45 °, and the first prism 41 The refraction angle in the inside was θ ₂ = 41.9 °, and the light beam was bent by 3.1 ° before and after the polarization separation film. Further, the incident angle on the exit side surface 48 was 3.1 ° and the refraction angle was 5.1 °. Therefore, the light of the S polarization component and P
The light of the polarization component could be emitted in a direction different by 5.1 °.

As described above, the P-polarized light component emitted from the first prism 41 and the P-polarized light component emitted from the second prism 43 are emitted in directions substantially symmetric with respect to the optical axis.
Using the expressions (1) and (2), when the refractive index of the transparent adhesive 46 is 1.53, θ _1T = 67.0 ° and θ _2T = 7.
6.9 °, which is large enough to totally reflect light incident on the boundary surface.

Polarized light separating film 4 having a multilayer structure composed of multilayer films
Table 1 shows a configuration example of No. 2. FIG. 4 shows the spectral transmittance characteristics of the polarization separation film 42 shown in Table 1.

[0040]

[Table 1]

In FIG. 4, the dotted line indicates that the incident angle is θ ₁ = 45.
The transmittance of P-polarized light in the case of °, the broken line indicates that the incident angle is θ ₁ = 45.
The reflectance of S-polarized light in the case of °, the solid line indicates that the incident angle is θ ₂ = 45.
This is the reflectance of S-polarized light in the case of °.

Table 2 shows an example of the configuration of the antireflection film 49 applied to the incident side surface 47 and the antireflection film 50 applied to the output side surface 48.

[0043]

[Table 2]

[0044] Since the difference between the refractive index n ₁ of 41 of the first prism as described above (= 1.662) and the refractive index n ₂ of the second prism 43 (= 1.571) is not greater, wherein The antireflection films 49 and 50 on both sides have the same configuration.

FIG. 5 shows the spectral characteristics of the transmission efficiency of the polarization beam splitter when linearly polarized light enters the first prism 41 from the air along the optical axis 52. In FIG. 5, the solid line represents the characteristic of S-polarized light, and the dotted line represents the characteristic of P-polarized light. For S-polarized light, the transmittance of each of the two types of antireflection films 49 and 50, the S-polarized light reflectance of the polarization splitting film 42 when entering from the first prism 41, and the S-polarized light when entering from the second prism 43 And the S-polarized light reflectance of the polarization separation film 42 of FIG. For P-polarized light, two types of antireflection films 49, 5
0 and the P-polarized light transmittance of the polarization splitting film 42. FIG. 5 shows that the transmission efficiency of the polarization separation device is high.

As can be seen from the above description and FIG.
The above-mentioned polarization separation device can efficiently emit the S-polarized light component and the P-polarized light component in slightly different directions when natural light is incident thereon.
The optical path difference between the polarization component and the P polarization component can be reduced.

Hereinafter, a method of manufacturing the polarization beam splitter shown in FIG. 1 will be described with reference to FIGS. In FIGS. 6 to 10, a member with hatching indicates a high refractive index glass member, and a member without hatching indicates a low refractive index glass member. The polarization separation film 42 and the transparent adhesive 4
The illustration of 6 is omitted.

(1) First, a plurality of high refractive index glass plates 251 having a refractive index suitable for the first prism 41 and a second
A plurality of low-refractive-index glass plates 252 having a refractive index suitable for the prism 43 are prepared, all are processed to have the same thickness, and both surfaces are polished.

(2) Next, as shown in FIG. 6, a polarization separation film 253 is deposited on one surface of each of the high refractive index glass plate 251 and the low refractive index glass plate 252. (3) As shown in FIG. 7, the high-refractive-index glass plate 251 and the low-refractive-index glass plate 252 alternately overlap, and the high-refractive-index glass plate 251 and the low-refractive-index glass plate 253 are sandwiched therebetween. The first bonded body 255 is created by sequentially bonding the rate glass plate 252 with a transparent adhesive. When bonding, the adjacent glass plates 251 and 252 are shifted from each other by an amount corresponding to the thickness thereof, thereby reducing waste. As the glass plate located at one end, a glass plate to which the polarization separation film 253 is not attached can be used.

(4) As shown in FIG. 8, the first conjugate 2
55 is cut into a plurality of pieces at a plane that forms an angle of 45 ° with respect to the bonding surface, processed into a predetermined thickness, and then polished on both sides to form a second bonded body 256.

(5) As shown in FIG. 9, the second conjugate 2
The both ends of 56 are cut at a plane perpendicular to the polished surfaces to form a third combined body 257. (6) As shown in FIG. 10, anti-reflection films 49, 5 are provided on the incident side surface 47 and the output side surface 48 of the third combined body 257, respectively.
0 is deposited.

When this manufacturing method is used, the ridge line of each prism can be processed into a clean edge even if the thickness in the optical axis direction is small, so that the ineffective area can be made very small and mass productivity can be improved. good.

(Embodiment 2) FIG. 11 shows a configuration of a polarized light illuminating apparatus based on Embodiment 2 of the present invention. This polarized light illuminating device includes a light source 61 and a polarized light separating device 6.
2, an incidence-side lens array 63, an emission-side lens array 64, a polarization direction correction plate 65, and a positive lens 66, and illuminates an irradiation area 67 arranged at a predetermined position. . Also, the incident side lens array 63,
The exit side lens array 64 and the positive lens 66 constitute an integrator.

The light source 61 includes a lamp 68 and a concave mirror 69.
And a filter 70. The concave mirror 69 is a parabolic mirror, and is formed by depositing an optical multilayer film that reflects visible light and transmits infrared light on the inner surface of a glass substrate. The lamp 68 is arranged such that the center of the illuminant is the focal point 7 of the concave mirror 69.
2 are arranged. The filter 70 is
An optical multilayer film that transmits visible light and reflects infrared light and ultraviolet light is deposited on one surface of a glass substrate, and an antireflection film is deposited on the other surface. The natural light radiated from the lamp 68 is converted into near parallel light by the concave mirror 69 and only visible light is transmitted by the filter 70.
The light enters the polarization separation device 62. The polarization separation device 62 has the same configuration as the polarization separation device shown in FIGS.

When light close to parallel light emitted from the light source 61 is incident on the polarization separation device 62 along the optical axis 75, S-polarized light 76 is emitted along the optical axis 75 and P-polarized light 77 is converted into light. A direction inclined from the axis 75 by an angle α (not shown);
The light is emitted along a direction inclined by an angle β (not shown). Both the S-polarized light 76 and the P-polarized light 77 exit in different directions while being nearly parallel light, and both enter the incident-side lens array 63.

The incident-side lens array 63 is formed by arranging a plurality of incident-side lens elements 78 functioning as positive lenses on the incident side surface, and each lens element 78 has a shape similar to the effective area of the irradiated area 67 and is all the same. The dimensions are as follows. The emission-side lens array 64 has a plurality of emission-side lens elements 79 that function as positive lenses arranged on the emission side surface.

The focal point of the entrance lens element 78 is located near the corresponding exit lens element 79. The focal length of each exit lens element 79 is
Is set such that an image of the opening is formed on the irradiation area 67. The incident-side lens array 63 has a direction in which the traveling direction of the S-polarized light 76 and the traveling direction of the P-polarized light 77 emitted from the polarization splitting device 62 are equally divided into two. Each optical axis 87 is parallel to the center of each aperture so as to be parallel to the optical axis 80 at 78.
Are eccentrically arranged.

Both the S-polarized light 76 and the P-polarized light 77 emitted from the polarization separation device 62 enter each of the incident side lens elements 78, and are placed on the exit side lens element 79 by the lamp 6.
Each real image corresponding to 8 light-emitting bodies is formed. Since both the S-polarized light 76 and the P-polarized light 77 are incident from an oblique direction with respect to the optical axis 80 of the incident side lens element 78, on the exit side lens element 79, the centers thereof are opposite to each other. A real image corresponding to the illuminant of the lamp 68 is formed at a distant position. In the exit lens disposed adjacent to the polarization separation film 42 in the plane direction perpendicular to each polarization separation film 42 of the polarization separation device 62, the positions of the real image of the light emitter of the lamp 68 by P-polarized light and the real image of the light emitter by S-polarized light are reversed. I do.

The polarization direction correction plate 65 is arranged near the exit side of the exit side lens array 64. The polarization direction correcting plate 65 has a half-wave plate 83 attached only to a region through which S-polarized light passes. The polarization direction of the S-polarized light emitted from each emission-side lens element 79 is rotated by 90 ° by the half-wave plate 83, and the P-polarized light emitted from each emission-side lens element 79 is changed to the half-wave plate 83. After passing through the polarization direction correction plate 65, the light becomes almost linearly polarized light having a uniform polarization direction. Each emission-side lens element 79 attempts to form an enlarged real image of the aperture of the corresponding entrance-side lens element 78 in the irradiated area 67.

The positive lens 66 is arranged near the emission side of the emission-side lens array 64, and the focal length of the positive lens 66 is set so that its focal point is located near the irradiation area 67. Therefore, the enlarged images of the apertures of the respective incident-side lens elements 78 formed by the respective exit-side lens elements 79 substantially overlap each other on the irradiated region 67. The luminance distribution in each incident-side lens element 78 is determined by the incident-side lens array 6.
Since the change is smaller than the luminance distribution in 3, the illuminance distribution becomes flat on the irradiated area 67.

The width of the effective area of each incident-side lens element 78 of the incident-side lens array 63 is substantially equal to the width of the effective area of the exit side of each prism of the polarization beam splitter 62. Thus, even if the end of the first prism 41 or the second prism 43 of the polarization separation device 62 is damaged during polishing, a negative image due to the loss is less likely to be formed inside the illuminated area 67, and there is no unevenness. Lighting is obtained.

Each of the prisms 41 and 43 of the polarization separation device 62
Are arranged horizontally, the effective width of the effective area of each of the prisms 41 and 43 and the effective area of the incident-side lens element 78 of the incident-side lens array 63 may be substantially equal.

As described above, by using the polarized light illuminating apparatus of the present invention, it is possible to efficiently irradiate the irradiated area 67 with light having a uniform illuminance distribution and nearly linearly polarized light. 1 /
As the two-wavelength plate 83, an optical crystal, a stretched resin film, or the like can be used. Since an optical crystal is expensive, a stretched resin film is preferably used. Since the stretched resin film has a low upper-limit temperature for use, it is preferable to forcibly cool it with a cooling fan if necessary.

The polarization direction correcting plate 65 may have a half-wave plate attached to both the region through which the S-polarized light passes and the region through which the P-polarized light passes. In this case, the former half-wave plate rotates the polarization direction by an angle α, and the latter half-wave plate rotates the polarization direction by (α + 90 °) or (α−90 °). It is necessary to set the direction of the slow axis of the half-wave plate to a predetermined direction.

Instead of using the polarization direction correcting plate 65, a half-wave plate may be attached to the plane on the incident side or the exit side of each exit side lens element 79 of the exit side lens array 64.
If the transparent adhesive used for the polarization separation device 62 is used at a temperature exceeding the upper limit temperature, the transmittance is lowered or peeling is caused. When the light output of the light source is large, the polarization separation device 62 may be forcibly cooled by a cooling fan.

In the configuration shown in FIG. 11, the incident-side lens array 63 is configured such that the incident side is a flat surface and the outgoing side is a lens surface.
May be joined with a transparent adhesive. This eliminates the need to form an anti-reflection film on the exit side of the polarization separation device 62 and the incidence side of the incidence side lens array 63, and can reduce the cost.

(Embodiment 3) FIG. 12 shows a configuration of a polarized light illuminating apparatus according to Embodiment 3 of the present invention. This polarized light illuminating device is different from the polarized light illuminating device shown in FIG.
Is basically different from the polarized light illumination device shown in FIG.

The configuration of the light source 91 is the same as that of the light source 6 shown in FIG.
1 is the same as that of FIG. Natural light emitted from the light source 91 is transmitted through the incident-side lens array 92, the polarization separation device 93, the emission-side lens array 94, and the positive lens 96 in this order, and reaches the irradiated area 97. The incident side lens array 92
Similar to the incident-side lens array 63 shown in FIG. 11, a plurality of incident-side lens elements 98 functioning as positive lenses are arranged on the incident side surface. Each lens element 98 has a shape similar to the effective area of the irradiated area 97 and all have the same dimensions. The polarization beam splitter 93 has the same configuration as the polarization beam splitter shown in FIG. 1 to FIG. 3. When natural light emitted from the incident side lens array 92 enters, the S-polarized light 99 and P
The polarized light 100 exits in different directions. The emission-side lens array 94 includes the emission-side lens array 64 shown in FIG.
Similarly, the emission-side lens element 1 that functions as a positive lens
01 are arranged on the output side surface. The horizontal pitch of the entrance-side lens array 92 and the horizontal pitch of the exit-side lens array 94 are equal to each other, the optical axes of the entrance-side lens elements 98 are parallel to each other, and the optical axes of the exit-side lens elements 101 are also parallel. is there. Each emission side lens element 1
The optical axis of 01 is eccentric with respect to the center of the opening by ／ of the horizontal pitch of the exit lens array 94. The direction of the eccentricity is opposite for each adjacent lens. The focal point of the entrance-side lens element 98 is located near the corresponding exit-side lens element 101, the focal point of each exit-side lens element 101 is located near the corresponding entrance-side lens element 98, and the focal point of the positive lens 96 is covered. It is located near the irradiation area 97.

On the incident side of the exit side lens array 94, S
波長 wavelength plate 104 only in the region where polarized light 99 passes
Is attached, and this S-polarized light 99 is a half-wave plate 1
04 rotates the polarization direction by 90 °.

The natural light emitted from the light source 91 is
When the light enters the incidence-side lens array 92 through the zero-emission-side lens element 101,
Above, an attempt is made to form a real image of the illuminant of the lamp 68 constituting the light source 91. When the natural light emitted from the incidence-side lens array 92 enters the polarization separation device 93, the S-polarized light 99 travels along the optical axis 75, and the P-polarized light 100 travels in a direction deviated from the optical axis 75. Side lens element 101
A real image corresponding to the illuminant of the lamp 68 is formed thereon.

The polarization direction of the S-polarized light 99 is rotated by 90 ° by the half-wave plate 104, and the P-polarized light 100 does not pass through the half-wave plate 104. Light that is close to linearly polarized light whose direction is aligned is incident. The light of the two polarization components is transmitted to each of the exit lens elements 10.
Due to 1, the light is emitted in parallel with the optical axis 75 and enters the positive lens 96. Each exit-side lens element 101 forms a magnified real image of the aperture of the corresponding entrance-side lens element 98 so as to overlap each other at infinity, and the positive lens 96 irradiates a corresponding image using the real image at infinity as an object. Area 9
7. Therefore, each output-side lens element 101
The enlarged images of the apertures of the respective incident-side lens elements 98 formed by the above overlap on the irradiated area 97. The luminance distribution in each incident-side lens element 98 is determined by the incident-side lens array 92.
Since the change is small compared to the luminance distribution in the
7, the illuminance distribution becomes flat.

The lateral width of each incident-side lens element 98 of the incident-side lens array 92 is substantially equal to the lateral width of the exit-side effective area of each prism of the polarization beam splitter 93. Accordingly, even if the end of the first prism 41 or the second prism 43 of the polarization separation device 93 is lost during polishing, a negative image due to the loss is less likely to be formed inside the illuminated area 97, and there is no unevenness. Lighting is obtained. Each prism 41, 4 of the polarization separation device 93
3 is arranged horizontally, each prism 41, 43
And the vertical width of the incident side lens 98 of the incident side lens array 93 should be substantially equal.

As described above, by using the polarized light illuminating device of the present invention, it is possible to efficiently irradiate the irradiated area 97 with light having a uniform illuminance distribution and near linear polarization. In the configuration shown in FIG. 12, the incident-side lens array 92 and the polarization separation device 93 may be joined by a transparent adhesive. This eliminates the need to form an anti-reflection film on the exit side of the entrance-side lens array 92 and the incidence side of the polarization beam splitter 93, and can reduce the cost.

(Embodiment 4) FIG. 13 shows the configuration of a projection display apparatus according to Embodiment 4 of the present invention. Here, the polarized light illuminating device 121 is the same as that shown in FIG. 11, and includes a light source 61, a polarized light separating device 62, an incident side lens array 63, an exit side lens array 64,
It comprises a polarization direction correction plate 65 and a positive lens 66. 68 is a lamp, 69 is a concave mirror, and 70 is a filter.

The light emitted from the polarization illuminating device 121 enters a color separation optical system composed of a blue reflection dichroic mirror 122, a red reflection dichroic mirror 123, and a plane mirror 124, and emits red, green and blue primary colors. Decomposed into light. Each primary color light emitted from the color separation optical system passes through the field lenses 126, 127, 128 and the incident side polarizing plates 129, 130, 131, and then enters the liquid crystal panels 132, 133, 134. Each of the three liquid crystal panels 132, 133, and 134 is a TN liquid crystal panel, and forms an optical image as a change in polarization state. Each of the liquid crystal panels 132, 133, 134 from the polarized light illumination device 121
The optical path length is the same for each of the red, green, and blue optical paths, and the respective polarization axes of the incident-side polarizing plates 129, 130, and 131 coincide with the central polarization direction of the linearly polarized light emitted from the polarization illumination device 121. I have.

Light emitted from each of the liquid crystal panels 132, 133, and 134 is output to the output-side polarizing plates 135, 136, and 1, respectively.
37, and a red reflecting dichroic mirror 138;
Green reflection dichroic mirror 139 and flat mirror 14
The light enters the color combining optical system composed of 0 and is combined into one light, and then enters the projection lens 142. Thus,
The optical images formed on the liquid crystal panels 132, 133, and 134 are enlarged and projected on the screen.

The projection type display device shown in FIG. 13 includes a polarization separation device 62, an entrance side lens array 63, an exit side lens array 64, a polarization direction correction plate 65, and a positive lens 66 in the polarization illumination device 121. , Natural light emitted from the light source 61 is efficiently converted to light close to linearly polarized light, and the light close to linearly polarized light is
Since 9, 130, and 131 are transmitted with high transmittance, the efficiency is very high. Also, the incident side polarizing plates 129, 130, 1
Since light close to linearly polarized light is incident on 31, there is an advantage that light absorption by these incident-side polarizing plates 129, 130, and 131 is small, and the reliability is increased accordingly. Furthermore, the incident side lens array 63 and the exit side lens array 64 in the polarized light illumination device 121 can improve the uniformity of the illuminance of the projected image.

(Embodiment 5) FIG. 14 shows a configuration of a projection type display apparatus based on Embodiment 5 of the present invention. Here, the polarization illumination device 151 is the same as that shown in FIG. 11, and includes a light source 61, a polarization separation device 62, an incidence-side lens array 63, an emission-side lens array 64, a polarization direction correction plate 65, And a lens 66. 68 is a lamp, 69 is a concave mirror, and 70 is a filter.

The light emitted from the polarized light illuminating device 151 is reflected by a plane mirror 152 and then transmitted through a blue transmitting dichroic mirror 153, a green reflecting dichroic mirror 154,
The light enters the color separation optical system constituted by the plane mirror 155 and is separated into red, green and blue primary color lights. The red primary color light
The first relay lens 156 and the second relay lens 15
7 and two relay mirrors 158 and 159. The blue and green primary color lights emitted from the color separation optical system and the red primary color light emitted from the relay optical system are respectively divided into field lenses 160, 161 and 16 respectively.
After passing through the incident-side polarizing plates 163, 164, and 165, the light enters the liquid crystal panels 166, 167, and 168.

The three liquid crystal panels 166, 167, 168
Are TN liquid crystal panels, each of which forms an optical image as a change in polarization state. Incident side polarizing plates 163, 164,
Each polarization axis of 165 coincides with the central polarization direction of light close to linearly polarized light emitted from the polarized light illumination device 151.

The light emitted from each of the liquid crystal panels 166, 167, and 168 is output from the output side polarizing plate 169, 170, respectively.
The light passes through 171 and enters the color combining prism 172. The color synthesizing prism 172 is formed by joining four triangular prisms such that a red reflection dichroic multilayer film and a blue reflection dichroic multilayer film are arranged in an X-shape on a slope. Each primary color light incident on the color combining prism 172 is combined into one light by the color combining prism 172,
The light enters the projection lens 173. Liquid crystal panels 166, 16
The optical images formed on 7 and 168 are enlarged and projected on a screen by a projection lens 173.

In the configuration shown in FIG.
Since the optical path length from 51 to each of the liquid crystal panels 166, 167, 168 is longer only in the red optical path than in the other optical paths, care must be taken to effectively obtain the operation of the polarized light illuminating device 151.
In the configuration shown in FIG. 14, the equivalent optical path length of red is made equal to the optical path lengths of green and blue by the relay optical system.

This point will be described a little more. When the polarized illumination device 151 emits light that is nearly parallel and the projection lens 173 is telecentric, the focal point of the first relay lens 156 is located near the second relay lens 157, and the second relay lens The focal length of the lens 157 is changed from the first relay lens 156 to the second relay lens 15.
7 is substantially equal to the optical path length, and the second relay lens 15
7 is substantially equal to the optical path length from the first relay lens 156 to the second relay lens 157, and the focal point of the field lens 162 is located near the second relay lens 157. Good to do.

Thus, the image of the illuminant of the lamp 68 constituting the light source 61 is changed to the second relay lens 156 by the second relay lens 156.
Of the object near the first relay lens 156 is formed near the field lens 162 by the second relay lens 157. The illuminance and the illuminance distribution are close to the average illuminance and the illuminance distribution near the incident side of the first relay lens 156. Thus, the optical path lengths from the polarization illuminator 151 to the red, green, and blue liquid crystal panels 166, 167, and 168 are equivalently equalized by the relay optical system, and the operation of the polarization illuminator of the present invention can be effectively obtained. Can be.

The projection type display device shown in FIG.
The same effects as those of the projection display device shown in FIG.

[0086]

As described above, according to the present invention, inexpensive,
A thin polarization separator having a small optical path difference between the S-polarized component and the P-polarized component can be provided, and a low-cost, high-productivity manufacturing method of the polarized light separator can be provided. In addition, it is possible to provide a polarized light illuminating device with high efficiency and good illuminance uniformity of an irradiation area, and to provide a projection display device with high efficiency and good illuminance uniformity of a projected image.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a polarization beam splitter according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part showing a configuration of the polarization beam splitter of FIG.

FIG. 3 is an explanatory diagram for explaining an operation of the polarization separation device of FIGS. 1 and 2;

FIG. 4 is a characteristic diagram showing a spectral transmittance characteristic of a polarization splitting film in a specific example of the polarization splitting device of FIGS.

FIG. 5 is a characteristic diagram showing a total spectral transmittance characteristic in a specific example of the polarization separation device.

FIG. 6 is a schematic configuration diagram illustrating a method of manufacturing the polarization separation device of FIGS.

FIG. 7 is a schematic configuration diagram illustrating a step subsequent to FIG. 6 in the manufacturing method.

FIG. 8 is a schematic configuration diagram illustrating a step subsequent to FIG. 7 in the same manufacturing method.

FIG. 9 is a schematic configuration diagram illustrating a step subsequent to FIG. 8 in the same manufacturing method.

FIG. 10 is a schematic configuration diagram illustrating a step subsequent to FIG. 9 in the same manufacturing method.

FIG. 11 is a schematic diagram illustrating a configuration of a polarized light illumination device according to a second embodiment of the present invention.

FIG. 12 is a schematic diagram illustrating a configuration of a polarized light illumination device according to a third embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating a configuration of a projection display apparatus according to a fourth embodiment of the present invention.

FIG. 14 is a schematic diagram illustrating a configuration of a projection display apparatus according to a fifth embodiment of the present invention.

FIG. 15 is a schematic configuration diagram illustrating an example of a conventional projection display device.

[Explanation of symbols]

41 First Prism 42 Polarization Separation Film 43 Second Prism 45 Polarization Separation Element 46 Transparent Adhesive 49, 50 Antireflection Film 251 High Refractive Index Glass Plate 252 Low Refractive Index Glass Plate 253 Polarization Separation Film 255 First Combined Body 256 Second combined body 257 Third combined body 61, 91 Light source 62, 93 Polarization separation device 63, 92 Incident side lens array 64, 94 Outgoing side lens array 65 Polarization direction correction plate 66, 96 Positive lens 67, 97 Irradiation area 68 Lamp 69 Concave mirror 70 Filter 121, 151 Polarized illumination device 132, 133, 134, 166, 167, 168 Liquid crystal panel 126, 127, 128, 160, 161, 162 Field lens 129, 130, 131, 163, 164, 165 Incident-side polarizing plate 135, 136, 137, 169, 17 0,171 Emission-side polarizing plate 142,173 Projection lens 122,123,138,139,153,154 Dichroic mirror 124,140,155,158,159 Planar mirror 156,157 Relay lens 172 Color combining prism

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02F 1/1335 510 G02F 1/1335 510 G09F 9/00 360 G09F 9/00 360Z

Claims (19)

[Claims] 1. A prism array having a plurality of prisms each having a quadrangular cross section, wherein adjacent prisms in the prism array face each other via a slope, and the adjacent prisms have different refractive indexes. And a polarization separation film configured to separate natural light into two polarization components whose polarization directions are orthogonal to each other is sandwiched between inclined surfaces of the adjacent prisms. 2. The polarization separation device according to claim 1, wherein the prism array is composed of a plurality of prisms of two types having different refractive indexes. 3. The polarization separation device according to claim 1, wherein the angle between the incident side surface of the prism and the polarization separation film is 45 °. 4. The polarization separation device according to claim 1, wherein the angle between the exit side surface of the prism and the polarization separation film is 45 °. 5. The polarization separation device according to claim 1, wherein the incident side surfaces of each prism are aligned with one plane. 6. The polarization separation device according to claim 1, wherein the exit side surfaces of each prism are aligned on one plane. 7. A light source that emits natural light, a polarization separation device that receives light emitted from the light source and emits light of two polarization components whose polarization directions are orthogonal to each other in different directions, and the two polarization components. And a polarization direction correcting means for converting the light into a light having a uniform polarization direction, wherein the polarization separation device is the polarization separation device according to any one of claims 1 to 6, wherein the polarization direction correction means is provided. Rotates one polarization direction of the two polarization components by a predetermined angle including zero, and rotates the other polarization direction by 90 ° with respect to one polarization direction rotated by the predetermined angle including the zero. Thus, a polarized light illuminating device capable of irradiating an area to be irradiated with light close to linearly polarized light. 8. An incident-side lens array disposed near an entrance side or an exit side of a polarization separation device, and an exit-side lens array to which light emitted from the polarization separation device or the incidence-side lens array enters, The polarization direction correcting means is arranged near the entrance side or the exit side of the exit side lens array, and the entrance side lens array is a two-dimensional array of a plurality of entrance side lens elements, and the exit side lens array Is a two-dimensional array of a plurality of outgoing-side lens elements that form a pair with the incoming-side lens element, and two polarized light components corresponding to each of the incoming-side lens elements are coupled to each outgoing-side lens element. The output side lens element is configured to converge to different positions in the aperture of the element, and the emission side lens element is configured to form a real image of the aperture of the incident side lens element in an irradiated area. Item 7. The polarized illumination device according to item 7. 9. The incident-side lens array is disposed near the exit side of the polarization separation device, and includes an optical axis of a light source, an optical axis of polarization separation means, a normal direction of the entrance-side lens array, and an exit-side lens array. Are parallel to each other, and each of the incident-side lens elements has a center of its opening such that light of two polarization components travels in a substantially symmetrical direction with respect to the normal direction of the incident-side lens array. 9. is eccentric from the optical axis.
The polarized light illuminating device as described in the above. 10. The incident-side lens array is disposed near the incident side of the polarization splitting device, and includes an optical axis of a light source, an optical axis of the polarization splitting means, a normal direction of the incident-side lens array, and an emission-side lens array. Are parallel to each other, and each output side lens element is decentered from the optical axis at the center of its opening so that the two polarized light components travel in parallel with the normal direction of the output side lens array. 9. The polarized light illuminating device according to claim 8, wherein: 11. The polarized light illuminating apparatus according to claim 8, wherein the shape of the effective area of each lens element constituting the incident-side lens array is similar to the shape of the irradiated area. 12. The method according to claim 8, wherein a lateral width of an effective area of each lens element constituting the incident side lens array is substantially equal to a lateral width of an effective area on an emission side surface of a prism constituting a prism array of the polarization beam splitter. The polarized light illuminating device according to claim 1. 13. The vertical width of the effective area of each lens element forming the entrance-side lens array is substantially equal to the vertical width of the effective area of the exit side surface of the prism forming the prism array of the polarization beam splitter. The polarized light illuminating device according to any one of the above. 14. The polarized light illuminating device according to claim 8, wherein the incident side or the outgoing side of the incident side lens array is a plane, and the polarization splitting device and the incident side lens array are joined. . 15. A positive lens is arranged near the exit side of the exit side lens array so that the real images of the apertures of the respective entrance side lens elements substantially overlap each other in the irradiation area.
15. The polarized illumination device according to any one of items 1 to 14. 16. A polarized light illuminator for irradiating a region to be illuminated with light close to linearly polarized light, a light valve for receiving an emitted light from the polarized illuminator to form an optical image, and receiving light emitted from the light valve. And a projection lens for projecting the optical image, wherein the polarized light illuminating device is the polarized light illuminating device according to any one of claims 7 to 15. 17. The light valve forms an optical image as a change in polarization state, and the polarization illuminating device changes the polarization direction of the emitted light from the projection lens when the light valve has the maximum transmittance. 17. The projection display according to claim 16, wherein the output light is set to be substantially maximum. 18. A first step of processing a plurality of transparent flat plates of a first material and a plurality of transparent flat plates of a second material having a different refractive index from the first material into a predetermined thickness; A second step of attaching a polarization separation film to the transparent plate of the first material and the transparent plate of the second material, and the plurality of transparent plates of the first material and the plurality of transparent plates of the second material alternately; A third step of forming a first bonded body by adhering with a transparent adhesive so as to overlap the first bonded body; and cutting the first bonded body into a plurality of pieces at a predetermined angle with respect to a bonding surface and polishing the cut surface. And a fourth step of forming a plurality of second combined bodies by using the method. 19. In a third step, a transparent plate made of a first material and a transparent plate made of a second material are bonded to each other along the bonding surface by shifting by a thickness of the two types of transparent plates. A method for manufacturing the polarization separation device according to claim 18.