JP2002214434A - Method for designing polarized light separating film, polarized light separating element with polarized light separating film by the method, polarized light converting element and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for designing a polarized light separating film for enhancing transmittance and reflectance, a polarized light separating element with a polarized light separating film designed by the method, a polarized light converting element with the polarized light separating element and a projection display device using the polarized light converting element. SOLUTION: In the method for designing a polarized light separating film 20 as a component of a polarized light separating element 330 for separating incident light into two sorts of polarized lights, the distribution of incident angle of light incident on the polarized light separating film 20 is obtained and the thickness of each layer of the film 20 is obtained according to the distribution. The polarized light separating element 330 is formed by incorporating the polarized light separating film 20 designed by the method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for designing a polarization separation film used in a polarization separation element for separating incident light into two kinds of polarized light, a polarization separation element provided with the polarization separation film, The present invention relates to a polarization conversion element provided with the polarization separation element, and a projection display device using the polarization conversion element.

[0002]

2. Description of the Related Art In a projection display device, an element called a light valve is used to modulate light in accordance with an image signal. As the light valve, a type that uses one type of linearly polarized light, such as a transmissive liquid crystal panel or a reflective liquid crystal panel, is often used. In a projection display device using one type of linearly polarized light, from the viewpoint of improving light use efficiency, a polarization conversion element for converting unpolarized incident light emitted from a light source into one type of linearly polarized light is used. May be provided. In this case, the polarization conversion element is a polarization separation element (PBS) for separating incident light into two types of polarized light and a selection for converting one of the two types of polarized light to the other polarized light. A phase difference plate is provided. That is, in the projection display device, the light (non-polarized light) of the lamp is separated into P-polarized light and S-polarized light, and thereafter, all the light from the lamp is converted by converting the P-polarized light into S-polarized light. Align with S-polarized light. Since a polarizing plate that transmits S-polarized light is attached to the light valve (liquid crystal panel), the use efficiency of the emitted light of the lamp is improved by this polarization conversion. Typically, 50% of the light is absorbed by the polarizing plate.)

[0003] The above-mentioned polarized light separating element is composed of an intermediate refraction material (n
= Approximately 1.7) and a low refractive index material (approximately n = 1.4)
The polarization separation film (PBS multilayer film) is composed of a multilayer film (about 40 to 50 layers in total) in which the above layers are alternately stacked. The thickness of each layer of the polarization splitting film is determined based on simulation optimization conditions, and is formed by deposition using a vapor deposition machine. The ideal conditions for the optimization at this time are: P-wave transmittance 100%, S-wave transmittance 0%
(Reflectance: 100%), and the polarization separation film at that time is set at 45 ° with respect to the incident surface, and is designed on the assumption that the incident angle of the incident light on the polarization separation film is 45 °. I have.

[0004]

FIG. 11 is a characteristic diagram of the P-wave transmittance at each incident angle (41 ° to 49 °) with respect to the polarization splitting film, and FIG. 12 is a graph showing each incident angle (41 °) with respect to the polarization splitting film. FIG. 47 is a characteristic diagram of the S-wave reflectance in the case of ゜ 49 °). In any case, when the incident angle deviates from 45 °, the characteristics are deteriorated. .

On the other hand, in the current optical system of the projection display device, it is impossible to completely convert the light emitted from the lamp into a parallel light beam, and the light incident on the polarization splitting element varies. For this reason, the incident light to the polarization splitting film of the polarization splitting element also varies with respect to the set incident angle of 45 °, so that the deterioration of the characteristics cannot be avoided.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a method of designing a polarization separation film for improving transmittance and reflectance, and a polarization separation film designed by the design method. An object of the present invention is to provide a polarization beam splitter having a base film, a polarization beam splitter provided with the polarization beam splitter, and a projection display device using the polarization beam splitter.

[0007]

(1) A method for designing a polarization splitting film according to one aspect of the present invention is a method for designing a polarization splitting element for splitting incident light into two types of polarized light. In the design method of the separation film, the distribution of the incident angle of light incident on the polarization separation film is obtained, and the thickness of each layer of the polarization separation film is obtained based on the distribution of the incident angle. In the present invention, the distribution of the incident angle of light incident on the polarization separation film is obtained, and the thickness of each layer of the polarization separation film is obtained based on the distribution of the incident angle. And the reflectance can be improved. For this reason, the light utilization rate is increased.

(2) In the method for designing a polarization beam splitting film according to another aspect of the present invention, in the above method (1), the distribution of the incident angle is obtained by actual measurement or simulation. In the present invention, since the distribution of the incident angle is obtained by actual measurement or simulation, the actual incident angle distribution can be reflected in the design of the polarization separation film, and the transmittance and the reflectance of the polarization separation film are improved. be able to.

(3) The method for designing a polarization beam splitting film according to another aspect of the present invention is the method of (1) or (2),
The thickness of each layer of the polarization separation film is determined based on the incident angle having the largest relative intensity in the distribution of the incident angle.

(4) A polarization beam splitting element according to another aspect of the present invention is a polarization beam splitting element for separating incident light into two kinds of polarized light beams. A polarization separation film and a reflection film are alternately arranged between the optical substrates, and the polarization separation film is designed by the design method according to any one of the above (1) to (3). In the present invention, the polarization separation film designed by the design method according to any one of the above (1) to (3) is used, and therefore, the transmittance and the reflectance of the polarization separation film are improved. Therefore, the amount of light emitted from the polarization separation element is increased, and the light utilization rate is increased.

(5) The polarization beam splitting element according to another aspect of the present invention is the polarization beam splitting element according to the above (4), wherein the polarization beam splitting film and the reflection film are respectively arranged at an angle of 45 ° with respect to the incident surface. ing. In the present invention, when light is incident, for example, vertically on the incident surface of the polarization separation element, the light is incident on the polarization separation film at an incident angle of 45 °, and transmits, for example, P-polarized light and reflects S-polarized light. Then, the S-polarized wave is applied to the reflection film by 45.
The light enters at an incident angle of ゜ and is reflected in a direction perpendicular to the incident surface of the polarization splitting element.

(6) A polarization beam splitting element according to another aspect of the present invention is the polarization beam splitting element according to the above (4) or (5),
The polarization splitting film transmits the P-polarized wave and reflects the S-polarized wave in the incident light, and the reflective film reflects the S-polarized wave. In the present invention, when light is incident on the incident surface of the polarization separation element, the polarization separation film transmits S-polarized light and reflects P-polarized light. Then, the P-polarized wave enters the reflection film and is reflected.

(7) The polarized light separating element according to another aspect of the present invention is the polarized light separating element according to (4) or (5) above.
The polarization splitting film transmits the S-polarized wave of the incident light and reflects the P-polarized wave, and the reflective film reflects the P-polarized wave. In the present invention, when light is incident on the incident surface of the polarization separation element, the polarization separation film transmits S-polarized light and reflects P-polarized light. Then, the P-polarized wave enters the reflection film and is reflected.

(8) A polarization conversion element according to another aspect of the present invention is a polarization conversion element for converting incident light into one kind of polarized light, wherein any one of the above (4) to (7) is used. And a selective phase difference plate that converts one of the two types of polarized light from the polarized light separating element into the other polarized light. In the present invention, when light enters the polarization separation element, it is divided into two types of polarized light (P-polarized light,
(S-polarized wave). Then, the incident light is converted into one type of polarized light by converting one of the two types of polarized light (for example, an S-polarized wave) into the other type of polarized light (a P-polarized wave) using a selective retardation plate. Output.

(9) A projection display apparatus according to another aspect of the present invention includes a light source section, a polarization conversion element that converts light emitted from the light source section into substantially one type of polarized light, The polarization conversion device includes a modulation unit that modulates light based on a given image signal and a projection optical unit that projects the light modulated by the modulation unit, and the polarization conversion element includes the polarization conversion element described in (8). In the present invention, the polarization conversion element converts light emitted from the light source unit into one type of polarized light, and the modulation means modulates the light from the polarization conversion element based on the given image signal, and the projection optical means. Project the light modulated by the modulation means to generate an image. Since the polarization splitting film of the polarization splitting element is designed to obtain the distribution of the incident angle of the incident light with respect to the polarization splitting film, the polarization splitting film functions with high efficiency and the deterioration of the separation characteristics is suppressed. For this reason,
Also in the image generated by the projection optical means, a decrease in brightness and a decrease in color purity are suppressed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. FIG. 1 is an explanatory diagram illustrating a configuration of a polarization conversion element according to Embodiment 1 of the present invention.
FIG. 1A is a plan view of the polarization conversion element 320, and FIG. 1B is a perspective view of the polarization conversion element 320. The polarization conversion element 320 separates the incident light into P-polarized light and S-polarized light and emits the polarized light. The polarization conversion element 320 converts the two types of linearly polarized light separated by the polarization separation element 330 into one type of light. A λ / 2 retardation plate 381 for converting the light into linearly polarized light. The λ / 2 phase plate 381 corresponds to the selected phase plate in the present invention.

The polarization separating element 330 has a shape in which first and second light-transmitting substrates (hereinafter, referred to as "substrates") 321 and 322 each having a columnar shape having a parallelogram cross section are alternately bonded. ing. Further, between the substrate 321 and the substrate 322, a polarization separation film (PBS multilayer film) 20 and a reflection film (mirror multilayer film) 30 are alternately arranged. They are arranged at an angle of 45 ° with respect to them.

The polarization conversion element 320 shown in FIG.
When light having a random polarization direction including an S-polarized component and a P-polarized component enters the polarized light separating film 20, the incident light is first separated into S-polarized light and P-polarized light by the polarized light separating film 20. You. The S-polarized light is reflected by the polarization splitting film 20 at a substantially right angle, and is further reflected by the reflective film 30 at a right angle before being emitted. On the other hand, the P-polarized light passes through the polarization separation film 20 as it is. A λ / 2 phase difference plate 381 is disposed on the exit surface of the P-polarized light that has passed through the polarization splitting film 20, and the P-polarized light is converted into S-polarized light and emitted. Therefore, most of the light that has passed through the polarization conversion element 320 is emitted as S-polarized light. When the light emitted from the polarization conversion element 320 is desired to be P-polarized light, the λ / 2 retardation plate 381 is arranged on the emission surface from which the S-polarized light reflected by the reflection film 30 is emitted. I just need.

FIG. 2 is an enlarged sectional view showing a part of the polarization beam splitting film 20. The polarization separating film 20 is formed of a light-transmitting substrate 32.
1 is a dielectric multi-layer film, which is composed of a multi-layer structure part 22 in which two kinds of materials are alternately stacked in a total of 49 layers, and a covering layer 24 formed on the multi-layer structure part 22. I have. The polarization separation film 20 is formed by sequentially laminating one layer on the surface of the substrate 321. The substrate 321 on which the polarization separation film 20 is laminated is bonded to the substrate 322 via the optical adhesive 18. The coating layer 24 has a function of increasing the adhesiveness between the polarization separation film 20 and the substrate 322.

The multilayer structure 22 is formed of a transparent substrate 32.
1, a layer having a relatively low refractive index with respect to the substrate (hereinafter, referred to as an L layer) and a layer having a relatively large refractive index (hereinafter, referred to as an H layer) are formed by lamination. . In the example of FIG. 2, L1, H2, L3, H4,.
9, a total of 49 layers are formed, and a coating layer (M layer) is formed thereon.
24 are formed. As the members of the substrates 321 and 322, a member having a refractive index higher than that of ordinary optical glass is used as described later.
8 or an optical glass such as BK7-S. The material of the L layer of the polarization separation film 20 is MgF ₂ , the material of the H layer is MgO, and the coating layer (M
As the material of the layer), SiO ₂ is used.

Next, the optical separation element 3 having the above configuration
A method for designing the polarization splitting film 20 that forms a part of the component 30 will be described. First, the distribution of the incident angle of the incident light on the polarization separation film 20 is determined. The distribution of the incident angle can be obtained by an actual measurement method or a simulation method.

In the case of actual measurement, an optical system of an actual machine is prepared (in the embodiment of FIG. 9 described later, from the light source lamp 101 to the light shielding plate 315).
A pinhole is placed at a position corresponding to the 0 film surface, and while gradually shifting the position, the amount of light passing through the pinhole is measured and converted into a variation in incident light.

In the simulation method, calculation is performed using commercially available simulation software. For example, after the optical components and the arrangement of the projection display device (liquid crystal projector) are determined, the simulation software is started and their specifications are input, whereby the variation of the incident angle of the incident light on the polarization separation film 20 is obtained. Ask for.

FIG. 3 is a characteristic diagram showing the relationship between the incident angle of the incident light on the polarization separation film 20 and the relative intensity obtained by the above method. As can be seen from the figure, the incident angles are distributed (having a width), and the maximum value of the relative intensity is indicated by the incident angle of 43 ° instead of 45 °. As described above, the polarization separation film 20 is designed by obtaining the incident angle at which the relative intensity has the maximum value (the thickness of each layer of the polarization separation film 20 is obtained).

In order to determine the thickness of each layer of the polarization separation film 20, for example, Film * Star (manufacturer name: FT) is used here.
G Software Associates (POBox 579 Princeton, NJ, 0
8542)), commercially available software is used, and the input data and output data when using the software are as follows. (1) Input data Data necessary for simulation of film characteristics a. Dispersion data of substrate (dispersion data is a wavelength characteristic of refractive index) b. Dispersion data of vapor deposition chemical used c. Film thickness (initial value) d. Angle of incidence on thin film e. Polarization direction (P wave or S wave) f. Center wavelength

Data required for membrane optimization g. Required film characteristics (transmittance or reflectance for each wavelength and its allowable value) h. Layers that may be changed at the time of optimization (for example, of the 50 layers, the first to 49th layers may be changed, but the 50th layer is not changed, etc.). It is assumed that the film thickness (initial value) is automatically changed so as to satisfy required characteristics.

(2) Output data Film thickness data Spectral data (transmittance or reflectance (numerical value / graph) for each wavelength)

(3) Input data of this embodiment a. Substrate material: BK7 dispersion data b. Dispersion data of vapor deposition chemicals H: MgO (magnesium oxide) L: MgF ₂ (magnesium fluoride) M: SiO ₂ (silicon dioxide) H, L, and M represent a high refractive index, a low refractive index, and an intermediate refractive index, respectively. The shared data of a and b is a value as shown in FIG. c. Film thickness (initial value): Enter a past design example d. Angle of incidence on thin film: "43 °" is input here.
(45 ° as a comparative example) e. Polarization direction: calculated for P and S respectively f. Central wavelength: 600 nm g. Required film characteristics: Input a target value corresponding to the wavelength region and its allowable value. h. Layers that may be changed: 1 to 49 layers (or 1 to 45 layers)
(The 50th layer (or the 46th layer) is provided for the purpose of improving the adhesiveness to the adhesive, and is not changed if the thickness is too small.)

(4) Output data of this embodiment Film thickness data: Thin film data (1 to 5) shown in the following Table 1.
0 layer). In Table 1, "BK7 / PBS
“Multilayer / BK7” means that the medium before and after the PBS multilayer is P
B7 (one type of optical glass)
Light that has passed through BK7 exits the PBS multilayer film and
It is emitted to K7. Λ / 4 = 1 means that the design wavelength is λ
(= 600 nm), 600/4 = 150 nm
Is “1”. Further, the data in Table 1 is the optical thickness of each layer, and the actual optical thickness is a value obtained by multiplying each data in Table 1 by 150 nm (= D · λ /
4). For example, the layer described as 1.5 L has an optical thickness of 1.5 * 150 = 225 nm.

[0030]

[Table 1]

Tables 2 and 3 below show the characteristics of the amount of transmitted light in the film thickness data of Table 1. These Table 2
From Table 3 and Table 3, when comparing the case where the incident angle is designed at 43 ° and the case where the incident angle is designed at 45 °, the sum of the P-wave transmitted light amount and the S-wave transmitted light amount at the incident angle 43 ° is (754.78 + 79).
3.05 = 1547.83), and P at an incident angle of 45 ° is obtained.
The sum of the wave transmitted light amount and the S wave transmitted light amount is (745.67+
789.76 = 1535.43), and the former is about 1% more efficient than the latter. FIG. 5 shows Table 2.
FIG. 4 is a characteristic diagram showing the characteristics of FIG. As is clear from the figure, the case where the incident angle is designed at 43 ° is 45 °.
It can be seen that the amount of transmitted light is larger than in the case of the design with ゜.

[0032]

[Table 2]

[0033]

[Table 3]

Spectral data: FIG. 6 and FIG.
It is a spectral characteristic when designing at 3 ° and when designing at 45 °.

As is clear from Tables 2 and 3 and FIGS. 5 to 7, it is understood that excellent characteristics are obtained for both the transmittance of the P-wave and the transmittance of the S-wave. Therefore, by using the polarization separation film 20, it is possible to manufacture the polarization separation element 330 that transmits P-polarized light in the visible region and reflects S-polarized light with high efficiency. For this reason, if the number of thin films of the polarization separation film 20 is fixed, a brighter screen can be obtained as compared with the conventional one. This means that, in the case of obtaining a screen having the same brightness as the conventional one, the number of thin films of the polarization separation film 20 can be reduced in the present invention as compared with the conventional one.

Embodiment 2 FIG. FIG. 8 is a schematic configuration diagram showing a main part of a projection display device 800 including the polarization conversion element shown in FIG. The projection display device 800 includes a polarization illuminator 50, dichroic mirrors 801 and 804,
Reflecting mirrors 802, 807, 809 and relay lens 8
06, 808, 810 and three liquid crystal light valves 80
3, 805, 811, a cross dichroic prism 813, and a projection lens 814.

FIG. 9 is a schematic structural view of a principal part of the polarized light illuminating device 50 of FIG. This polarized illumination device 50
Includes a light source unit 60 and a polarization generator 70.
The light source unit 60 emits a light beam having a random polarization direction including an S-polarized component and a P-polarized component. The light beam emitted from the light source unit 60 is one type of linearly polarized light (S-polarized light in the present embodiment) whose polarization direction is almost aligned by the polarization generator 70.
To illuminate the illumination area 80. The illumination area 80 corresponds to the three liquid crystal light valves 803, 805, and 811 in the projection display device of FIG.

The light source section 60 includes a light source lamp 101 and a parabolic reflector 102. Light source lamp 10
The light radiated from 1 is reflected in one direction by the parabolic reflector 102, becomes a substantially parallel light flux, and enters the polarization generator 70.

The polarization generator 70 is provided for the first optical element 20.
0 and a second optical element 400. FIG.
4 is a perspective view of the first optical element 200. FIG. The first optical element 200 has a configuration in which minute light beam splitting lenses 201 having a rectangular outline are arranged in a matrix of M rows in the vertical direction and 2N columns in the horizontal direction. Therefore, there are N columns to the left and N columns to the right from the center line CL in the lateral direction of the lens. In this example, M = 10 and N = 4. The first optical element 200 has an optical axis of the first optical element 2.
It is arranged so as to coincide with the center of 00. The external shape of each light beam splitting lens 201 as viewed from the Z direction is set to be similar to the shape of the illumination area 80. In the present embodiment, since the illumination region 80 has a horizontally long shape that is long in the x direction, the outer shape of the light beam splitting lens 201 on the XY plane is also horizontally long.

The second optical element 400 (FIG. 9) includes an optical element 300 and an exit lens 390. The optical element 300 and the emission-side lens 390 are arranged such that the centers thereof coincide with the optical axis.

The optical element 300 includes the condenser lens array 31
0, a light shielding plate 315, and two polarization conversion elements 320a,
320b (see FIG. 1). The condensing lens array 310 is a lens array having the same configuration as the first optical element 200, and is arranged in a direction facing the first optical element 200. The condensing lens array 310 condenses the plurality of split light beams split by the respective light beam splitting lenses 201 together with the first optical element 200, and the polarization conversion elements 320a, 3
20b. The polarization conversion element 320a,
Reference numeral 320b denotes an arrangement in which two polarization conversion elements having the configuration shown in FIG. 1 are arranged such that the respective polarization separation films and reflection films face each other. The polarization conversion element 32
0a and 320b are the polarization separation elements 33 as described above.
The λ / 2 phase difference plate 381 is selectively disposed on the emission surfaces of the reference numerals 0a and 330b. The light-shielding plate 315 is formed by the condenser lens array 310 and the polarization conversion elements 320a and 320b.
This is arranged to prevent light that cannot be condensed on the polarization separation film from directly entering the reflection film. The polarization conversion elements 320a and 320b are provided with the polarization separation film 20 and the reflection film 30 described above. Therefore, the light source unit 60
Can be converted into one type of linearly polarized light (in this embodiment, S-polarized light) with high efficiency and emitted.

The exit lens 390 in FIG.
00, a plurality of split light beams (the polarization conversion element 32
0a and 320b) are superimposed on the illumination area 80, that is, on the liquid crystal light valves 803, 805 and 811.

The dichroic mirrors 801 and 80 shown in FIG.
Reference numeral 4 denotes a light beam emitted from the polarized light illuminating device 50 for red, blue,
It has a function as a color light separation unit that separates into three green color lights. Three liquid crystal light valves 803, 805, 81
Reference numeral 1 has a function as a modulating unit that forms an image by modulating three color lights in accordance with given image information (image signals). Cross dichroic prism 81
Reference numeral 3 has a function as color light combining means for forming a color image by combining three color lights. The projection lens 814 is
It has a function as projection optical means for projecting the light representing the synthesized color image on the screen 815.

A blue light green light reflecting dichroic mirror 801
Transmits the red light component of the light beam emitted from the polarized light illuminating device 50 and reflects the blue light component and the green light component. The transmitted red light is reflected by the reflection mirror 802 and reaches the red light liquid crystal light valve 803. on the other hand,
Of the blue light and the green light reflected by the first dichroic mirror 801, the green light is reflected by the green light reflecting dichroic mirror 804, and the green light liquid crystal light valve 8.
Reach 05. The blue light also passes through the second dichroic mirror 804.

In this embodiment, the optical path length of the blue light is 3
It is the longest of the two colored lights. Therefore, for blue light, after the dichroic mirror 804, a light guide unit 850 including an entrance lens 806, an intermediate lens 808, and an exit lens 810 is provided. That is, after transmitting the blue light through the green light reflecting dichroic mirror 804, first, the incident lens 806 and the reflecting mirror 807
, The light is guided to the intermediate lens 808. Further, the light is reflected by the reflection mirror 809 and guided to the emission lens 810, and reaches the liquid crystal light valve for blue light 811.

The three liquid crystal light valves 803, 805,
811 modulates each color light in accordance with an image signal (image information) provided from an external control circuit (not shown), and generates color light including image information of each color component. These liquid crystal light valves are usually provided with a polarizing plate (not shown) on each of the incident side and the exit side.
Therefore, predetermined polarized light (S-polarized light in this embodiment)
Only the light passes through the polarizer on the incident side of the liquid crystal light valve and is modulated.

The modulated three color lights enter a cross dichroic prism 813. In the cross dichroic prism 813, a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape. The three color lights are combined by these dielectric multilayer films to form light representing a color image. The synthesized light is projected on a screen 815 by a projection lens 814 as a projection optical system, and an image is displayed in an enlarged manner.

The polarized illumination device 50 of the projection display device 800
The polarization conversion element 320 according to the present invention as described above
Since a and b are used, the light is converted into a desired linearly polarized light (in this embodiment, S-polarized light) with high efficiency and emitted. Therefore, such a polarization conversion element 320
In the projection display device having the a and 320b, the brightness of the image projected on the screen 815 can be increased.

Embodiment 3 FIG. In the above-described embodiment, an example has been described in which the polarization separation film transmits the P-polarized light and reflects the S-polarized wave, and the reflection film reflects the S-polarized wave. Alternatively, the P-polarized wave may be used by transmitting the S-polarized wave and reflecting the P-polarized wave, so that the reflection film reflects the P-polarized wave.

[0050]

As described above, according to the present invention, the distribution of the incident angle of light incident on the polarization separation film is obtained, and the thickness of each layer of the polarization separation film is obtained based on the distribution of the incident angle. Therefore, the transmittance and the reflectance of the polarization separation film can be improved. For this reason, the utilization of light of the polarization separation element and the polarization conversion element using the polarization separation film is also increased.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a polarization conversion element according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a part of a polarization splitting film of the polarization conversion element of FIG.

FIG. 3 is a characteristic diagram showing a relationship between an incident angle of light incident on the polarization splitting film of FIG. 1 and a relative intensity.

FIG. 4 is a graph of shared data used in the first embodiment.

FIG. 5 is a characteristic diagram showing characteristics of transmittance with respect to the incident angle when the incident angle is designed to be 43 ° and 45 ° in the first embodiment.

FIG. 6 is a characteristic diagram showing spectral characteristics when the incident angle is designed at 43 ° in the first embodiment.

FIG. 7 is a characteristic diagram showing spectral characteristics when the incident angle is designed at 45 ° in the first embodiment.

FIG. 8 is a schematic configuration diagram illustrating a main part of a projection display device including the polarization conversion element illustrated in FIG. 1;

FIG. 9 is a schematic configuration diagram of a principal part of the polarized light illuminating device of FIG.

FIG. 10 is a perspective view of the first optical element of FIG. 8;

FIG. 11 shows incident angles (41 ° to 49 °) with respect to the polarization splitting film.
It is a characteristic diagram of P wave transmittance in ゜).

FIG. 12 shows incident angles (41 ° to 49 °) with respect to a polarization separation film.
It is a characteristic diagram of S wave reflectance in ゜).

[Explanation of symbols]

 Reference Signs List 20: polarized light separating film 22: multilayer structure part 24: coating layer (M layer) 30: reflective film 320: polarized light conversion element 321, 322: glass substrate with high refractive index 330: polarized light separating element 381: λ / 2 retardation plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 21/00 G03B 21/00 E

Claims (9)

[Claims] 1. A method for designing a polarization separation film constituting a polarization separation element for separating incident light into two types of polarized light, wherein a distribution of incident angles of light incident on the polarization separation film is obtained. A method for designing a polarization separation film, wherein the thickness of each layer of the polarization separation film is determined based on the distribution of the incident angle. 2. The method according to claim 1, wherein the distribution of the incident angle is obtained by actual measurement or simulation. 3. The polarization separation film according to claim 1, wherein the thickness of each layer of the polarization separation film is obtained based on the incident angle having the largest relative intensity in the distribution of the incident angles. Design method. 4. A polarization separating element for separating incident light into two kinds of polarized light, comprising: a plurality of translucent substrates;
4. A polarization separation film and a reflection film, which are alternately arranged between the plurality of light-transmitting substrates, wherein the polarization separation film is provided.
A polarization splitting element designed by the design method according to any one of the above. 5. The polarization separation element according to claim 4, wherein the polarization separation film and the reflection film are arranged at an angle of 45 ° with respect to an incident surface. 6. The polarization separation element according to claim 4, wherein the polarization separation film transmits a P-polarized wave of the incident light and reflects an S-polarized wave, and the reflection film reflects an S-polarized wave. 7. The polarized light separating film according to claim 4, wherein the polarized light separating film transmits an S-polarized wave and reflects a P-polarized wave in the incident light, and the reflecting film reflects the P-polarized wave. Polarization separation element. 8. A polarization conversion device for converting incident light into one type of polarized light, wherein the polarization separation device according to claim 4 and two types of polarization separation devices. And a selective phase difference plate for converting one of the polarized lights into the other polarized light. 9. A light source section, a polarization conversion element that converts light emitted from the light source section into substantially one type of polarized light, and modulates light from the polarization conversion element based on a given image signal. 9. A projection display device comprising: a modulating means for performing the modulation; and a projection optical means for projecting the light modulated by the modulating means, wherein the polarization conversion element comprises the polarization conversion element according to claim 8.