JPH1123842A - Polarization beam splitter, lighting optical system with the same polarization beam splitter, and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the polarization beam splitter which can efficiently separate an S and a P component over the entire visible light range. SOLUTION: The polarization beam splitter PBS is constituted by sandwiching a polarizing multi-layered film 3 between 1st and 2nd transparent base bodies 1 and 2 which have a refractive index nG. Then this polarizing multi-layered film 3 is composed of an alternate laminate film 31 formed by laminating a high-refractive-index layer 31H with a refractive index nH and a low-refractive-index layer 31L with a refractive index nL smaller than the refractive index nH alternately and satisfies the expression.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing beam splitter capable of efficiently separating an S component and a P component over the entire visible band, an illumination optical system using the polarizing beam splitter, and the polarizing beam splitter. And a projector using the same.

[0002]

2. Description of the Related Art A polarizing beam splitter divides a plane wave into two components by causing a plane wave to enter a polarizing multilayer film at a predetermined incident angle and reflecting an S component of the plane wave while transmitting a P component. There are known a prism type in which a multilayer film is sandwiched between a pair of prisms, and a plate type in which an incident angle of a plane wave with respect to a polarizing multilayer film provided on a flat substrate is a Brewster angle.

In order to utilize the above-described polarization splitting property, that is, the property of splitting a plane wave into an S component and a P component, a polarizing beam splitter is incorporated in the apparatus as a component and cooperates with the polarizing beam splitter. Various devices that exhibit excellent performance have been proposed. As one of the devices according to such a proposal, there is a liquid crystal projector, for example.

This liquid crystal projector is a device for projecting a large image on a screen. The liquid crystal projector forms an image similar in shape to the image to be projected on a liquid crystal panel, and an illumination optical system aligns the image with a predetermined polarization component. While forming light and irradiating the liquid crystal panel, the light emitted from the liquid crystal panel is guided onto a screen via a projection lens, thereby enlarging and projecting an image on the liquid crystal panel onto the screen. That is, in this liquid crystal projector, an illumination optical system is configured by a light source, a polarization beam splitter, and a half-wave plate, and the light emitted from the light source is incident on the polarization beam splitter at a predetermined incident angle to generate an S component. After being separated into P components, one of the components, for example, only the P component, is converted into an S component by passing through a half-wave plate to form light aligned with the S component, which is illuminated on the liquid crystal panel as illumination light. doing.

[0005]

By the way, in order to project a color image on a screen, a liquid crystal panel is prepared for each of the three primary colors (R color component, G color component and B color component). It is necessary to illuminate each liquid crystal panel with the corresponding illumination light. Therefore, it is necessary to use a white light source as a light source, and it is necessary to separate the light from the white light source into an S component and a P component by a polarizing beam splitter over the entire visible band (400 nm to 700 nm). Moreover, the separation efficiency, that is, the separation ratio, is closely related to the light intensity of the illumination light to the liquid crystal panel. When the separation ratio is low, the light intensity of the illumination light actually applied to the liquid crystal panel is low. Then, the image projected on the screen becomes dark. Therefore, the polarization beam splitter used in the color liquid crystal projector needs to have a polarization separation characteristic of being able to efficiently separate the S component and the P component over the entire visible band.

The incident angle θ of the light from the white light source to the polarizing multilayer film is usually set to 45 °.
Although the illumination optical system is designed so that the separation ratio becomes maximum, not only the light of the incident angle θ but also the light shifted by about ± 3 ° is incident on the polarizing multilayer film. Conventionally provided polarizing beam splitters have not sufficiently studied and considered such obliquely incident light. A similar problem had arisen.

The present invention has been made in view of the above problems, and provides a polarizing beam splitter that can efficiently separate an S component and a P component over the entire visible band. As a first object.

It is a second object of the present invention to provide an illumination optical system capable of illuminating an illuminated object with visible light having a uniform polarization direction.

It is a third object of the present invention to provide a projector capable of projecting a bright image on a screen.

[0010]

[Summary of the invention of claim 1 is a polarizing beam splitter made by sandwiching a polarizing multilayer film in the first and second transparent substrate having a refractive index n _G, achieve the first object to order, the polarizing multilayer film, the high refractive index layer with a refractive index n _H, is composed of alternating stacked film formed by alternately laminating low refractive index layer is lower than the refractive index n _H refractive index n _L And the following inequality

[0011]

(Equation 5)

It is configured to satisfy the following.

The invention of claim 2 is the center wavelength of the wavelength band to be branched with lambda _0, the lambda _0/4 layers of refractive index n _H and H, the lambda _0/4 layers of refractive index n _L is L, When m is a repetition period, the alternate laminated film is (first transparent substrate) | (H / 2 · L · H / 2) ^m | (second
(Transparent substrate), (first transparent substrate) | H / 2 · (H / 2 · L · H / 2) ^m
.H / 2 | (second transparent substrate), (first transparent substrate) | (L / 2.HL.L / 2) ^m | (second
(Transparent substrate), and (first transparent substrate) | L / 2 · (L / 2 · H · L / 2) ^m
· L / 2 | (second transparent substrate).

According to a third aspect of the present invention, the repetition period m is set to 5
It is set above.

[0015] The invention according to claim 4, a polarization beam splitter made by sandwiching a polarizing multilayer film in the first and second transparent substrate having a refractive index n _G, in order to achieve the first object, the polarization multilayer film, and the high refractive index layer with a refractive index n _H, the light in a wavelength band about a central wavelength lambda ₀ by alternately laminating a low refractive index layer is lower than the refractive index n _H refractive index n _L A first alternately laminated film capable of branching, the high refractive index layer and the low refractive index layer alternately laminated to branch light in a wavelength band around a center wavelength λ ₁ (> λ ₀ ). 2 alternately laminated films, and the following inequality

[0016]

(Equation 6)

It is configured to satisfy the following.

[0018] When the invention of claim 5, the lambda _0/4 layers of refractive index n _H and H, the lambda _0/4 layers of refractive index n _L is L, which is the period repeatedly m, n, the said alternating The laminated film is (first transparent substrate) | [H / 2 · (H / 2 · L · H / 2)
^m ] · A [(H / 2 · L · H / 2) ⁿ · H / 2] | (second
(Transparent substrate), (First transparent substrate) | (H / 2 · L · H / 2) ^mA · (H
/ 2 · L · H / 2) ⁿ | (second transparent base), (first transparent base) | [L / 2 · (L / 2 · H · L / 2)
^m ] · A [(L / 2 · H · L / 2) ⁿ · L / 2] | (second
(Transparent substrate), and (first transparent substrate) | (L / 2 · HL / 2) ^mA (L
/ 2 · HL / 2) ⁿ | (second transparent substrate), where 1.0 <A ≦ 1.38.

The invention according to claim 6 is characterized in that the repetition period m, n
Is set to 5 or more.

A seventh aspect of the present invention is a polarizing beam splitter comprising a polarizing multilayer film sandwiched between first and second transparent substrates having a refractive index of n _G , wherein the polarizing multilayer film has a refractive index of n _H
Alternately stackable by alternately stacking a high refractive index layer having a refractive index n _L lower than the refractive index n _H and branching light in a wavelength band around a center wavelength λ _0. A film, and the high refractive index layer and the low refractive index layer are alternately laminated to form a center wavelength λ ₁
( ₂ ) capable of splitting light in a wavelength band centered on (> λ ₀ )
An alternately laminated film, and a third alternately laminated film capable of branching light in a wavelength band centered on a center wavelength λ ₂ (> λ ₁ ) by alternately laminating the high refractive index layer and the low refractive index layer; Layered,
Moreover, the following inequality

[0021]

(Equation 7)

It is configured to satisfy the following.

The invention of claim 8, the lambda _0/4 layers of refractive index n _H and H, the lambda _0/4 layers of refractive index n _L and L, m, n, p
Is the repetition period, the alternate laminated film is (first transparent substrate) | [H / 2 · (H / 2 · L · H / 2)
^m ] · A [(H / 2 · L · H / 2) ⁿ · B [(H / 2 · L
· H / 2) ^p · H / 2] | (second transparent substrate) or (first transparent substrate) | (H / 2 · L · H / 2) ^m · A (H
/ LH / 2) ^nB (H / 2LH / 2) ^p |
(2nd transparent substrate), (1st transparent substrate) | [L / 2 · (L / 2 · H · L / 2)
^m ] · A [(L / 2 · H · L / 2) ⁿ · B [(L / 2 · H
(L / 2) ^p · L / 2] | (second transparent substrate) and (first transparent substrate) | (L / 2 · HL / 2) ^mA (L
/ 2 · H · L / 2) ⁿ · B (L / 2 · H · L / 2) ^p |
(Second transparent substrate), provided that it has a configuration represented by any one of 1.0 <A ≦ 1.22 and 1.22 <B <1.49.

According to a ninth aspect of the present invention, the repetition period m,
n and p are each set to 5 or more.

The invention of claim 10 is based on the following equation:

[0026]

(Equation 8)

Is further satisfied.

An eleventh aspect of the present invention is an illumination optical system for generating visible light having a uniform polarization direction, and in order to achieve the second object, the illumination optical system according to any one of the first to tenth aspects. A polarizing beam splitter, a light source that generates visible light having a visible band, and impinges the visible light on the polarizing beam splitter, and changes the polarization direction of one of the two linearly polarized lights separated by the polarizing beam splitter to the other. And a conversion unit for converting the direction.

According to a twelfth aspect of the present invention, the incident angle of the visible light on the polarizing beam splitter is 45 °.

According to a thirteenth aspect of the present invention, there is provided an illumination optical system for generating visible light having a uniform polarization direction, and after separating the visible light from the illumination optical system into a plurality of primary color lights, the respective primary color lights correspond to each other. A color separation optical system for irradiating each of the panels, and a projection for guiding color component lights emitted from the plurality of panels onto a screen while aligning optical axes thereof, and projecting an image formed on the panel on the screen. A projector including an optical system, in order to achieve the third object,
The illumination optical system, the polarization beam splitter according to any one of claims 1 to 10, a light source that generates visible light having a visible band, and enters the visible light into the polarization beam splitter; And a converter for converting one polarization direction of the two linearly polarized lights separated by the beam splitter into the other polarization direction.

According to a fourteenth aspect of the present invention, the incident angle of the visible light on the polarizing beam splitter is 45 °.

According to the present invention, the polarizing multilayer film is composed of a single alternately laminated film, has a so-called double structure in which two alternately laminated films are superposed, or is formed by superposing three alternately laminated films. In addition, it is configured so as to satisfy a predetermined inequality according to whether it is a so-called triple structure. By satisfying the corresponding inequalities in this manner, even if oblique incident light is included in addition to light incident at a predetermined incident angle, the efficiency can be reduced to the S component and the P component over the entire visible band. Can be well separated. The details will be described later.

According to the third, sixth and ninth aspects of the present invention,
The repetition period of the high refractive index layer and the low refractive index layer is set to 5 or more, and the S component and the P component are efficiently separated by the polarizing beam splitter.

According to the tenth aspect of the present invention, Expression 8 is satisfied, and the separation efficiency is maximized when the angle of incidence on the polarizing beam splitter is 45 °.

In the illumination optical system according to the eleventh aspect, the polarizing beam splitter according to any one of the first to tenth aspects efficiently separates visible light, so that two straight lines separated by the polarizing beam splitter are used. The polarized light can be efficiently used for illuminating the illuminated object.

Further, in the projector according to the thirteenth aspect,
Since the polarizing beam splitter according to any one of claims 1 to 10 efficiently separates visible light, the panel can be efficiently irradiated with two linearly polarized lights separated by the polarizing beam splitter. The amount of light emitted from the panel increases, and the projected image on the screen becomes bright.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION

A. First Embodiment FIG. 1 shows a first embodiment of a polarizing beam splitter according to the present invention.
It is sectional drawing which shows embodiment. The polarization beam splitter PBS, as shown in the figure, is made by sandwiching a polarizing multilayer film 3 in the first and second transparent substrates 1 and 2 of the refractive index n _G. The polarizing multilayer film 3 has a refractive index n _H
High refractive index layer 31H and refractive index n _L lower than refractive index n _H
And a low-refractive-index layer 31L are alternately laminated, and the following inequality

[0038]

(Equation 9)

Is satisfied. Here, the meaning of Equation 9 will be described in detail.

The alternate laminated film 3 configured as shown in FIG.
Assuming that the incident angle of light to 1 is θ, as conventionally known,

[0041]

(Equation 10)

When the following relational expression is satisfied, the S component (hereinafter referred to as “S-polarized light”) and the P component (hereinafter referred to as “P-polarized light”)
And can be separated efficiently. The center wavelength of the wavelength band (hereinafter, referred to as “separable wavelength band”) that can be efficiently separated by the alternating laminated film 31 is λ _0, and the upper and lower wavelengths are (1 + Δg), respectively.
Assuming that λ ₀ and (1−Δg) · λ ₀ , Δg is as follows.

[0043]

[Equation 11]

That is, as shown by the solid line in FIG. 2, the transmittance T _S (θ) of the S-polarized light transmitted through the alternating laminated film 31 is (1 + Δg) · λ ₀ to (1−Δg) centered on the center wavelength λ _0. )
-It is efficiently separated in the wavelength band B ₀ of λ ₀ . In addition,
The solid line T _P (θ) in the figure indicates the transmittance TP of P-polarized light.

On the other hand, when light is incident on the alternately laminated film 31 having the above-described polarization splitting characteristic at an incident angle (θ + δ), as shown by a dashed line in FIG.
_{+ δ} shifts to the short wavelength side,

[0046]

(Equation 12)

In addition, the upper limit wavelength (1 + Δg _{+ δ} ) · λ _{+ δ} of the wavelength band B _{+ δ that} can be efficiently separated is

[0048]

(Equation 13)

Is as follows.

On the other hand, when the light is incident on the alternately laminated film 31 having the above-described polarization splitting characteristic at an incident angle (θ−δ),
As shown by the broken line in the figure, the center wavelength λ- _δ shifts to the longer wavelength side,

[0051]

[Equation 14]

The lower limit wavelength (1 + Δg− _δ ) · λ− _δ of the wavelength band B− _{δ that} can be efficiently separated is

[0053]

(Equation 15)

Is as follows. Therefore, even if light is incident on the polarizing multilayer film 3 within an angle range of ± δ around the incident angle θ, a wavelength at which incident light can be efficiently separated into S-polarized light and P-polarized light at all incident angles. The upper limit wavelength WL _max of the band BB is

[0055]

(Equation 16)

On the other hand, the lower limit wavelength WL _min is

[0057]

[Equation 17]

Is as follows.

Here, in the projector, the incident angle θ of visible light (400 nm to 700 nm) on the polarizing multilayer film is 45 °.
The angle ゜ is generally set so as to maximize the separation ratio, and it is necessary to consider oblique incidence shifted by about ± 3 °. Therefore, in order to efficiently perform polarization separation under the conditions of an upper limit wavelength WL _max = 700 nm, a lower limit wavelength WL _min = 400 nm, an incident angle θ = 45 °, and a shift angle amount δ = 3 °,

[0060]

(Equation 18)

It is necessary to satisfy the following conditions.

Considering the refractive index of the thin film material usable in the visible band, the relationship between Δg and Δg _{+ δ} can be approximated as Δg _{+ 3} = Δg / 0.9, and the relationship between Δg and Δg− _δ The relationship can be approximated as Δg ₋₃ = 0.9 · Δg. Therefore, by substituting these approximations into Equation 18,

[0063]

[Equation 19]

By satisfying Expression 19, a polarizing beam splitter capable of efficiently separating S-polarized light and P-polarized light over the entire visible band (400 nm to 700 nm) can be obtained. Thus, solving equation 19 yields the inequality shown in equation 9. That is, by constructing the polarizing beam splitter so as to satisfy the expression 9, that is, correspond to the hatched band in FIG. 3, in addition to the light incident at the incident angle of 45 °, ± 3 ° of the incident angle of 45 ° is obtained. Even if oblique incidence is included, the visible band (400 nm to 700 n
m) S-polarized light and P-polarized light can be efficiently separated over the entirety.

Further, by substituting the incident angle θ = 45 ° into Equation 10 and rearranging the equation,

[0066]

(Equation 20)

By satisfying the expression 20, the separation efficiency is maximized at an incident angle of 45 °. For example, the refractive index n along each of the curves l ₁ , l ₂ , l ₃ and l ₄ in FIG. _G, in the setting the n _H and n _L, it is possible separation efficiency at the incident angle θ is maximum, is separated into a more efficient S-polarized light and P-polarized light.

B. Second Embodiment FIG. 4 shows a second embodiment of the polarizing beam splitter according to the present invention.
It is sectional drawing which shows embodiment. The polarization beam splitter PBS, as shown in the figure, is made by sandwiching a polarizing multilayer film 3 in the first and second transparent substrates 1 and 2 of the refractive index n _G. In the polarization beam splitter PBS according to the second embodiment, the polarization multilayer film 3 is composed of two alternately laminated films 31 and 32. Each of the alternately laminated films 31 and 32 has the same configuration as that of the first embodiment. That is, alternate stacked film 31 includes a high-refractive-index layer 31H having a refractive index n _H, with a low refractive index layer 31L is formed by laminating alternately a lower than the refractive index n _H refractive index n _L, alternately laminated film 32 high refractive index layer with a refractive index n _H 32
H and a low refractive index layer 32L having a low refractive index n _L are alternately laminated.

Further, the polarizing multilayer film 3 having the above-described structure is used.
Is the inequality

[0070]

(Equation 21)

Satisfying the visible band (400 nm to 400 nm).
(700 nm), and a polarizing beam splitter capable of efficiently separating into S-polarized light and P-polarized light can be obtained. Here, the meaning of Equation 21 will be described in detail.

In the so-called double-layered polarizing multilayer film 3 in which the two alternately laminated films 31 and 32 having the same structure are superposed as described above, the separable wavelength band of each of the alternately laminated films 31 and 32 is shifted. The separable wavelength band of the polarizing multilayer film 3 can be expanded. That is, the alternate laminated film 3
The upper limit and lower limit wavelengths of one separable wavelength band centered on the wavelength λ ₀ are (1 + Δg) · λ ₀ , (1−Δ
g) · λ ₀ , and the upper limit and lower limit wavelengths of the alternately laminated film 32 are K · (1 + Δg) · λ ₀ and K · (1−Δ, respectively, centered on the wavelength K · λ _0.
g) · λ ₀ , as shown in FIG. 5A, the upper limit wavelength (1 + Δg) · λ of the separable wavelength band of the alternately laminated film 31.
₀ , the lower limit wavelength K of the separable wavelength band of the alternate laminated film 32
· (1-Δg) · λ ₀ is matched, that is,

[0073]

(Equation 22)

By satisfying the above condition, the polarizing multilayer film 3
Can be separated.

However, the separation efficiency at the wavelength of the joint tends to be low. To prevent this, the number of the high refractive index layers 31H and the low refractive index layers 31L constituting the polarizing multilayer film 3 is reduced. Must be set large. Therefore, in order to prevent a decrease in separation efficiency with an appropriate number of layers, the value of K should be adjusted.

[0076]

(Equation 23)

It is desirable to partially overlap the separable wavelength band of the alternately laminated film 31 with the separable wavelength band of the alternately laminated film 32 as shown in FIG.

Here, similarly to the case of the first embodiment, under various conditions in the projector, the upper limit wavelength WL _max = 700 nm, the lower limit wavelength WL _min = 400 nm, the incident angle θ = 45 °, and the shift angle amount δ = 3 °. For efficient polarization separation at,

[0079]

(Equation 24)

It is necessary to satisfy the following conditions. Therefore,
Solving Equation 24 yields the inequality shown in Equation 21. That is, by configuring the polarizing beam splitter so as to satisfy Expression 21, that is, correspond to the shaded region in FIG. 6, in addition to the light incident at an incident angle of 45 °, ±
Even if 3 ° oblique incidence is included, the visible band (40
0 nm to 700 nm), and S-polarized light and P
It can be efficiently separated from polarized light.

By satisfying the expression (20), the incident angle 45
分離, the separation efficiency is maximized. For example, each curve l ₁ ,
By setting the refractive indices n _G , n _H and n _L along l ₂ , l ₃ and l ₄ , the separation efficiency at the incident angle θ is maximized, and the light is more efficiently separated into S-polarized light and P-polarized light. can do.

C. Third Embodiment FIG. 7 shows a third embodiment of the polarizing beam splitter according to the present invention.
It is sectional drawing which shows embodiment. The polarization beam splitter PBS, as shown in the drawing, a stack of three alternately-layered films 31 to 33 of the same configuration in the first and second transparent substrates 1 and 2 of the refractive index n _G, the so-called three-layer structure The polarizing multilayer film 3 is sandwiched therebetween. Note that each of the alternating laminated films 31 to 33 has a refractive index n similar to that of the first embodiment.
_H high refractive index layers 31H, 32H, 33H and low refractive index layers 31L, 32L, 33 having a refractive index n _L lower than the refractive index n _H.
And L are alternately laminated.

Further, the polarizing multilayer film 3 having the above-described structure is used.
Is the inequality

[0084]

(Equation 25)

Satisfying the visible band (400 nm to 400 nm).
(700 nm), and a polarizing beam splitter capable of efficiently separating into S-polarized light and P-polarized light can be obtained. Here, the meaning of Expression 25 will be described in detail.

As described above, in the polarizing multilayer film 3 having the triple structure, similarly to the case of the double structure (the second embodiment),
By shifting the separable wavelength band of each of the alternating laminated films 31 to 33, the separable wavelength band of the polarizing multilayer film 3 can be widened. Alternating laminated film 31 at lower wavelength side of wavelength band
And the upper limit wavelength side is desirably partially overlapped with the separable wavelength band of the alternately laminated film 33.

Therefore, similarly to the case of the first embodiment, under various conditions in the projector, the upper limit wavelength WL _max = 700 nm, the lower limit wavelength WL _min = 400 nm, the incident angle θ = 45 °, the shift angle amount δ = 3 °, For efficient polarization separation at

[0088]

(Equation 26)

It is necessary to satisfy the following conditions. Therefore,
Solving Equation 26 yields the inequality shown in Equation 25. That is, by configuring the polarizing beam splitter so as to satisfy the expression 25, that is, correspond to the shaded region in FIG.
Even if 3 ° oblique incidence is included, the visible band (40
0 nm to 700 nm), and S-polarized light and P
It can be efficiently separated from polarized light.

By satisfying the expression (20), the incident angle 45
分離 maximizes the separation efficiency. For example, each curve l ₁ ,
By setting the refractive indices n _G , n _H and n _L along l ₂ , l ₃ and l ₄ , the separation efficiency at the incident angle θ is maximized, and the light is more efficiently separated into S-polarized light and P-polarized light. can do.

As described above, by constructing the polarizing beam splitter PBS so as to satisfy any one of Expressions 9, 22, and 25 according to the structure of the polarizing multilayer film 3, the visible band (400 nm to 400 nm) can be obtained. 700 nm), and can be efficiently separated into S-polarized light and P-polarized light.

Further, by configuring the polarizing beam splitter PBS so as to further satisfy Expression 20, the incident angle 4
The separation efficiency can be set to the maximum at 5 °, which is suitable for the projector.

The specific structure and separation characteristics of the polarizing multilayer film will be described in detail in the following examples.

D. FIG. 9 is a diagram illustrating a configuration of a liquid crystal projector to which the polarization beam splitter according to the present invention is applied. This liquid crystal projector includes an illumination optical system 100 for generating visible light having a uniform polarization direction, and three liquid crystal panels 23 to 25.
After the visible light from the illumination optical system 100 is color-separated into a plurality of primary color lights, each primary color light is
The color separation optical system 200 for irradiating the liquid crystal panel 25 with each other and the color component light emitted from each of the liquid crystal panels 23 to 25 are guided on a screen while aligning the optical axes, and formed on the liquid crystal panels 23 to 25 on the screen. And a projection optical system 300 that projects the projected image. Hereinafter, the configuration of each unit will be sequentially described.

The illumination optical system 100 is configured so that visible light in a predetermined visible band is incident on the polarizing beam splitter PBS by a light source 101, a parabolic mirror 102 and an IR-UV cut filter 103. That is, the light source 101 is a metal halide lamp that emits randomly polarized white light. The parabolic mirror 102 has a reflecting surface 102a whose section is axisymmetrically formed on a part of the surface including the poles of the paraboloid of revolution, and has a focal point (the light source 101 is set at the position of the focal point. ) Is a mirror that reflects the light radiated from the opening 102b to the outside of the opening 102b (to the right in FIG. 9). The IR-UV cut filter 103 has an opening 10
2b is a filter arranged near the light source 101b.
From the direct light from
Light in a wavelength range that is unnecessary for the light of the primary colors is removed to form desired visible light.

The visible light thus formed enters the first lens array 104 constituting the optical integrator. The first lens array 104 has a plurality of first lenses 104a two-dimensionally arranged, and divides the visible light into a plurality of light fluxes and emits the light toward the polarization beam splitter PBS.

The polarization beam splitter PBS is formed, for example, in the same manner as in the first embodiment. That is, the polarizing beam splitter PBS includes a triangular prism-shaped transparent glass (first transparent substrate) 1 and a glass plate (second transparent substrate) 2.
And the polarizing multilayer film 3 is formed between them. The polarizing multilayer film 3 and the back surface 2a of the glass plate 2 are arranged so as to form an angle of 45 ° with the optical axis of the first lens array 104. When each of the split light beams enters,
A first linearly polarized light beam (S-polarized light) 6 and a second linearly polarized light beam (P-polarized light) 7 whose polarization directions are orthogonal to each other
And separated. That is, the first linearly polarized light component of the visible light incident from the first lens array 4 is reflected by the polarizing multilayer film 3 at a right angle to the incident angle of 45 degrees, and the luminous flux (S
(Polarized light) 6. On the other hand, the back surface 2 of the glass plate 2 provided at a distance of 2 b from the polarizing multilayer film 3.
a functions as a total reflection surface, and a second linearly polarized light component orthogonal to the first linearly polarized light component of the visible light incident from the first lens array 4 is incident on the back surface 2a at 45 degrees. The light is reflected at right angles to the angles and emitted as a light beam (P-polarized light) 7. Note that the size of the thickness 2b is set based on the pitch at which the light flux 6 and the light flux 7 are emitted ( ^21/2 times the thickness 2b) and the pitch of the second lens 10a.

The second lens array 8 constituting the optical integrator is arranged two-dimensionally in the vicinity where the plurality of light beams 6 and 7 separated by the polarizing beam splitter PBS are converged. Is a lens array having the same number of second lenses 10a as the number of light fluxes 7 of the first embodiment. That is, the second lens array 10 has twice as many lenses as the number of the plurality of first lenses 104a included in the first lens array 104, and each two adjacent lenses in the vertical direction in FIG. The second lens 10a is a first lens 104
a. A part of the exit surface of the second lens array 10 from which the light beam 7 is emitted is provided for converting the second linearly polarized light of the light beam 7 into the same polarization direction as the first linearly polarized light of the light beam 6. A half-wave plate (converter) 10b is attached. Therefore, the second lens array 1
In the visible light emitted from the zero and half-wave plate 10b,
The polarization direction is aligned with the first linear polarization direction.

In the illumination optical system 100 configured as described above, since the polarizing beam splitter PBS according to the present invention is used, the visible light from the lens array 104 is efficiently converted into two linearly polarized lights (S-polarized light and P-polarized light). ), Can be efficiently used to illuminate the liquid crystal panel 23 as an object to be illuminated, and the object to be illuminated can be brightly illuminated.

The liquid crystal panel 23 is a transmissive liquid crystal panel, and forms an optical image of B of RGB. The liquid crystal panel 24 is a transmissive liquid crystal panel, and forms an optical image of G of RGB. The liquid crystal panel 25 is a transmissive liquid crystal panel, and forms an optical image of R of RGB.

A color separation system 200 for illuminating each of the three liquid crystal panels 23 to 25 with light of the corresponding primary color and separating each of the three primary colors is composed of a dichroic filter 11 and a dichroic filter 12. . The dichroic filter 11 has a cutoff value of a wavelength of 510 nm, reflects a light beam in the B wavelength band, and transmits a light beam in the R and G wavelength bands. The total reflection mirror 13 directs the separated light beam in the B wavelength band toward the liquid crystal panel 23. The field lens 14 converts the luminous flux of the B wavelength band reflected by the total reflection mirror 13 into a liquid crystal panel 23.
It is for irradiating to. The dichroic filter 12 has a cutoff value of a wavelength of 580 nm, and reflects the G wavelength band light flux and transmits the R wavelength band light flux among the R and G wavelength band light fluxes transmitted through the dichroic filter 11. Let it. The field lens 15 is for irradiating the liquid crystal panel 24 with the light flux in the G wavelength band separated by the dichroic filter 12. Lens 1
9, 20 and the total reflection mirrors 17 and 18 constitute a relay optical system for guiding the light flux in the R wavelength band transmitted through the dichroic filter 12 to the liquid crystal panel 25 while maintaining its illuminance. , The luminous flux of the R wavelength band guided by the relay optical system is
It is for irradiating to.

The dichroic prism 21 is formed by joining four right-angle prisms so as to form a cube or a rectangular parallelepiped, and a dichroic mirror portion is formed on the joint surface. The dichroic prism 21 is formed by three liquid crystal panels 23 to 25. The optical images of the respective RGB colors are combined.

The projection lens 22 is a projection optical system 300 for enlarging and projecting the color optical image synthesized by the dichroic prism 21 on a screen.

As described above, in this liquid crystal projector, the polarizing beam splitter PB
Since S is incorporated, the liquid crystal panel 23 can be brightly illuminated. As a result, the amount of light emitted from the liquid crystal panel 23 can be increased, and the projected image on the screen can be brightened.

In the above description, an example in which the polarizing beam splitter according to the present invention is applied to a liquid crystal projector has been described. However, the application of the polarizing beam splitter is not limited to a liquid crystal projector, but is applied to a normal projector. Is also applicable, and the same effect as above can be obtained.

Further, the form of the illumination optical system is not limited to the one shown in FIG. 9; for example, as shown in FIGS.
May be configured to separate the polarized light by each of the polarizing multilayer films 3. In any case, since the polarizing beam splitter PBS according to the present invention is used, the visible light from the light source 101 can be efficiently transmitted. Two linearly polarized lights (S polarized light and P
(Polarized light), and can be efficiently used to illuminate the illuminated object, and the illuminated object can be brightly illuminated.

Further, in the above description, the illumination optical system is configured using the polarization beam splitter according to the present invention, but the application of the polarization beam splitter is not limited to the illumination optical system. For example, Japanese Patent Publication 5-73
In the projection type stereoscopic television receiver described in JP-A-116, the P-polarized light and the S-polarized light are superimposed on the same optical axis by a polarizing beam splitter and projected on a screen. Such a polarization beam splitter can be applied. Thus, by applying the polarization beam splitter according to the present invention, P-polarized light and S-polarized light can be efficiently guided on the screen, and a bright image can be formed on the screen.

[0108]

Next, specific examples of the polarizing beam splitter according to the first to third embodiments will be described.

E. Polarizing Beam Splitter According to First Embodiment <First Example> After precisely cleaning the surface of a first transparent substrate having a refractive index n _G of 1.80, the surface is removed from the surface using a thin film forming method such as a vacuum evaporation method. The first composed of the materials shown in Table 1
The polarizing multilayer film was formed by sequentially forming the layer to the eleventh layer. Further, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.80) is attached to obtain the polarizing beam splitter according to the first embodiment.

[0110]

[Table 1]

In the table (and the table described later), “QWOT” means 4nd / λ ₀ . Accordingly, in the polarizing multilayer film of the polarizing beam splitter configured as shown in Table 1, if the λ0 / 4 layer having a high refractive index n _H is _{H and} the λ0 / 4 layer having a low refractive index n _L is L, (1 transparent substrate) | (H / 2 · L · H / 2) ⁵ | (second
Transparent substrate), and the film structure can be expressed.

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter constructed as described above at incident angles of 45 ° and 45 ° ± 3 °.
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 12 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at the incident angle of 45 °, the visible band (400 nm to 70 nm) is obtained.
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

In this embodiment, the repetition period of the high refractive index layer and the low refractive index layer is set to 5, but the repetition period is not limited to this. However, when the transmittance of the S-polarized light with respect to the incident angle of 45 ° was calculated for the polarizing beam splitters having different repetition periods m, the graph shown in FIG. 13 was obtained. As can be seen from the drawing, as the repetition period m increases, the polarization separation characteristics improve, and it is desirable to set the repetition period m to 5 or more. This tendency is the same in the embodiments described later.

Further, the structure in which the high refractive index layer and the low refractive index layer are exchanged, that is, (first transparent substrate) | (L / 2 · HL / 2) ^m | (second
When a polarizing beam splitter is formed with a structure called “transparent substrate” or another structure, for example, (first transparent substrate) | H / 2 · (H / 2 · L · H / 2) ^m
· H / 2 | (second transparent substrate) or (first transparent substrate) | L / 2 · (L / 2 · HL / 2) ^m
The same effect was obtained even if the polarizing beam splitter was configured with a structure such as L / 2 | (second transparent substrate).

F. Polarizing Beam Splitter According to Second Embodiment <Second Example> After precisely cleaning the surface of a first transparent substrate having a refractive index n _G of 1.80, the surface is removed from the surface using a thin film forming method such as a vacuum evaporation method. The first composed of the materials shown in Table 2
The polarizing multilayer film was formed by sequentially forming the layer to the 26th layer. Further, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.80) is adhered to obtain the polarizing beam splitter according to the second embodiment.

[0117]

[Table 2]

[0118] In the polarizing multilayer film constructed polarization beam splitter as the table, the lambda _0/4 layers of high refractive index n _H and H, when the lambda _0/4 layers of low refractive index n _L and L , (first transparent substrate) | (H / 2 · L · H / 2) 6 · 1.3
6 (H / 2 · L · H / 2) ⁶ | (second transparent substrate).

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter configured as described above at incident angles of 45 ° and 45 ° ± 3 °.
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 14 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at the incident angle of 45 °, the visible band (400 nm to 70 °) is obtained.
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

<Third Embodiment> After the surface of the first transparent substrate having a refractive index n _G of 1.62 is precisely cleaned, the material shown in Table 3 is formed from the surface using a thin film forming method such as a vacuum evaporation method. A polarizing multilayer film was formed by sequentially forming the first to 26th layers that were configured. Furthermore, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.62) is attached to obtain the polarizing beam splitter according to the second embodiment.

[0122]

[Table 3]

[0123] In the polarizing multilayer film constructed polarization beam splitter as the table, the lambda _0/4 layers of high refractive index nH H
And then, when the lambda _0/4 layers of low refractive index n _L and L, (first transparent substrate) | (H / 2 · L · H / 2) 6 · 1.3
6 (H / 2 · L · H / 2) ⁶ | (second transparent substrate).

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter constructed as described above at incident angles of 45 ° and 45 ° ± 3 °.
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 15 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at the incident angle of 45 °, the visible band (400 nm to 70
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

<Fourth Embodiment> After the surface of the first transparent substrate having a refractive index n _G of 1.80 is precisely cleaned, the surface is coated with a material shown in Table 4 using a thin film forming method such as a vacuum evaporation method. A polarizing multilayer film was formed by sequentially forming the first to 26th layers that were configured. Further, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.80) is adhered to obtain the polarizing beam splitter according to the second embodiment.

[0127]

[Table 4]

[0128] In the polarizing multilayer film constructed polarization beam splitter as the table, the lambda _0/4 layers of high refractive index n _H and H, when the lambda _0/4 layers of low refractive index n _L and L , (First transparent substrate) | [H / 2 · (H / 2 · L · H / 2)
⁶ ] · 1.36 [(H / 2 · L · H / 2) ⁶ · H / 2] |
(Second transparent substrate), and the film structure can be expressed.

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter constructed as described above at incident angles of 45 ° and 45 ° ± 3 °.
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 16 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at the incident angle of 45 °, the visible band (400 nm to 70 °) is obtained.
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

<Fifth Embodiment> After the surface of the first transparent substrate having a refractive index n _G of 1.62 is precisely washed, the surface shown in FIG. A polarizing multilayer film was formed by sequentially forming the first to 26th layers that were configured. Furthermore, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.62) is attached to obtain the polarizing beam splitter according to the second embodiment.

[0132]

[Table 5]

[0133] In the polarizing multilayer film constructed polarization beam splitter as the table, the lambda _0/4 layers of high refractive index n _H and H, when the lambda _0/4 layers of low refractive index n _L and L , (First transparent substrate) | [H / 2 · (H / 2 · L · H / 2)
⁶ ] · 1.36 [(H / 2 · L · H / 2) ⁶ · H / 2] |
(Second transparent substrate), and the film structure can be expressed.

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter constructed as described above at incident angles of 45 ° and 45 ° ± 3 °.
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 17 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at the incident angle of 45 °, the visible band (400 nm to 70 °) is obtained.
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

Incidentally, the structure in which the high refractive index layer and the low refractive index layer are exchanged, that is, (first transparent substrate) | [L / 2 · (L / 2 · H · L / 2)
^m ] · A [(L / 2 · H · L / 2) ⁿ · L / 2] | (second
(Transparent substrate) or (First transparent substrate) | (L / 2 · HL / 2) ^mA (L
/ 2 · HL / 2) ⁿ | (second transparent substrate), etc., the same effect was obtained even if the polarizing beam splitter was configured.

Further, the value of A is not limited to the value “1.36” in the second to fifth embodiments, and as a result of various experiments, A was determined in the range of 1 <A ≦ 1.38. By setting, the same effect as in the above embodiment can be obtained.

G. Polarizing beam splitter according to third embodiment <Sixth embodiment> After precisely cleaning the surface of a first transparent substrate having a refractive index n _G of 1.52, the surface is removed from the surface using a thin film forming method such as a vacuum evaporation method. The first composed of the materials shown in Table 6
The polarizing multilayer film was formed by sequentially forming the layers to the 57th layer. Further, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.52) is attached to obtain the polarizing beam splitter according to the third embodiment.

[0139]

[Table 6]

[0140] In the polarizing multilayer film constructed polarization beam splitter as the table, the lambda _0/4 layers of high refractive index n _H and H, when the lambda _0/4 layers of low refractive index n _L and L , (first transparent substrate) | (H / 2 · L · H / 2) 9 · 1.2
2 (H / 2 · L · H / 2) 9 · 1.48 (H / 2 · L ·
H / 2) ⁹ | (second transparent substrate).

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter constructed as described above at incident angles of 45 ° and 45 ° ± 3 °.
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 18 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at the incident angle of 45 °, the visible band (400 nm to 70 nm) is obtained.
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

<Seventh Embodiment> After the surface of a first transparent substrate having a refractive index n _G of 1.80 is precisely cleaned, the surface is coated with a material shown in Table 6 using a thin film forming method such as a vacuum evaporation method. A polarizing multilayer film was formed by sequentially forming the first layer to the 57th layer that were configured. Further, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.80) is attached to obtain a polarizing beam splitter according to the third embodiment.

[0144]

[Table 7]

[0145] In the polarizing multilayer film constructed polarization beam splitter as the table, the lambda _0/4 layers of high refractive index n _H and H, when the lambda _0/4 layers of low refractive index n _L and L , (first transparent substrate) | (H / 2 · L · H / 2) 9 · 1.2
2 (H / 2 · L · H / 2) 9 · 1.48 (H / 2 · L ·
H / 2) ⁹ | (second transparent substrate).

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter constructed as described above at incident angles of 45 ° and 45 ° ± 3 °.
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 19 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at the incident angle of 45 °, the visible band (400 nm to 70 °) is obtained.
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

<Eighth Embodiment> After the surface of the first transparent substrate having a refractive index n _G of 1.52 is precisely cleaned, the material shown in Table 8 is formed from the surface using a thin film forming method such as a vacuum evaporation method. A polarizing multilayer film was formed by sequentially forming the first layer to the 57th layer that were configured. Further, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.52) is attached to obtain the polarizing beam splitter according to the third embodiment.

[0149]

[Table 8]

[0150] In the polarizing multilayer film constructed polarization beam splitter as the table, the lambda _0/4 layers of high refractive index n _H and H, when the lambda _0/4 layers of low refractive index n _L and L , (First transparent substrate) | [H / 2 · (H / 2 · L · H / 2)
^9] - 1.22 [(H / 2 · L · H / 2) 9 · 1.48
[(H / 2 · L · H / 2) ⁹ · H / 2] | (second transparent substrate).

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter constructed as described above at incident angles of 45 ° and 45 ° ± 3 °.
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 20 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at the incident angle of 45 °, the visible band (400 nm to 70
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

<Ninth Embodiment> The surface of the first transparent substrate having a refractive index n _G of 1.80 was precisely washed, and then the thin film was formed with a material shown in Table 9 using a thin film forming method such as a vacuum evaporation method. A polarizing multilayer film was formed by sequentially forming the first layer to the 57th layer that were configured. Further, after forming an adhesive layer on the polarizing multilayer film, a second transparent substrate (refractive index n _G = 1.80) is attached to obtain a polarizing beam splitter according to the third embodiment.

[0154]

[Table 9]

[0155] In the polarizing multilayer film constructed polarization beam splitter as the table, the lambda _0/4 layers of high refractive index n _H and H, when the lambda _0/4 layers of low refractive index n _L and L , (First transparent substrate) | [H / 2 · (H / 2 · L · H / 2)
^9] - 1.22 [(H / 2 · L · H / 2) 9 · 1.48
[(H / 2 · L · H / 2) ⁹ · H / 2] | (second transparent substrate).

Next, light in the visible band is made incident on the polarizing multilayer film of the polarizing beam splitter configured as described above at incident angles of 45 ° and 45 ° ± 3 °, and each of the incident angles 42
S-polarized light transmittance T _S (θ−45 °, 48 °)
δ), T _s (θ), and T _s (θ-δ) are calculated, and the transmittances _{P P} (θ-δ) and _TP ( _P ) of the P-polarized light at the respective incident angles of 42 °, 45 °, and 48 ° are calculated. θ), T _P (θ-δ)
Was calculated, a graph shown in FIG. 21 was obtained.

As shown in this graph, even if oblique incidence of ± 3 ° with respect to the incident angle of 45 ° is included in addition to the light incident at an incident angle of 45 °, the visible band (400 nm to 70 °) is obtained.
0 nm), and can be efficiently separated into S-polarized light and P-polarized light. The polarization beam splitter thus configured has excellent polarization separation characteristics.

The structure in which the high-refractive-index layer and the low-refractive-index layer are exchanged, that is, (first transparent substrate) | [L / 2 · (L / 2 · H · L / 2)
^m ] · A [(L / 2 · H · L / 2) ⁿ · B [(L / 2 · H
· L / 2) ^P · L / 2] | (second transparent substrate) or (first transparent substrate) | (L / 2 · HL / 2) ^m · A (L
/ 2 · H · L / 2) ⁿ · B (L / 2 · H · L / 2) ^p |
(Second Transparent Substrate) A similar effect was obtained even if the polarizing beam splitter was configured with such a structure as described above.

Further, the values of A and B are not limited to the values "1.22" and "1.48" in the sixth to ninth embodiments. By setting A and B in the range of A ≦ 1.22 and 1.22 <B <1.49, the same effect as in the above embodiment can be obtained.

[0160]

As described above, according to the present invention, whether the polarizing multilayer film is composed of a single alternately laminated film or has a so-called double structure in which two alternately laminated films are superimposed, Alternatively, it is configured so as to satisfy a predetermined inequality according to whether it is a so-called triple structure in which three alternately stacked films are superimposed, so that even if obliquely incident light is included, it covers the entire visible band. In addition, the S component and the P component can be efficiently separated.

In particular, according to the third, sixth and ninth aspects of the present invention, the repetition period of the high refractive index layer and the low refractive index layer is set to 5 or more.
It can be efficiently separated into components.

According to the tenth aspect of the present invention, since the configuration is such that Expression 8 is satisfied, the separation efficiency can be maximized when the angle of incidence on the polarizing beam splitter is 45 °.

According to the illumination optical system of the eleventh aspect,
Since the visible light is efficiently separated into two linearly polarized lights (S-polarized light and P-polarized light) by using the polarizing beam splitter according to any one of claims 1 to 10, the polarizing beam splitter is used. The two separated linearly polarized lights can be efficiently used to illuminate the illuminated object, and the illuminated object can be brightly illuminated.

Further, according to the projector of the thirteenth aspect, by using the polarizing beam splitter according to any one of the first to tenth aspects, visible light can be efficiently converted into two linearly polarized lights (S-polarized light and P-polarized light). And is used for panel illumination, so that the amount of light emitted from the panel can be increased, and as a result, the projected image on the screen can be brightened.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a polarizing beam splitter according to the present invention.
It is sectional drawing which shows embodiment.

FIG. 2 is a diagram illustrating polarization separation characteristics of the polarization beam splitter of FIG.

FIG. 3 is a diagram showing conditions under which good polarization separation characteristics can be obtained in the polarization beam splitter of FIG.

FIG. 4 shows a second example of the polarizing beam splitter according to the present invention.
It is sectional drawing which shows embodiment.

FIG. 5 is a schematic diagram showing the reason why a wide range of separable wavelength bands can be obtained in the polarization beam splitter of FIG.

FIG. 6 is a diagram showing conditions under which good polarization separation characteristics can be obtained in the polarization beam splitter of FIG.

FIG. 7 shows a third embodiment of the polarizing beam splitter according to the present invention.
It is sectional drawing which shows embodiment.

FIG. 8 is a diagram showing conditions under which good polarization separation characteristics can be obtained in the polarization beam splitter of FIG. 7;

FIG. 9 is a diagram showing a configuration of a liquid crystal projector to which the polarization beam splitter according to the present invention is applied.

FIG. 10 is a diagram showing a modification of the illumination optical system.

FIG. 11 is a diagram showing another modification of the illumination optical system.

FIG. 12 is a graph showing the polarization separation characteristics of the polarization beam splitter according to the first example.

FIG. 13 is a graph showing a relationship between a repetition period and polarization separation characteristics in a polarization beam splitter.

FIG. 14 is a graph illustrating the polarization separation characteristics of the polarization beam splitter according to the second example.

FIG. 15 is a graph showing the polarization separation characteristics of the polarization beam splitter according to the third example.

FIG. 16 is a graph showing the polarization separation characteristics of the polarization beam splitter according to the fourth example.

FIG. 17 is a graph showing the polarization separation characteristics of the polarization beam splitter according to the fifth example.

FIG. 18 is a graph showing the polarization separation characteristics of the polarization beam splitter according to the sixth example.

FIG. 19 is a graph illustrating the polarization separation characteristics of the polarization beam splitter according to the seventh example.

FIG. 20 is a graph showing the polarization separation characteristics of the polarization beam splitter according to the eighth example.

FIG. 21 is a graph showing the polarization separation characteristics of the polarization beam splitter according to the ninth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent glass (1st transparent base) 2 Glass plate (2nd transparent base) 3 Polarization multilayer film 6 Light flux (S polarization) 7 Light flux (P polarization) 10b Half-wave plate (conversion part) 31-33 Alternate laminated film 31H, 32H, 33H High refractive index layer 31L, 32L, 33L Low refractive index layer 100 Illumination optical system 200 Color separation optical system 300 Projection optical system 400 Transparent prism (first and second transparent substrates) PBS Polarization beam splitter m, n, p Repetition period

Claims (14)

[Claims] 1. A polarizing beam splitter comprising a polarizing multilayer film sandwiched between first and second transparent substrates having a refractive index of n _G , wherein the polarizing multilayer film comprises a high refractive index layer having a refractive index n _H , a refractive index n _H It is composed of alternately laminated films in which low refractive index layers having a refractive index n _L lower than _H are alternately laminated, and has the following inequality: A polarizing beam splitter characterized by satisfying the following. Wherein the center wavelength of the branching wavelength band and lambda _0, the lambda _0/4 layers of refractive index n _H and H, the refractive index n _L of the lambda ₀ /
When the four layers are L and m is a repetition period, the alternate laminated film is (first transparent substrate) | (H / 2 · L · H / 2) ^m | (second
(Transparent substrate), (first transparent substrate) | H / 2 · (H / 2 · L · H / 2) ^m
.H / 2 | (second transparent substrate), (first transparent substrate) | (L / 2.HL.L / 2) ^m | (second
(Transparent substrate), and (first transparent substrate) | L / 2 · (L / 2 · H · L / 2) ^m
2. The polarizing beam splitter according to claim 1, wherein the polarizing beam splitter has a configuration represented by any one of the following. 3. The polarization beam splitter according to claim 2, wherein said repetition period m is 5 or more. 4. A polarizing beam splitter comprising a polarizing multilayer film sandwiched between first and second transparent substrates having a refractive index of n _G , wherein the polarizing multilayer film comprises: a high refractive index layer having a refractive index of n _H ; _A first alternate laminated film capable of branching light in a wavelength band centered on a center wavelength λ ₀ by alternately laminating low refractive index layers having a refractive index n _L lower than _H and the high refractive index layer and A low-refractive-index layer is alternately laminated, and a second alternate laminated film capable of branching light in a wavelength band centered on the center wavelength λ ₁ (> λ ₀ ) is laminated. Equation 2 A polarizing beam splitter characterized by satisfying the following. 5. The lambda _0/4 layers of refractive index n _H and H, the lambda _0/4 layers of refractive index n _L is L, when the period repeatedly m, n, the the alternate laminated film, ( First transparent substrate) | [H / 2. (H / 2.L.H / 2)
^m ] · A [(H / 2 · L · H / 2) ⁿ · H / 2] | (second
(Transparent substrate), (First transparent substrate) | (H / 2 · L · H / 2) ^mA · (H
/ 2 · L · H / 2) ⁿ | (second transparent base), (first transparent base) | [L / 2 · (L / 2 · H · L / 2)
^m ] · A [(L / 2 · H · L / 2) ⁿ · L / 2] | (second
(Transparent substrate), and (first transparent substrate) | (L / 2 · HL / 2) ^mA (L
/ 2 · H · L / 2) ⁿ | (second transparent substrate), wherein 1.0 <A ≦ 1.38. . 6. The polarization beam splitter according to claim 5, wherein each of the repetition periods m and n is 5 or more. 7. A polarizing beam splitter comprising a polarizing multilayer film sandwiched between first and second transparent substrates having a refractive index of n _G , wherein the polarizing multilayer film comprises: a high refractive index layer having a refractive index of n _H ; _A first alternate laminated film capable of branching light in a wavelength band centered on a center wavelength λ ₀ by alternately laminating low refractive index layers having a refractive index n _L lower than _H and the high refractive index layer and A second alternate laminated film capable of branching light in a wavelength band centered on a center wavelength λ ₁ (> λ ₀ ) by alternately laminating low refractive index layers, the high refractive index layer, and the low refractive index layer; Are alternately laminated, and a third alternately laminated film capable of branching light in a wavelength band centered on the center wavelength λ ₂ (> λ ₁ ) is further laminated, and furthermore, the following inequality: A polarizing beam splitter characterized by satisfying the following. 8. The lambda _0/4 layers of refractive index n _H and H, the lambda _0/4 layers of refractive index n _L and L, m, n, when the period repeated p, the alternate laminated film , (First transparent substrate) | [H / 2 · (H / 2 · L · H / 2)
^m ] · A [(H / 2 · L · H / 2) ⁿ · B [(H / 2 · L
· H / 2) ^p · H / 2] | (second transparent substrate) or (first transparent substrate) | (H / 2 · L · H / 2) ^m · A (H
/ LH / 2) ^nB (H / 2LH / 2) ^p |
(2nd transparent substrate), (1st transparent substrate) | [L / 2 · (L / 2 · H · L / 2)
^m ] · A [(L / 2 · H · L / 2) ⁿ · B [(L / 2 · H
(L / 2) ^p · L / 2] | (second transparent substrate) and (first transparent substrate) | (L / 2 · HL / 2) ^mA (L
/ 2 · H · L / 2) ⁿ · B (L / 2 · H · L / 2) ^p |
The polarizing beam splitter according to claim 7, wherein the second transparent substrate has a configuration represented by any one of 1.0 <A ≦ 1.22 and 1.22 <B <1.49. 9. The repetition cycle m, n, p is 5
9. The polarization beam splitter according to claim 8, wherein: 10. The following equation: The polarizing beam splitter according to any one of claims 1 to 9, further satisfying the following. 11. An illumination optical system for generating visible light having a uniform polarization direction, comprising: a polarizing beam splitter according to claim 1; and a visible light having a visible band. An illumination, comprising: a light source that causes the visible light to enter the polarization beam splitter; and a conversion unit that converts one polarization direction of the two linearly polarized lights separated by the polarization beam splitter into the other polarization direction. Optical system. 12. The illumination optical system according to claim 11, wherein an incident angle of the visible light on the polarization beam splitter is 45 °. 13. An illumination optical system for generating visible light having a uniform polarization direction, and after separating the visible light from the illumination optical system into a plurality of primary color lights, irradiating each of the primary color lights to a corresponding panel. A color separation optical system, and a projection optical system that guides color component lights emitted from the plurality of panels onto a screen while aligning optical axes, and projects an image formed on the panel on the screen. In the projector, the illumination optical system generates the polarization beam splitter according to any one of claims 1 to 10, and a light source that generates visible light having a visible band and makes the visible light incident on the polarization beam splitter. And a converter for converting one polarization direction of the two linearly polarized lights separated by the polarization beam splitter into the other polarization direction. 14. The projector according to claim 13, wherein an incident angle of the visible light on the polarization beam splitter is 45 °.