JP5109762B2 - Laminated retardation plate, polarization conversion element, and projection type image device - Google Patents

Description

The present invention relates to a laminated phase difference plate, a polarization conversion element that converts incident light into polarized light, and a projection type video apparatus.

Conventionally, a polarization conversion element including a plurality of translucent base materials, a polarization separation conversion layer, and a reflection film is known (Patent Document 1).
In this polarization conversion element, a crystal plate functioning as a half-wave plate is applied which is constituted by a laminated first crystal plate and second crystal plate. The optical axis azimuth with respect to the X direction of the first quartz plate is 17.5 ° to 27. 27, where X is the direction that is in the incident plane and orthogonal to the traveling direction of the light propagating in the quartz plate. The first and second crystal plates are provided so that the optical axis azimuth angle with respect to the X direction of the second crystal plate is 62.5 ° to 72.5 °.

JP 2007-206225 A

By the way, the half-wave plate of the polarization conversion element needs to have sufficient polarization conversion efficiency and be practical, for example, usable for a projector. This polarization conversion efficiency indicates, for example, the rate of conversion when polarized from the P-polarized component to the S-polarized component. If all the P-polarized components are polarized to the S-polarized component, it is shown as an ideal value of 1.00. . The closer the polarization conversion efficiency is to the ideal value of 1.00, the smaller the loss of the amount of light that has passed through the half-wave plate, and the better the production of a liquid crystal projector that can project a bright image.
In the conventional example shown in Patent Document 1, there is no disclosure of a configuration that makes the polarization conversion efficiency excellent by setting the plate thickness, and the polarization conversion efficiency may not be the best.

An object of the present invention is to provide a laminated phase difference plate, a polarization conversion element, and a projection type video apparatus which have excellent polarization conversion efficiency and have practicality.

本発明の第２の形態に係る積層位相差板は、前記第１、第２位相差板の材料を水晶とし、前記第１、第２結晶光学軸は前記入射面と平行であることを特徴とする。
本発明の第３の形態に係る積層位相差板は、λ１＝４００ｎｍ、λ２＝７００ｎｍとしたときに、前記第１位相差板の厚みｄ１が２１．２μｍ〜５０．０μｍの範囲であり、前記第２位相差板の厚みｄ２が１３．５μｍ〜３１．９μｍの範囲であることを特徴とする。
本発明の第４の形態に係る積層位相差板は、λ１＝４００ｎｍ、λ２＝５００ｎｍとしたときに、前記第１位相差板の厚みｄ１が１６．８μｍ〜４３．７μｍの範囲であり、前記第２位相差板の厚みｄ２が１０．７μｍ〜２７．８μｍの範囲であることを特徴とする。
本発明の第５の形態に係る積層位相差板は、λ１＝５００ｎｍ、λ２＝６００ｎｍとしたときに、前記第１位相差板の厚みｄ１が２１．０μｍ〜５５．６μｍの範囲であり、
前記第２位相差板の厚みｄ２が１３．４μｍ〜３５．４μｍの範囲であることを特徴とする。
本発明の第６の形態に係る積層位相差板は、λ１＝６００ｎｍ、λ２＝７００ｎｍとしたときに、前記第１位相差板の厚みｄ１が２５．３μｍ〜６７．２μｍの範囲であり、前記第２位相差板の厚みｄ２が１６．１μｍ〜４２．８μｍの範囲であることを特徴とする。
本発明の第７の形態に係る偏光変換素子は、第１の主面を光入射面としかつ第２の主面を光出射面とする平板状の積層プリズムと、前記第１及び第２の主面に対し４５°傾斜して間隔をおいて交互に平行配置された偏光分離変換層と反射部とを備え、前記偏光分離変換層は、前記第１の主面側から順に配置された偏光分離部と当該偏光分離部の光出射面側に設けられた波長板とからなり、前記偏光分離部は、前記第１の主面側から入射した光を互いに直交する第１の直線偏光と第２の直線偏光とに分離し、前記第１の直線偏光を透過させかつ前記第２の直線偏光を反射し、前記波長板は、前記偏光分離部を透過した前記第１の直線偏光の振動面を９０°回転させることにより前記第２の直線偏光の振動面と平行な振動面を有する直線偏光に変換して出射させ、前記波長板が、前述の構成の積層位相差板であることを特徴とする。
本発明の第８の形態に係る投射型映像装置は、光源と、前記光源からの光を前記第２の直線偏光に変換して出射する偏光変換素子と、前記偏光変換素子からの出射光を、画像情報に応じて変調する変調手段と、前記変調手段により変調された光を投写する投写光学系と、を有し、前記偏光変換素子が前述の偏光変換素子であることを特徴とする。
本発明の第９の形態に係る投射型映像装置は、前記変調手段が液晶パネルであることを特徴とする。
本発明の第１０の形態に係る投射型映像装置は、光源と、前記光源からの光を前記第２の直線偏光に変換して出射する偏光変換素子と、前記偏光変換素子からの出射光を、画像情報に応じて変調する変調手段と、前記変調手段により変調された光を投写する投写光学系と、を有する投射型映像装置であって、前述の積層位相差板を有することを特徴とする。
［適用例１］
本適用例に係わる偏光変換素子は、光入射面を有し一連に接合された複数の透光基材と、隣接する一対の前記透光基材の第１接合部分に沿って前記光入射面に対して４５°傾斜した状態で挟み込まれた偏光分離変換層と、前記第１接合部分に隣り合う第２接合部分に沿って前記偏光分離変換層と略平行となる状態で挟み込まれた反射膜と、を備え、−１０°〜＋１０°の入射角度で前記光入射面に入射される光を偏光光に変換して射出する偏光変換素子であって、前記偏光分離変換層は、入射される光を２個の偏光成分に分離して一方の偏光成分を透過させるとともに他方の偏光成分を反射させる偏光分離膜と、この偏光分離膜に対して前記光入射面と反対側に配置され前記偏光分離膜を透過した前記一方の偏光成分を他方の偏光成分に変換して透過させる１／２波長板と、を備え、この１／２波長板は、水晶からＹカットで切り出した水晶により板状に形成された第１水晶板および第２水晶板を積層して構成され、前記第１水晶板は、板厚が２１．２μｍ〜５０．０μｍであり、光学軸方位が前記一方の偏光成分の振動面に対してθａａ°回転した方向となる状態で設けられ、前記第２水晶板は、板厚が１３．５μｍ〜３１．９μｍであり、光学軸方位が前記一方の偏光成分の振動面に対してθｂｂ°回転した方向となる状態で設けられ、前記第１水晶板の位相差Γａと、前記第１水晶板の位相差Γａのずれ量ΔΓａと、前記第２水晶板の位相差Γｂと、前記第２水晶板の位相差Γｂのずれ量ΔΓｂと、が式（１）を満たすことを特徴とする。 SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
The laminated phase difference plate according to the first aspect of the present invention is different from the first phase difference plate having the phase difference Γ′a with respect to the light having the wavelength λ incident from the direction of 45 ° with respect to the normal line of the incident surface. A second retardation plate having a phase difference Γ′b is laminated so that the optical axes intersect with each other, and is in a wavelength range of λ1 to λ2 (where λ1 <λ <λ2) with respect to the normal line of the incident surface. The polarization plane of the linearly polarized light incident from the direction of 45 ° is converted into the linearly polarized light rotated by 90 degrees and emitted, and the vibrating surface of the linearly polarized light incident on the first retardation plate is An angle formed between the projection vibration surface projected onto the incident surface and the first crystal optical axis of the first retardation plate is defined as a first optical axis azimuth angle θaa, and the projection vibration surface and the second crystal of the second retardation plate are included. An angle formed with the optical axis is a second optical axis azimuth angle θbb, and the first connection is made on a plane perpendicular to the optical axis of the incident linearly polarized light. An angle formed by the first projected crystal optical axis projected from the optical axis and the incident plane of the linearly polarized light is defined as a first projected optical axis azimuth angle θa, and the second crystal optical axis projected onto the perpendicular plane. When the angle formed between the two projection crystal optical axes and the vibration plane of the incident linearly polarized light is the second projection optical axis azimuth angle θb, the first optical axis azimuth angle θaa and the first projection optical axis azimuth angle θa The relationship
θaa = Atan (tan (θa) / 2 ^1/2 ) is satisfied,
The relationship between the second optical axis azimuth angle θbb and the second projection optical axis azimuth angle θb is
θbb = Atan (tan (θb) / 2 ^1/2 ) is satisfied,
The angle formed between the projection image when the optical axis of the incident linearly polarized light is projected onto the incident surface and the projection vibration surface is a light beam traveling angle θ5, and a direction of 45 ° with respect to the normal of the incident surface, The angle formed by the optical axis of the incident linearly polarized light is defined as an incident angle θ6, and the light ray traveling angle θ5 and the incident angle θ6 satisfy θ5 = 0 °, −10 ° ≦ θ6 ≦ + 10 °,
The relationship between the first projection optical axis azimuth angle θa and the second projection optical axis azimuth angle θb satisfies the condition of θb = θa + α 40 ° <α <50 ° , where α is a set value ,
The phase difference Γ′a and the phase difference Γ′b are set as ΔΓa as a deviation amount from the design target value of the phase difference Γa of the first crystal plate, and from the design target value of the phase difference Γb of the second crystal plate. If the amount of deviation is ΔΓb,
Γ′a = Γa + ΔΓa, Γ′b = Γb + ΔΓb, Γa = 180 °, Γb = 180 °
Satisfied,
The relationship between ΔΓa and ΔΓb satisfies the formula (1).

The laminated phase difference plate according to the second aspect of the present invention is characterized in that the material of the first and second phase difference plates is quartz, and the first and second crystal optical axes are parallel to the incident surface. And
In the laminated retardation plate according to the third aspect of the present invention, when λ1 = 400 nm and λ2 = 700 nm, the thickness d1 of the first retardation plate is in the range of 21.2 μm to 50.0 μm, The thickness d2 of the second retardation plate is in the range of 13.5 μm to 31.9 μm.
In the laminated retardation plate according to the fourth aspect of the present invention, when λ1 = 400 nm and λ2 = 500 nm, the thickness d1 of the first retardation plate is in the range of 16.8 μm to 43.7 μm, The thickness d2 of the second retardation plate is in the range of 10.7 μm to 27.8 μm.
In the multilayer retardation plate according to the fifth aspect of the present invention, when λ1 = 500 nm and λ2 = 600 nm, the thickness d1 of the first retardation plate is in the range of 21.0 μm to 55.6 μm,
The thickness d2 of the second retardation plate is in the range of 13.4 μm to 35.4 μm.
In the laminated retardation plate according to the sixth aspect of the present invention, when λ1 = 600 nm and λ2 = 700 nm, the thickness d1 of the first retardation plate is in the range of 25.3 μm to 67.2 μm, The thickness d2 of the second retardation plate is in the range of 16.1 μm to 42.8 μm.
A polarization conversion element according to a seventh aspect of the present invention includes a flat plate-shaped prism having a first main surface as a light incident surface and a second main surface as a light output surface, and the first and second prisms. A polarization separation / conversion layer and a reflection part that are alternately arranged in parallel at an interval of 45 ° with respect to the main surface, and the polarization separation / conversion layer is polarized light that is sequentially arranged from the first main surface side. And a wave plate provided on the light exit surface side of the polarization separation unit. The polarization separation unit includes a first linearly polarized light orthogonal to the first linearly polarized light and the first light incident from the first main surface side. The first linearly polarized light is transmitted through the first linearly polarized light and the second linearly polarized light is reflected. The wave plate transmits the first linearly polarized light through the polarized light separating unit. Is converted into linearly polarized light having an oscillating plane parallel to the oscillating surface of the second linearly polarized light. The wave plate is a laminated phase difference plate having the above-described configuration.
A projection-type imaging device according to an eighth aspect of the present invention includes a light source, a polarization conversion element that converts the light from the light source into the second linearly polarized light and emits the light, and the light emitted from the polarization conversion element. And a modulation unit that modulates in accordance with image information, and a projection optical system that projects the light modulated by the modulation unit, wherein the polarization conversion element is the polarization conversion element described above.
A projection type video apparatus according to a ninth aspect of the present invention is characterized in that the modulation means is a liquid crystal panel.
A projection-type imaging device according to a tenth aspect of the present invention includes a light source, a polarization conversion element that converts the light from the light source into the second linearly polarized light and emits the light, and the light emitted from the polarization conversion element. A projection type video apparatus comprising: a modulation unit that modulates according to image information; and a projection optical system that projects light modulated by the modulation unit. To do.
[Application Example 1]
The polarization conversion element according to this application example includes a plurality of light-transmitting base materials that have a light incident surface and are joined in series, and the light incident surface along a first joint portion of a pair of adjacent light-transmitting substrates. A polarization separation / conversion layer sandwiched in a state inclined by 45 ° with respect to the first separation portion, and a reflection film sandwiched in a state substantially parallel to the polarization separation / conversion layer along a second junction portion adjacent to the first junction portion A polarization conversion element that converts light incident on the light incident surface at an incident angle of −10 ° to + 10 ° into a polarized light and emits the polarized light, and the polarization separation / conversion layer is incident A polarization separation film that separates light into two polarization components, transmits one polarization component and reflects the other polarization component, and is disposed on the opposite side of the light incident surface with respect to the polarization separation film. The one polarized component transmitted through the separation membrane is converted into the other polarized component. A half-wave plate that transmits light, and the half-wave plate is formed by laminating a first crystal plate and a second crystal plate that are formed in a plate shape from a crystal cut out from a crystal by a Y-cut. The first crystal plate has a plate thickness of 21.2 μm to 50.0 μm, and is provided in a state where the optical axis direction is a direction rotated by θaa ° with respect to the vibration surface of the one polarization component. The two quartz plates have a plate thickness of 13.5 μm to 31.9 μm, and are provided in a state where the optical axis direction is a direction rotated by θbb ° with respect to the vibration surface of the one polarization component, The phase difference Γa of the first crystal plate, the shift amount ΔΓa of the phase difference Γa of the first crystal plate, the phase difference Γb of the second crystal plate, and the shift amount ΔΓb of the phase difference Γb of the second crystal plate 1) is satisfied.

In this application example, the half-wave plate constituting the polarization separation / conversion layer of the polarization conversion element is composed of the stacked first crystal plate and second crystal plate. The thickness of the first crystal plate is 21.2 μm to 5
The optical axis direction is set to 0.0 μm, for example, θaa with respect to the vibration plane of the P-polarized component
It is provided in a state in which it is rotated (a state in which the optical axis azimuth is θaa °, hereinafter referred to as a first optical axis azimuth). Further, the plate thickness of the second crystal plate is set to 13.5 μm to 31.9 μm, and the optical axis azimuth (hereinafter referred to as second optical axis azimuth) is set to θbb °. When this half-wave plate is provided in a state inclined by 45 ° with respect to the light incident surface of the translucent substrate, θaa ° = 16.3 ° and θbb ° = 59.6 °.
Therefore, the optical axis azimuth angle (hereinafter referred to as the first crystal optical axis azimuth angle) when the optical axis of the first crystal plate is projected from the light incident direction onto the light exit surface parallel to the light incident surface of the translucent substrate. 22.5)
° can be. Furthermore, the optical axis azimuth angle (hereinafter referred to as the second projection optical axis azimuth angle) when the optical axis of the second quartz plate is projected from the light incident direction on the light exit surface is set to 67.5 °. Can do. Therefore, in this polarization conversion element, the incident light is incident on the light incident surface at an incident angle of −10 ° to + 10 °, and the half-wave plate has the first and second optical axis azimuth angles of 16.6. 3 °
, 59.6 ° (hereinafter referred to as an incident light-corresponding state), the average polarization conversion efficiency (hereinafter referred to as the following) in the three-color wavelength band (wavelength: 400 nm to 700 nm) in the half-wave plate
(Referred to as three-color polarization conversion efficiency) can be 0.8 or more.

In addition, the first crystal plate and the second crystal plate polish the crystal base material cut from the quartz crystal, and the thickness of the substrate before bonding is processed to the target value of the designed thickness. The deviation amount between the processed thickness value and the designed thickness target value affects the deviation amount between the first crystal plate and the target value of the phase difference of the light beam transmitted through the second crystal plate. If the phase difference of the second crystal plate is controlled with respect to the amount of deviation from the target value of the phase difference of the first crystal plate, the amount of deviation from the target value of the phase difference of the light beam transmitted through the polarization conversion element after bonding. The polarization conversion efficiency can be improved.
Therefore, the amount of deviation ΔΓb from the design target value of the phase difference Γb of the second crystal plate is calculated from the amount of deviation ΔΓa from the design target value of the phase difference Γa of the first crystal plate and the optical axis azimuth angle θb of the second crystal plate. As a means for obtaining, the above formula (1) was found. By this means, when the quartz plates are bonded, the first quartz plate having the deviation ΔΓa from the design target value of the phase difference Γa and the deviation ΔΓb from the design target value of the optimum phase difference Γb are obtained. And a second crystal plate having the same. The polarization conversion element obtained by this means has a deviation amount ΔΓ from the design target value of the phase difference Γa.
Since a is offset by the amount of deviation ΔΓb from the design target value of the phase difference Γb, high polarization conversion efficiency can be achieved.

Here, when the polarization conversion element is used for a projector, generally, the illumination optical axis in the design of the projector and the light incident surface of the polarization conversion element are orthogonal to each other on the light exit side of the lens array. That is, the incident light emitted from the lens array is incident on the light incident surface of the translucent substrate at an incident angle of 0 ° and is incident on the half-wave plate at an incident angle of 45 °. . In such a configuration, the light emitted from the lens array is incident on the polarization conversion element at an incident angle of −10 ° to + 10 ° depending on the focal position of the lens array.
Furthermore, when the relationship between the three-color polarization conversion efficiency of the half-wave plate and the projection state of the image by the projector using this half-wave plate is examined, the three-color polarization conversion efficiency is 0.8 or more. For example, it has been confirmed that an image having a reproducibility of a blue component, a green component, and a red component at a level having no practical problem can be projected without causing a problem.
From the above, even when the polarization conversion element of the present invention is installed on the light exit side of the lens array in the projector, that is, when incident light is incident at an incident angle of −10 ° to + 10 °, 1 In the / 2 wavelength plate, incident light in the three-color wavelength band can be converted into polarized light with a three-color polarization conversion efficiency of 0.8 or more, and a practical polarization conversion element can be provided.

[Application Example 2]
The polarization conversion element according to this application example includes a plurality of light-transmitting base materials that have a light incident surface and are joined in series, and the light incident surface along a first joint portion of a pair of adjacent light-transmitting substrates. A polarization separation / conversion layer sandwiched in a state inclined by 45 ° with respect to the first separation portion, and a reflection film sandwiched in a state substantially parallel to the polarization separation / conversion layer along a second junction portion adjacent to the first junction portion And −10
A polarization conversion element that converts light having a wavelength of 400 nm to 500 nm, which is incident on the light incident surface at an incident angle of ° to + 10 °, into polarized light and emits the light, and the polarization separation / conversion layer includes incident light Is separated into two polarization components, one polarization component is transmitted and the other polarization component is reflected, and a polarization separation film disposed on the opposite side of the light incident surface with respect to the polarization separation film. A half-wave plate that converts the one polarization component transmitted through the film into the other polarization component and transmits the other polarization component, and the half-wave plate is formed into a plate shape by a crystal cut from a crystal by a Y-cut. The first crystal plate and the second crystal plate that are formed are laminated, and the first crystal plate has a plate thickness of 16.8 μm to 43.7 μm, and the optical axis direction is vibration of the one polarization component. State rotated by θaa ° relative to the surface Provided, said second quartz plate, the plate thickness 10.7μm~
27.8 μm, the optical axis direction is provided in a state rotated by θbb ° with respect to the vibration plane of the one polarization component, the phase difference Γa of the first crystal plate, and the first crystal plate The shift amount ΔΓa of the phase difference Γa, the phase difference Γb of the second crystal plate, and the shift amount ΔΓb of the phase difference Γb of the second crystal plate satisfy the above formula (1).

In this application example, the thickness and the first optical axis azimuth of the first crystal plate constituting the half-wave plate are set to 16.8 μm to 43.7 μm and θaa ° = 16.3 °, respectively. 2 The thickness of the quartz plate and the second optical axis azimuth are 10.7 μm to 27.8 μm, θbb ° =
Since the angle is set to 59.6 °, the azimuth angles of the first and second projection optical axes are 22.5 ° and 6 °, respectively.
It can be 7.5 °. Therefore, when the polarization conversion element is installed in a state corresponding to incident light (this half-wave plate is inclined by 45 ° with respect to the light incident surface of the translucent substrate), the blue wavelength band ( The average polarization conversion efficiency (hereinafter referred to as blue polarization conversion efficiency) at a wavelength of 400 nm to 500 nm) can be 0.8 or more. Moreover, a polarization conversion element with high polarization conversion efficiency can be obtained by manufacturing a polarization conversion element based on the formula (1).
Here, when the relationship between the blue polarization conversion efficiency of the half-wave plate and the projection state of the image was examined, if the blue polarization conversion efficiency is 0.8 or more, a blue component at a level that is not practically problematic. It has been confirmed that it is possible to project an image having a reproducibility and brightness with no problem.
From the above, even when the polarization conversion element of the present invention is installed on the light exit side of the lens array in the projector and incident light is incident at an incident angle of −10 ° to + 10 °, 1
In the / 2 wavelength plate, incident light in the blue wavelength band can be converted to polarized light with a blue polarization conversion efficiency of 0.8 or more, and a practical polarization conversion element can be provided.

[Application Example 3]
The polarization conversion element according to this application example includes a plurality of light-transmitting base materials that have a light incident surface and are joined in series, and the light incident surface along a first joint portion of a pair of adjacent light-transmitting substrates. A polarization separation / conversion layer sandwiched in a state inclined by 45 ° with respect to the first separation portion, and a reflection film sandwiched in a state substantially parallel to the polarization separation / conversion layer along a second junction portion adjacent to the first junction portion And −10
A polarization conversion element that converts light having a wavelength of 500 nm to 600 nm, which is incident on the light incident surface at an incident angle of ° to + 10 °, into polarized light, and emits the polarized light. Is separated into two polarization components, one polarization component is transmitted and the other polarization component is reflected, and a polarization separation film disposed on the opposite side of the light incident surface with respect to the polarization separation film. A half-wave plate that converts the one polarization component transmitted through the film into the other polarization component and transmits the other polarization component, and the half-wave plate is formed into a plate shape by a crystal cut from a crystal by a Y-cut. The first crystal plate and the second crystal plate thus formed are laminated, and the first crystal plate has a plate thickness of 21.0 μm to 55.6 μm, and the optical axis direction is vibration of the one polarization component. State rotated by θaa ° relative to the surface Provided, said second quartz plate, the plate thickness 13.4μm~
35.4 μm, and the optical axis direction is provided in a state rotated by θbb ° with respect to the vibration plane of the one polarization component, the phase difference Γa of the first crystal plate, and the first crystal plate The shift amount ΔΓa of the phase difference Γa, the phase difference Γb of the second crystal plate, and the shift amount ΔΓb of the phase difference Γb of the second crystal plate satisfy the above formula (1).

In this application example, the thickness and the first optical axis azimuth of the first crystal plate constituting the half-wave plate are set to 21.0 μm to 55.6 μm and θaa ° = 16.3 °, respectively. 2 The thickness of the quartz plate and the second optical axis azimuth are 13.4 μm to 35.4 μm, θbb ° =
Since the angle is set to 59.6 °, the azimuth angles of the first and second projection optical axes are 22.5 ° and 6 °, respectively.
It can be 7.5 °. Accordingly, when the polarization conversion element is installed in a state corresponding to incident light (this half-wave plate is inclined by 45 ° with respect to the light incident surface of the translucent substrate), the green wavelength band ( The average polarization conversion efficiency (hereinafter referred to as green polarization conversion efficiency) at a wavelength of 500 nm to 600 nm can be 0.8 or more. Moreover, a polarization conversion element with high polarization conversion efficiency can be obtained by manufacturing a polarization conversion element based on the formula (1).
Here, when the relationship between the green polarization conversion efficiency of the half-wave plate and the projection state of the image was examined, if the green polarization conversion efficiency is 0.8 or more, a green component at a level that is practically not problematic. It has been confirmed that it is possible to project an image having a reproducibility and brightness with no problem.
From the above, even when the polarization conversion element of the present invention is installed on the light exit side of the lens array in the projector and incident light is incident at an incident angle of −10 ° to + 10 °, 1
In the / 2 wavelength plate, incident light in the green wavelength band can be converted to polarized light with a green polarization conversion efficiency of 0.8 or more, and a practical polarization conversion element can be provided.

[Application Example 4]
The polarization conversion element according to this application example includes a plurality of light-transmitting base materials that have a light incident surface and are joined in series, and the light incident surface along a first joint portion of a pair of adjacent light-transmitting substrates. A polarization separation / conversion layer sandwiched in a state inclined by 45 ° with respect to the first separation portion, and a reflection film sandwiched in a state substantially parallel to the polarization separation / conversion layer along a second junction portion adjacent to the first junction portion And −10
A polarization conversion element that converts light having a wavelength of 600 nm to 700 nm incident on the light incident surface at an incident angle of 0 to + 10 ° into polarized light and emits the polarized light, and the polarization separation / conversion layer includes incident light. Is separated into two polarization components, one polarization component is transmitted and the other polarization component is reflected, and a polarization separation film disposed on the opposite side of the light incident surface with respect to the polarization separation film. A half-wave plate that converts the one polarization component transmitted through the film into the other polarization component and transmits the other polarization component, and the half-wave plate is formed into a plate shape by a crystal cut from a crystal by a Y-cut. The formed first crystal plate and second crystal plate are laminated, and the first crystal plate has a thickness of 25.3 μm to 67.2 μm, and the optical axis direction is vibration of the one polarization component. State rotated by θaa ° relative to the surface Provided, said second quartz plate, the plate thickness 16.1μm~
42.8 μm, and the optical axis direction is provided in a state rotated by θbb ° with respect to the vibration plane of the one polarization component, the phase difference Γa of the first crystal plate, and the first crystal plate The shift amount ΔΓa of the phase difference Γa, the phase difference Γb of the second crystal plate, and the shift amount ΔΓb of the phase difference Γb of the second crystal plate satisfy the above formula (1).

In this application example, the thickness and the first optical axis azimuth of the first crystal plate constituting the half-wave plate are set to 25.3 μm to 67.2 μm and θaa ° = 16.3 °, respectively. 2 The thickness of the quartz plate and the second optical axis azimuth are 16.1 μm to 42.8 μm, θbb ° =
Since the angle is set to 59.6 °, the azimuth angles of the first and second projection optical axes are 22.5 ° and 6 °, respectively.
It can be 7.5 °. Therefore, when the polarization conversion element is installed in a state corresponding to incident light (this half-wave plate is inclined by 45 ° with respect to the light incident surface of the translucent substrate), the red wavelength band ( The average polarization conversion efficiency (hereinafter referred to as red polarization conversion efficiency) at a wavelength of 600 nm to 700 nm can be made 0.8 or more. Moreover, a polarization conversion element with high polarization conversion efficiency can be obtained by manufacturing a polarization conversion element based on the formula (1).
Here, when the relationship between the red polarization conversion efficiency of the half-wave plate and the projection state of the image was examined, if the red polarization conversion efficiency is 0.8 or more, a red component at a level that has no practical problem. It has been confirmed that it is possible to project an image having a reproducibility and brightness with no problem.
From the above, even when the polarization conversion element of the present invention is installed on the light exit side of the lens array in the projector and incident light is incident at an incident angle of −10 ° to + 10 °, 1
In the / 2 wavelength plate, incident light in the red wavelength band can be converted to polarized light with a red polarization conversion efficiency of 0.8 or more, and a practical polarization conversion element can be provided.

[Application Example 5]
The projector according to this application example includes a light source device, the polarization conversion element according to any one of claims 1 to 4 that converts the light emitted from the light source device into polarized light, and emits the polarized light, and the polarization conversion device. A light modulation device that modulates polarized light formed by the element according to image information to form an optical image, and a projection optical device that enlarges and projects the optical image formed by the light modulation device. Features.
In this application example, it is possible to provide a projector that can achieve the above-described effects.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings. In the first embodiment, a polarization conversion element having a half-wave plate having a three-color polarization conversion efficiency of 0.8 or more will be described.
1A and 1B are schematic views showing configurations of polarization conversion elements according to the first embodiment and second to fourth embodiments to be described later. FIG. 1A is a cross-sectional view, and FIG. 1B is an enlarged view of a Q portion of FIG. FIG.

As shown in FIG. 1A, the polarization conversion element 6 has a substantially rectangular parallelepiped shape. The polarization conversion element 6 includes a plurality of first light transmissive substrates 61, a plurality of second light transmissive substrates 62, a plurality of polarization separation conversion layers 63, and a plurality of reflective films 65.

The 1st, 2nd translucent base materials 61 and 62 are formed in the substantially parallelogram block shape using the translucent material. As materials of the first and second light-transmitting substrates 61 and 62, borosilicate glass,
Examples thereof include glass formed using an inorganic material such as BK7, white plate glass, blue plate glass, quartz glass, and sapphire glass.
The first light transmissive substrate 61 includes a first light incident surface 611 and a first light exit surface 612 that are substantially parallel to each other,
There are provided a first inclined end surface 613 and a second inclined end surface 614 provided in a state of being substantially parallel to each other and an angle formed by the first light incident surface 611 being 45 °. The second light transmissive substrate 62 is also
Having the same configuration as the first light transmissive substrate 61, a second light incident surface 621, a second light emitting surface 622,
A third inclined end surface 623 and a fourth inclined end surface 624 are provided.
And the 1st, 2nd translucent base materials 61 and 62 are alternately arrange | positioned along the longitudinal direction (left-right direction of FIG. 1 (A)) of a substantially rectangular parallelepiped shape, and 1st, 4th inclination end surface 613,624. Opposite, the second
The third inclined end surfaces 614 and 623 are joined in a state of facing each other.

The polarization separation / conversion layer 63 is sandwiched between first and second light incident surfaces 611 and 621 at 45 ° with respect to the first joint portion between the first inclined end surface 613 and the fourth inclined end surface 624. As shown in FIG. 1B, the polarization separation / conversion layer 63 includes a polarization separation film 631, and a half-wave plate 632 provided on the second light exit surface 622 side with respect to the polarization separation film 631. It has.
The polarization separation film 631 is made of Al ₂ O ₃ , SiO ₂ , MgF ₂ , and Subs made by Merck Co., Ltd.
It is a multilayer film made of tanceM2, and is formed on the first inclined end face 613. The polarization separation film 631 separates the incident light L into a P-polarized component and an S-polarized component, and transmits the P-polarized component.
The traveling direction is bent by 90 ° by reflecting the S-polarized light component.
The half-wave plate 632 is fixed between the polarization separation film 631 and the fourth inclined end surface 624. Examples of the method of fixing the half-wave plate 632 include a method of fixing with an acrylic photocurable adhesive and a method of fixing by a direct bonding method using a thin film of a silane coupling agent.
The half-wave plate 632 converts the P-polarized component transmitted through the polarization separation film 631 into an S-polarized component and transmits it, and emits it from the second light exit surface 622. The half-wave plate 632 is
The first crystal plate 633 provided on the polarization separation film 631 side and the second crystal plate 634 provided on the fourth inclined end surface 624 side are laminated. The first and second crystal plates 633
, 634 will be described later in detail.

As shown in FIG. 1A, the reflective film 65 is a dielectric multilayer film having a different refractive index.
First and second light incident surfaces 611 and 6 are formed at the second joint portion between the inclined end surface 614 and the third inclined end surface 623.
21 is sandwiched at an angle of 45 ° with respect to 21. The reflective film 65 is formed on the third inclined end surface 623, and is formed by, for example, the second inclined end surface 6 by the same fixing method as the half-wave plate 632.
14 is fixed. The reflection film 65 reflects the S-polarized light component reflected by the polarization separation film 631, bends the traveling direction by 90 °, and emits the light from the first light exit surface 612.

Next, the detailed configuration of the first and second crystal plates 633 and 634 will be described.
As shown in FIG. 2A, the first and second crystal plates 633 and 634 have plate thicknesses d1 and d2 of 21.
. It is formed in a plate shape of 2 μm to 50.0 μm and 13.5 μm to 31.9 μm. In the first and second crystal plates 633 and 634, the optical axes 633A and 634A exist along the plate surface.
It is formed from a cut quartz substrate. Here, as a method of forming the first and second quartz plates 633 and 634, the quartz plates cut from the quartz by Y-cut are polished so that the plate thicknesses d1 and d2 are in the above range. The method of doing can be illustrated.

The first and second crystal plates 633 and 634 are in a state where the P-polarized component of the incident light L is incident on the incident surfaces 633B and 634B at an incident angle of 45 °, and the first and second optical axis azimuths are 16.3 °
, 59.6 °, the second crystal plate 634 and the fourth inclined end surface 624 are provided. The azimuth angles of the first and second optical axes represent the azimuths of the optical axes 633A and 634A with respect to the vibration surfaces (horizontal vibration surfaces) 633C and 634C of the P-polarized light component in a counterclockwise direction from the vibration surfaces 633C and 634C. It is. As shown in FIG. 2B, the first and second crystal plates 633 and 634 are provided in such a state that the azimuth angles of the first and second optical axes are 16.3 ° and 59.6 °. In addition,
The angle formed by the projection optical axes 633F and 634F obtained by projecting the optical axes 633A and 634A onto the second light exit surface 622 from the incident direction of the P-polarized component and the vibration surfaces 633C and 634C, that is, the first of the projection optical axes 633F and 634F. , The second projection optical axis azimuth can be set to 22.5 ° and 67.5 °.

Here, it will be described with reference to FIG. 3 that the first crystal optical axis azimuth of the projection optical axis 633F can be made 22.5 ° by setting the first optical axis azimuth of the optical axis 633A to 16.3 °. To do.
In FIG. 3, the plane OAB represents the second light exit surface 622 of the second light transmissive substrate 62, and the plane OC
D represents the incident surface 633 </ b> B of the first crystal plate 633. Further, the plane OAB and the plane OCD have the same shape.
First, when the first crystal axis azimuth angle of the projection optical axis 633F is θa, the following formula (2) is established. Further, since the first crystal plate 633 is provided in a state inclined by 45 ° with respect to the second light emission surface 622, the expression (3) is established. Further, the first optical axis azimuth angle of the optical axis 633A is set to θa
Assuming that “a”, Expression (4) is established.

Further, when Expression (4) is substituted into Expression (3), Expression (5) is obtained. Further, since the lengths of CD and AB are equal, if this relationship is substituted into equation (2), equation (6) is obtained.

Substituting equation (6) into equation (5) yields equation (7). Further, when Expression (7) is expanded, Expressions (8) and (9) are obtained. The first crystal axis azimuth angle θa and the second crystal axis azimuth angle θb can be obtained from the equations (8) and (9).

Next, a method of minimizing the phase difference shift of the half-wave plate 632 using the Poincare sphere shown in FIG.
First, when the setting conditions are as follows, the polarization state of light transmitted through the first crystal plate 633 and the second crystal plate 634 can be considered as follows.
Incident polarization plane: horizontal direction in FIG. 4 First crystal plate: phase difference Γa = 180 °
: First crystal axis orientation angle = θa
Second crystal plate: phase difference Γb = 180 °
: Second crystal axis orientation angle = θb

The function of the half-wave plate 632 is to rotate the plane of polarization approximately 90 °, and this can be represented by a Poincare sphere from the position of coordinates P0 (S1, S2, S3) = (1, 0, 0). Coordinate P2
It is to move to (-1, 0, 0). Therefore, the start point is set as a coordinate P0 as an intersection of the S1 axis and the spherical surface. Next, the rotation axis R1 is set at a position where the S1 axis is rotated counterclockwise by 2θa. P0 is rotated clockwise by phase difference 180 ° with the R1 axis as the rotation axis, and the point reached is defined as P1. Next, the rotation axis R2 is set at a position obtained by rotating the S1 axis counterclockwise by 2θb. P1 is rotated in the clockwise direction by 180 degrees around the R2 axis as a rotation axis, and the point reached is defined as P2.

According to the above, in order for P2 to reach (−1, 0, 0), the first crystal axis orientation angle θa,
And the second crystal axis orientation angle θb only needs to satisfy the conditions of the following expressions (10) and (11). The phase difference α is set to ± 5 ° of the set value in consideration of the bonding accuracy.

FIG. 5 shows a view of the Poincare sphere of FIG. 4 viewed from the S3 axis. The rotation axis R1 when moving from the coordinate P0 to the coordinate P1 is at a position rotated by 2θa from the S1 axis. The rotation axis R2 when moving from the coordinate P1 to the coordinate P2 is at a position rotated by 2θb from the S1 axis.
Therefore, the center of the Poincare sphere is O, the angle formed by the coordinates P0, P1, and the center O is ∠P0-O-P1, and the angle formed by the coordinates P1, the coordinates P2, and the center O is ∠P1-O-. P
Assuming 2, the following equations (12) and (13) are obtained.

FIG. 6 shows a diagram linearly representing the phase difference when the polarized light moves from the coordinate P0 to the coordinate P2 on the equator plane of the Poincare sphere of FIG. The equator plane from the coordinate P0 through the coordinate P1 to P2 should be represented by a curve, but is represented by a straight line for easy understanding. rx is the coordinate P
This is the rotation radius when moving from 0 to the coordinate P1 with the R1 axis as the rotation axis. Further, rz is a rotation radius when moving from the coordinate P1 to the coordinate P2 using the R2 axis as a rotation axis. In the first crystal plate 633 processed so as to move from P0 to P1 with the radius of rotation r1 at the Poincare sphere, if the processing accuracy of the thickness of the crystal plate deviates from the design value, it cannot move to P1 but becomes P1x. In the second crystal plate 634 that is processed so as to move from P1 to P2 with the rotation radius rz, P
If 1 is processed to be P1z, P1−P1x = P1−P1z, and the half-wave plate 632 that can move to the position of P2 and has the function of an accurate half-wave plate can be provided.

When L = P1-P1x = P1-P1z, the following equations (14) and (15) are obtained.

  And from the formulas (14) and (15), the following formula (16) is obtained.

  Furthermore, if the radius of the Poincare sphere is k, the following equations (17) and (18) are obtained.

  From the equations (16), (17), and (18), the following equation (19) is obtained.

  From the equation (19), the shift amount ΔΓb is derived to the following equation (1).

In the half-wave plate in which a plurality of quartz plates are bonded in combination, quartz plates having the optimum phase difference ΔΓ can be combined with each other by using the equation (1). By selecting this equation (1), the phase difference as the half-wave plate 632 becomes the target value as described in the Poincare sphere, and the polarization conversion efficiency is the best.

Next, a method for optimizing the plate thicknesses d1 and d2 of the first and second crystal plates 633 and 634 will be described.
The thicknesses d1 and d2 of the first and second crystal plates 633 and 634 of the half-wave plate 632 having the optimum phase difference obtained from the equation (1) are expressed by the following equations (20), (21), And the Mueller determinant. Specifically, the incident angle of incident light is fixed to 45 °, and the first optical axis azimuth is set to 7.1 °, 10.7 °, 16.3 °, 22.2 °, and 26.3 °. First, when set
The plate thicknesses d1 and d2 of the second crystal plates 633 and 634 were obtained. FIG. 7 shows the result.

Next, the polarization conversion efficiency of the P-polarized component of the half-wave plate 632 to the S-polarized component will be described. The polarization conversion efficiency of the half-wave plate 632 was obtained based on the above formula (20), formula (21), Mueller determinant, and the like.

More specifically, the incident angle θ6 is + 10 ° (incident surface) with the light beam traveling angle θ5 as shown in FIG. 8 as 0 ° and the optical path of the incident light L incident at 45 ° as a reference (θ6 = 0 °). 5 in the range of the three-color wavelength band (400 nm to 700 nm).
The polarization conversion efficiency for each nm interval was obtained based on the above formulas (20) and (21). The light beam traveling angle θ5 is an angle between the projection surface M when the optical path of the incident light L incident at the incident angle θ6 is projected on the incident surface 633B and the vibration surface 633C of the P-polarized component from the vibration surface 633C. It is shown clockwise. That is, the light traveling angle θ5 of the P-polarized component is expressed as 0 °.
Further, the incident angle θ6 of the incident light L is set to + 8 ° while the ray traveling angle θ5 is fixed at 0 °.
, + 6 °, + 4 °, + 2 °, 0 °, −2 °, −4 °, −6 °, −8 °, and −10 °, the polarization conversion efficiencies of the three color wavelength bands were obtained. And what averaged the polarization conversion efficiency for every wavelength when incident angle (theta) 6 is -10 degrees-+10 degrees was calculated | required as an average polarization conversion efficiency with 0 degree of light advancing angles (theta) 5.
Then, the average polarization conversion efficiency with the light beam traveling angle θ5 of 0 ° was averaged over the entire three-color wavelength band to obtain the three-color polarization conversion efficiency of the half-wave plate 632.

Specifically, the first and second azimuth angles of the first and second optical axes are set to 16.3 ° and 59.6 °, respectively.
When the plate thicknesses d1 and d2 of the quartz plates 633 and 634 are set based on the relationship of FIG. 7 and the light beam traveling angle θ5 is set to 0 °, the three-color polarization conversion efficiency of the half-wave plate 632 is As shown in FIG.
From FIG. 9, it can be seen that when the plate thickness d1 of the first crystal plate 633 is 21.2 μm to 50.0 μm, the three-color conversion efficiency is 0.8 or more. From FIG. 7, the three-color conversion efficiency is 0.8.
It can be seen that the plate thickness d2 of the second crystal plate 634 for the above is 13.5 μm to 31.9 μm.
The plate thicknesses d1 and d2 of the first and second crystal plates 633 and 634 are lower limit values (21.2 μm,
13.5 μm) and upper limit values (50.0 μm, 31.9 μm), the trichromatic polarization conversion efficiency is
It became as follows.

The plate thicknesses d1 and d2 are lower limit values, the light beam traveling angle θ5 is 0 °, and the incident angle θ6 is −10 ° to +10.
The polarization conversion efficiency at ° was as shown in FIG.
Here, in the graph of FIG. 10, since there is no great difference in the polarization conversion efficiency at each incident angle θ6, only a few lines are drawn, but in reality, 11 lines are shown. It is drawn.
Further, the plate thicknesses d1 and d2 are lower limit values, the light beam traveling angle θ5 is 90 °, and the incident angle θ6 is −10.
FIG. 11 shows the polarization conversion efficiency when the angle is from .degree. To + 10.degree. Moreover, plate thickness d1, d
The polarization conversion efficiencies when 2 is the upper limit value, the light beam traveling angle θ5 is 0 °, + 90 °, and the incident angle θ6 is −10 ° to + 10 ° are as shown in FIGS.
And based on the relationship of FIGS. 10-13, plate | board thickness d1, d2 is a lower limit and 1/2 of an upper limit.
The three-color polarization conversion efficiency in the wave plate 632, that is, the average value in the portion surrounded by the three-color wavelength band region Aa as shown in FIGS. Further, when the plate thicknesses d1 and d2 are 12.5 μm and 7.9 μm which are smaller than the lower limit values, 69.6 μm and 44 which are larger than the upper limit values.
. The trichromatic polarization conversion efficiency in the case of 4 μm was determined. Further, plate thicknesses d1 and d2 that maximize the three-color polarization conversion efficiency were obtained. The results are shown in Table 1.

As shown in Table 1, it can be seen that the trichromatic polarization conversion efficiencies in the half-wave plate 632 with the plate thicknesses d1 and d2 being the lower limit value and the upper limit value are both 0.8 or more. Moreover, plate thickness d1, d
When 2 is smaller than the lower limit value or larger than the upper limit value, the trichromatic polarization conversion efficiency is 0
. It turns out that it is less than 8. That is, when the polarization conversion element 6 is installed in a state corresponding to incident light, the plate thicknesses d1 and d2 are 21.2 μm to 50.0 μm, 13.5 μm to 31.9 μm.
When the half-wave plate 632 composed of the m first and second crystal plates 633 and 634 is inclined by 45 ° with respect to the first light incident surface 611, the three colors of the half-wave plate 632 The polarization conversion efficiency is 0.8 or more.

Next, an example of a projector using the polarization conversion element 6 of the first embodiment will be described with reference to FIG.
The projector 1 includes an exterior housing 2, a projection lens 3 as a projection optical device, an optical unit 4, and the like.
The optical unit 4 includes a light source device 41, a uniform illumination optical device 42, a color separation optical device 43, a relay optical device 44, an optical device 45, and an optical component that houses and arranges these optical components 42 to 45 therein. And a housing 46.
The light source device 41 includes a light source lamp 411, a reflector 412, and a collimating lens 413. The radial light beam emitted from the light source lamp 411 is reflected by the reflector 412 and passes through the collimating lens 413. Ejected as parallel light.

The uniform illumination optical device 42 includes a first lens array 421, a second lens array 422, the above-described polarization conversion element 6, and a superimposing lens 424.
The first lens array 421 has a configuration in which first small lenses having a substantially rectangular outline when viewed from the incident optical axis direction are arranged in a matrix in a plane substantially orthogonal to the incident optical axis. . Each first small lens splits the light beam emitted from the light source device 41 into a plurality of partial light beams.
The second lens array 422 has substantially the same configuration as the first lens array 421, and has a configuration in which the second small lenses are arranged in a matrix. This second lens array 422
Has a function of forming an image of each first small lens of the first lens array 421 on a liquid crystal panel (to be described later) of the optical device 45 together with the superimposing lens 424.

In the polarization conversion element 6, the illumination optical axis in the design of the projector 1 and the first and second light incident surfaces 611 and 621 are orthogonal between the second lens array 422 and the superimposing lens 424, and the first 1
The first and second optical axis azimuth angles of the second crystal plates 633 and 634 are set to 16.3 ° and 59.6 °, respectively. Here, depending on the focal position of the second lens array 422 and the like, the light emitted from the second lens array 422 enters the first and second light incident surfaces 611 and 621 from −10 ° to +10.
Incident at an incident angle of °. That is, the polarization conversion element 6 is installed in a state corresponding to incident light.
The polarization conversion element 6 reflects and emits the S-polarized light component of the light of the three color wavelength bands from the second lens array 422 by the polarization separation film 631 and the reflection film 65 and transmits the P-polarized light transmitted through the polarization separation film 631. The component is converted into an S-polarized component by a half-wave plate 632 with a three-color polarization conversion efficiency of 0.8 or more and then emitted. That is, the polarization conversion element 6 converts the light into approximately one type of polarized light.
Specifically, each partial light converted into approximately one type of polarized light by the polarization conversion element 6 is finally superimposed on a liquid crystal panel (described later) of the optical device 45 by the superimposing lens 424. In a projector using a liquid crystal panel of a type that modulates polarized light, only one type of polarized light can be used, and therefore approximately half of the light from the light source device 41 that emits randomly polarized light cannot be used. For this reason, by using the polarization conversion element 6, the light emitted from the light source device 41 is converted into approximately one type of polarized light, and the light use efficiency in the optical device 45 is increased.

The color separation optical device 43 includes two dichroic mirrors 431 and 432 and a reflection mirror 4.
33, and has a function of separating a plurality of partial light beams emitted from the uniform illumination optical device 42 by the dichroic mirrors 431 and 432 into three color lights of red, green, and blue.
The relay optical device 44 includes an incident side lens 441, a relay lens 443, and a reflection mirror 4.
42 and 444, and has a function of guiding the red light separated by the color separation optical device 43 to a later-described red light liquid crystal panel of the optical device 45.

At this time, in the dichroic mirror 431 of the color separation optical device 43, the uniform illumination optical device 4.
The blue light component of the light beam emitted from 2 is reflected, and the red light component and the green light component are transmitted. The blue light reflected by the dichroic mirror 431 is reflected by the reflection mirror 433, passes through the field lens 425, and reaches a later-described blue light liquid crystal panel of the optical device 45.
The field lens 425 converts each partial light beam emitted from the second lens array 422 into a light beam parallel to the central axis (principal ray). The same applies to the field lens 425 provided on the light beam incident side of the other liquid crystal panel for green light and red light.

Of the red light and green light transmitted through the dichroic mirror 431, the green light is reflected by the dichroic mirror 432, passes through the field lens 425, and reaches a later-described green light liquid crystal panel of the optical device 45. On the other hand, the red light passes through the dichroic mirror 432, passes through the relay optical device 44, passes through the field lens 425, and reaches a later-described red light liquid crystal panel of the optical device 45.

The optical device 45 includes three liquid crystal panels 451 as light modulators (the liquid crystal panel for red light is 451R, the liquid crystal panel for green light is 451G, and the liquid crystal panel for blue light is 451B), and these liquid crystals A polarizing element 5 and a cross dichroic prism 454 are provided on the light incident side and the light emitting side of the panel 451, respectively.

The polarizing element 5 is disposed on the light incident side of each liquid crystal panel 451, respectively.
A and an exit-side polarizing plate 5B disposed on the light-emission side of each liquid crystal panel 451.
The incident-side polarizing plate 5 </ b> A includes the polarization conversion element 6 among the color lights separated by the color separation optical device 43.
Only the polarized light having a polarization direction substantially the same as the polarization direction aligned in (1) is transmitted, and other light beams are absorbed.
The liquid crystal panel 451 modulates the polarization direction of the polarized light beam emitted from the incident-side polarizing plate 5A.
The exit-side polarizing plate 5B has substantially the same configuration as the incident-side polarizing plate 5A. Of the light beams emitted from the image forming area of the liquid crystal panel 451, the polarized light orthogonal to the transmission axis of the light beam in the incident-side polarizing plate 5A. Only a light beam having a direction is transmitted, and other light beams are absorbed.

The cross dichroic prism 454 forms a color image by synthesizing the optical image modulated for each color light emitted from the emission side polarizing plate 5B. This cross dichroic prism 4
The color image formed at 54 is enlarged and projected onto the screen or the like by the projection lens 3 described above.

Therefore, in the first embodiment, the following operational effects can be achieved.
The plate thicknesses d1 and d2 of the first and second crystal plates 633 and 634 constituting the half-wave plate 632 of the polarization conversion element 6 are set to 21.2 μm to 50.0 μm and 13.5 μm to 31.9 μm, respectively. Therefore, the three-color polarization conversion efficiency at the half-wave plate 632 when the polarization conversion element 6 is installed in a state corresponding to incident light can be 0.8 or more. Therefore, even when the polarization conversion element 6 is installed on the light exit side of the second lens array 422 in the projector 1, that is, −10 ° to +
Even when incident light is incident at an incident angle of 10 °, incident light in the three-color wavelength band is converted into polarized light with a three-color polarization conversion efficiency of 0.8 or more by the half-wave plate 632. Therefore, the polarization conversion element 6 having practicality can be provided. Furthermore, since the half-wave plate 632 includes the first and second crystal plates 633 and 634 having the performance based on the above formula (1), the polarization conversion element 6 having high polarization conversion efficiency can be provided.
Further, when the polarization conversion element 6 is used in the projector 1, a blue component having no practical problem,
A reproducible green component and a red component can be projected, and an image having brightness with no problem can be projected.

Next, 2nd Embodiment of this invention is described based on drawing. In the second embodiment, a polarization conversion element having a half-wave plate with a blue polarization conversion efficiency of 0.8 or more will be described.
As shown in FIGS. 1 and 2, the half-wave plate 636 constituting the polarization conversion element 6A is based on a Y-cut quartz substrate and has plate thicknesses d11 and d12 of 16.8 μm to 43.7 μm, 10. 7μ
The first and second crystal plates 637 and 638 are formed in a plate shape of m to 27.8 μm. The half-wave plate 636 is in a state in which the P-polarized component of the incident light L is incident on the incident surface 633B at an incident angle of 45 °, and the first and second quartz plates 637 and 638 are first and first. Two optical axis azimuth angles are provided in a state of 16.3 ° and 59.6 °. The half-wave plate 636 is
It consists of first and second quartz plates 637 and 638 having performance based on the above formula (1).

Then, by the same method as the half-wave plate 632 of the first embodiment, the blue wavelength band (400 nm to 400 nm) when the light beam traveling angle θ5 is 0 ° and the incident angle θ6 of the incident light L is −10 ° to + 10 °.
The average polarization conversion efficiency at 500 nm) was obtained and averaged over the entire blue wavelength band was obtained as the blue polarization conversion efficiency of the half-wave plate 636.

Specifically, the first and second azimuth angles of the first and second optical axes are set to 16.3 ° and 59.6 °, respectively.
The blue polarization conversion efficiency of the half-wave plate 636 when the plate thicknesses d11 and d12 of the quartz plates 637 and 638 are set based on the relationship of FIG. 7 and the light beam traveling angle θ5 is set to 0 ° is shown in FIG. It came to show in 9.
From FIG. 9 and FIG. 7, the plate thicknesses d11 and d12 of the first and second crystal plates 637 and 638 are 1.
In the case of 6.8 μm to 43.7 μm and 10.7 μm to 27.8 μm, the blue conversion efficiency is 0.8.
It turns out that it becomes the above.
The plate thicknesses d11 and d12 of the first and second crystal plates 637 and 638 are lower limit values (16.8 μm).
m, 10.7 μm) and upper limit values (43.7 μm, 27.8 μm), the blue polarization conversion efficiency was as follows.

When the plate thicknesses d11 and d12 are the lower limit values, the polarization conversion efficiencies when the light beam traveling angle θ5 is −0 ° and + 90 ° are as shown in FIGS. Further, when the plate thicknesses d11 and d12 are the upper limit values, the polarization conversion efficiencies when the light beam traveling angle θ5 is 0 ° and + 90 ° are shown in FIGS.
It came to show in.
Then, the average of the polarization conversion efficiencies of the portions surrounded by the blue wavelength band region Ab as shown in FIGS. 15 to 18 is the blue color in the half-wave plate 636 in which the plate thicknesses d11 and d12 are the lower limit value and the upper limit value. The polarization conversion efficiency was obtained. Further, the plate thicknesses d11 and d12 are 12.5 μm and 7.9 μm.
In the case of m, the blue polarization conversion efficiency in each of the cases of 69.6 μm and 44.4 μm was obtained. Further, plate thicknesses d11 and d12 that maximize the blue polarization conversion efficiency were obtained. The results are shown in Table 2.

As shown in Table 2, it can be seen that the blue polarization conversion efficiencies of the half-wave plates 636 with the plate thicknesses d11 and d12 being the lower limit value and the upper limit value are both 0.8 or more. Also, the plate thickness d1
1, d12 is smaller than the lower limit value, if larger than the upper limit value, the blue polarization conversion efficiency is
It turns out that it is less than 0.8. That is, by installing the polarization conversion element 6A in a state corresponding to incident light, the plate thicknesses d11 and d12 are 16.8 μm to 43.7 μm and 10.7 μm to 2 respectively.
A half-wave plate 636 composed of 7.8 μm first and second crystal plates 637 and 638 is the first.
In a state where the light incident surface 611 is inclined by 45 °, the blue polarization conversion efficiency of the half-wave plate 636 is 0.8 or more.

The polarization conversion element 6A according to the second embodiment emits light of only a blue wavelength band, and emits light of only a green wavelength band, for example, instead of the light source device 41 of the projector 1 as shown in FIG. The present invention can be applied to a green light source device that emits light and a red light source device that emits light only in the red wavelength band (hereinafter referred to as an RGB light source projector). Specifically, the polarization conversion element 6A includes an illumination optical axis in the design of the blue light source device of the RGB light source projector,
The first and second light incident surfaces 611 and 621 are orthogonal to each other, and the first and second crystal plates 637 and 638 are used.
The first and second optical axis azimuth angles are set to 16.3 ° and 59.6 °, that is, in a state corresponding to incident light.
Further, in the projector 1 in which the polarization conversion element 6 is not provided in the configuration as shown in FIG. 14, the polarization conversion element 6A is in the optical path between the dichroic mirror 431 and the incident side polarizing plate 5A. Installed in a state corresponding to incident light.
This polarization conversion element 6A converts incident light in the blue wavelength band into an S-polarized component with a blue polarization conversion efficiency of 0.8 or more and emits it.

Therefore, in the second embodiment, the following operational effects can be achieved.
The plate thicknesses d11 and d12 of the first and second crystal plates 637 and 638 constituting the half-wave plate 636 of the polarization conversion element 6A are set to 16.8 μm to 43.7 μm and 10.7 μm to 27.8 μm, respectively. Therefore, the half-wave plate 636 when the polarization conversion element 6A is installed in a state corresponding to incident light.
The polarization conversion element 6A having blue light conversion efficiency at 0.8 can be made 0.8 or more and has practicality
Can provide. Further, the half-wave plate 636 has the first performance having the performance based on the above formula (1).
Since the second crystal plates 637 and 638 are used, the polarization conversion element 6A having high polarization conversion efficiency can be provided.
Further, when the polarization conversion element 6A is used for an RGB light source projector, it is possible to project an image having a reproducibility of a blue component that has no practical problem and brightness with no problem.

Next, 3rd Embodiment of this invention is described based on drawing. In the third embodiment, a polarization conversion element having a half-wave plate with a green polarization conversion efficiency of 0.8 or more will be described.
As shown in FIGS. 1 and 2, the half-wave plate 640 constituting the polarization conversion element 6B is based on a Y-cut quartz substrate and has thicknesses d21 and d22 of 21.0 μm to 55.6 μm, 13. 4μ
The first and second crystal plates 641 and 642 are formed in a plate shape of m to 35.4 μm. The half-wave plate 640 is in a state in which the P-polarized component of the incident light L is incident on the incident surface 633B at an incident angle of 45 °, and the first and second crystal plates 641 and 642 are first and first. Two optical axis azimuth angles are provided in a state of 16.3 ° and 59.6 °. The half-wave plate 640 is
It consists of first and second crystal plates 641 and 642 having performance based on the above formula (1).

Then, by the same method as that of the half-wave plate 632 of the first embodiment, the green wavelength band (500 nm to when the light traveling angle θ5 is 0 ° and the incident angle θ6 of the incident light L is −10 ° to + 10 ° is used.
The average polarization conversion efficiency at 600 nm) was obtained and averaged over the entire green wavelength band was obtained as the green polarization conversion efficiency of the half-wave plate 640.

Specifically, the first and second azimuth angles of the first and second optical axes are set to 16.3 ° and 59.6 °, respectively.
The green polarization conversion efficiency of the half-wave plate 640 when the plate thicknesses d21 and d22 of the quartz plates 641 and 642 are set based on the relationship of FIG. 7 and the light beam traveling angle θ5 is set to 0 ° is shown in FIG. It came to show in 9.
9 and 7, the thicknesses d21 and d22 of the first and second crystal plates 641 and 642 are 2 respectively.
In the case of 1.0 μm to 55.6 μm and 13.4 μm to 35.4 μm, the green conversion efficiency is 0.8.
It turns out that it becomes the above.
The plate thicknesses d21 and d22 of the first and second crystal plates 641 and 642 are lower limit values (16.8 μm).
m, 10.7 μm) and upper limit values (43.7 μm, 27.8 μm), the green polarization conversion efficiency was as follows.

When the plate thicknesses d21 and d22 are the lower limit values, the polarization conversion efficiencies when the light beam traveling angle θ5 is −0 ° and + 90 ° are as shown in FIGS. Furthermore, when the plate thicknesses d21 and d22 are the upper limit values, the polarization conversion efficiencies when the light beam traveling angle θ5 is 0 ° and + 90 ° are shown in FIGS.
It came to show in.
Then, the average of the polarization conversion efficiencies of the portions surrounded by the green wavelength band region Ag as shown in FIGS. 19 to 22 is the green color in the half-wave plate 640 with the plate thicknesses d21 and d22 being the lower limit value and the upper limit value. The polarization conversion efficiency was obtained. The plate thicknesses d21 and d22 are 12.5 μm and 7.9 μm.
In the case of m, green polarization conversion efficiencies in the cases of 69.6 μm and 44.4 μm were obtained. Further, plate thicknesses d21 and d22 that maximize the green polarization conversion efficiency were obtained. The results are shown in Table 3.

As shown in Table 3, it can be seen that the green polarization conversion efficiencies of the half-wave plates 640 with the plate thicknesses d21 and d22 being the lower limit value and the upper limit value are both 0.8 or more. Also, the plate thickness d2
1, d22 is smaller than the lower limit value, if larger than the upper limit value, the green polarization conversion efficiency is
It turns out that it is less than 0.8. That is, when the polarization conversion element 6B is installed in a state corresponding to incident light, the plate thicknesses d21 and d22 are 21.0 μm to 55.6 μm, 13.4 μm to 3
A half-wave plate 640 composed of 5.4 μm first and second crystal plates 641 and 642 is the first.
When the state is inclined by 45 ° with respect to the light incident surface 611, the green polarization conversion efficiency of the half-wave plate 640 is 0.8 or more.

For example, the polarization conversion element 6B of the third embodiment is installed on the illumination optical axis in the design of the green light source device of the RGB light source projector in a state corresponding to the incident light described above.
Further, in the projector 1 in which the polarization conversion element 6 is not provided in the configuration as illustrated in FIG. 14, the polarization conversion element 6B is included in the optical path between the dichroic mirror 432 and the incident-side polarizing plate 5A. Installed in a state corresponding to incident light.
This polarization conversion element 6B converts the incident light in the green wavelength band into an S-polarized component with a green polarization conversion efficiency of 0.8 or more and emits it.

Therefore, in the third embodiment, the following operational effects can be achieved.
The plate thicknesses d21 and d22 of the first and second crystal plates 641 and 642 constituting the half-wave plate 640 of the polarization conversion element 6B are set to 21.0 μm to 55.6 μm and 13.4 μm to 35.4 μm, respectively. Therefore, the half-wave plate 640 when the polarization conversion element 6B is installed in a state corresponding to incident light.
The polarization conversion element 6B has a practicality that can make the green polarization conversion efficiency at 0.8 or more.
Can provide. Furthermore, the half-wave plate 640 has the first performance having the performance based on the above formula (1).
Since the second crystal plates 641 and 642 are used, the polarization conversion element 6B having high polarization conversion efficiency can be provided.
Further, when the polarization conversion element 6B is used in the projector 1, it is possible to project an image having a reproducibility of a green component that has no practical problem and brightness with no problem.

Next, 4th Embodiment of this invention is described based on drawing. In the fourth embodiment, a polarization conversion element having a half-wave plate with a red polarization conversion efficiency of 0.8 or more will be described.
As shown in FIGS. 1 and 2, the half-wave plate 644 constituting the polarization conversion element 6C is based on a Y-cut quartz substrate and has plate thicknesses d31 and d32 of 25.3 μm to 67.2 μm, 16. 1μ
The first and second crystal plates 645 and 646 are formed in a plate shape of m to 42.8 μm. The half-wave plate 644 is in a state in which the P-polarized component of the incident light L is incident on the incident surface 633B at an incident angle of 45 °, and the first and second quartz plates 645 and 646 are first and first. Two optical axis azimuth angles are provided in a state of 16.3 ° and 59.6 °. The half-wave plate 644 is
The first and second quartz plates 645 and 646 having performance based on the above formula (1) are included.

Then, by the same method as the half-wave plate 632 of the first embodiment, the red wavelength band (600 nm to 600 nm) when the light beam traveling angle θ5 is 0 ° and the incident angle θ6 of the incident light L is −10 ° to + 10 °.
The average polarization conversion efficiency at 700 nm) was obtained, and the average polarization conversion efficiency over the entire red wavelength band was obtained as the red polarization conversion efficiency of the half-wave plate 644.

Specifically, the first and second azimuth angles of the first and second optical axes are set to 16.3 ° and 59.6 °, respectively.
The red polarization conversion efficiency of the half-wave plate 644 when the plate thicknesses d31 and d32 of the quartz plates 645 and 646 are set based on the relationship of FIG. 7 and the light beam traveling angle θ5 is set to 0 ° is shown in FIG. It came to show in 9.
9 and 7, the thicknesses d31 and d32 of the first and second crystal plates 645 and 646 are 2 respectively.
In the case of 5.3 μm to 67.2 μm and 16.1 μm to 42.8 μm, the red conversion efficiency is 0.8.
It turns out that it becomes the above.
The plate thicknesses d31 and d32 of the first and second crystal plates 645 and 646 are lower limit values (25.3 μm).
m, 16.1 μm) and upper limit values (67.2 μm, 42.8 μm), the red polarization conversion efficiency was as follows.

When the plate thicknesses d31 and d32 are the lower limit values, the polarization conversion efficiencies when the light beam traveling angle θ5 is −0 ° and + 90 ° are as shown in FIGS. Further, when the plate thicknesses d31 and d32 are the upper limit values, the polarization conversion efficiencies when the light beam traveling angle θ5 is 0 ° and + 90 ° are shown in FIGS.
It came to show in.
The average of the polarization conversion efficiencies of the portions surrounded by the red wavelength band region Ar as shown in FIGS. 23 to 26 is the red color in the half-wave plate 644 whose plate thicknesses d31 and d32 are the lower limit value and the upper limit value. The polarization conversion efficiency was obtained. Further, the plate thicknesses d31 and d32 are 25.3 μm to 67.2.
In the case of μm, the red polarization conversion efficiency in each of the case of 16.1 μm to 42.8 μm was obtained. Further, plate thicknesses d31 and d32 that maximize the red polarization conversion efficiency were obtained. The results are shown in Table 4.

As shown in Table 4, it can be seen that the red polarization conversion efficiencies of the half-wave plates 644 whose plate thicknesses d31 and d32 are the lower limit value and the upper limit value are both 0.8 or more. Also, the plate thickness d3
1, when d32 is smaller than the lower limit value and larger than the upper limit value, the red polarization conversion efficiency is
It turns out that it is less than 0.8. That is, when the polarization conversion element 6C is installed in a state corresponding to incident light, the plate thicknesses d31 and d32 are 25.3 μm to 67.2 μm and 16.1 μm to 4 respectively.
A half-wave plate 644 made up of 2.8 μm first and second crystal plates 645 and 646 is the first.
When the state is inclined by 45 ° with respect to the light incident surface 611, the red polarization conversion efficiency of the half-wave plate 644 is 0.8 or more.

The polarization conversion element 6C of the fourth embodiment is installed on the illumination optical axis in the design of the red light source device of the RGB light source projector, for example, in a state corresponding to the incident light described above.
Further, in the projector 1 in which the polarization conversion element 6 is not provided in the configuration as illustrated in FIG. 14, the polarization conversion element 6C is included in the optical path between the reflection mirror 442 and the incident-side polarizing plate 5A. Installed in a state corresponding to incident light.
The polarization conversion element 6C converts incident light in the red wavelength band into an S-polarized component with a red polarization conversion efficiency of 0.8 or more and emits it.

Therefore, in the fourth embodiment, the following operational effects can be achieved.
The plate thicknesses d31 and d32 of the first and second crystal plates 645 and 646 constituting the half-wave plate 644 of the polarization conversion element 6C are set to 25.3 μm to 67.2 μm and 16.1 μm to 42.8 μm, respectively. Therefore, the half-wave plate 644 when the polarization conversion element 6C is installed in a state corresponding to incident light.
The polarization conversion efficiency of the polarization conversion element 6C can be made 0.8 or more and has practicality
Can provide. Further, the half-wave plate 644 has the first performance having the performance based on the above formula (1).
Since it comprises the second crystal plates 645 and 646, the polarization conversion element 6C having high polarization conversion efficiency can be provided.
Further, when the polarization conversion element 6C is used in the projector 1, it is possible to project an image having a reproducibility of a red component that has no practical problem and brightness with no problem.

For example, in the case of white light, the projector light source has a luminance distribution according to the wavelength band. However, there are cases where it is desired to brighten some wavelength bands against the above luminance, depending on the visibility of the human observing the projector. A projector using projection light synthesized from monochromatic wavelength band light sources of R light (red light), G light (green light), and B light (blue light) has also been proposed.
If the polarization conversion element of this application is used for these projectors, the polarization efficiency in the wavelength band can be optimized, and polarized light in a specific wavelength band can be obtained strongly, so that the person observing observes an image with a desired hue. it can.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, as the application of the polarization conversion elements 6, 6 </ b> A, 6 </ b> B, and 6 </ b> C, the configuration used for the projector is illustrated, but the configuration is not limited to this, and may be used for devices other than the projector.

  The present invention can be used for polarization conversion elements used in projectors and other devices.

It is a schematic diagram which shows the structure of the polarization conversion element concerning the 1st-4th embodiment of this invention, (A) is sectional drawing, (B) is sectional drawing to which Q part of (A) was expanded. It is a schematic diagram which shows the principal part of the polarization conversion element concerning the said 1st-4th embodiment, (A) shows the optical axis azimuth of a 1/2 wavelength plate, (B) shows the projection optical axis azimuth. Show. Explanatory drawing which shows the relationship between the optical axis azimuth according to the first embodiment and the projection optical axis azimuth. The perspective view which shows the Poincare sphere for demonstrating the half-wave plate concerning the said 1st Embodiment. The top view which shows the Poincare sphere concerning the said 1st Embodiment from S3 axial direction. The figure which showed on the straight line the polarization | polarized-light of the equatorial plane of the Poincare sphere concerning the said 1st Embodiment. The graph which shows the relationship of the board thickness of the optimized 1st, 2nd crystal plate concerning the said 1st-4th embodiment. Explanatory drawing explaining the light ray advance angle and incident angle of the incident light concerning the said 1st Embodiment. The graph which shows the relationship between the plate | board thickness of the 1st crystal plate concerning the said 1st-4th embodiment, and polarization conversion efficiency. Polarization conversion efficiency when the thickness of the first and second quartz plates constituting the half-wave plate for the three-color wavelength band according to the first embodiment is the lower limit value and the light beam traveling angle is 0 ° Graph showing. Polarization conversion efficiency when the thickness of the first and second crystal plates constituting the half-wave plate for the three-color wavelength band according to the first embodiment is the lower limit value and the light beam traveling angle is + 90 ° Graph showing. Polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for the three-color wavelength band according to the first embodiment is the upper limit and the light beam traveling angle is 0 ° Graph showing. Polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for the three-color wavelength band according to the first embodiment is the upper limit value and the light beam traveling angle is + 90 ° Graph showing. The conceptual diagram which shows the projector concerning the said 1st Embodiment. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for blue wavelength band according to the second embodiment is the lower limit value and the light beam traveling angle is 0 °. Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for blue wavelength band according to the second embodiment is the lower limit value and the light beam traveling angle is + 90 °. Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for blue wavelength band according to the second embodiment is the upper limit value and the light beam traveling angle is 0 ° Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for blue wavelength band according to the second embodiment is the upper limit value and the light ray traveling angle is + 90 ° Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for green wavelength band according to the third embodiment is the lower limit value and the light beam traveling angle is 0 °. Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for the green wavelength band according to the third embodiment is the lower limit value and the light beam traveling angle is + 90 °. Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for green wavelength band according to the third embodiment is the upper limit value and the light beam traveling angle is 0 °. Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for green wavelength band according to the third embodiment is the upper limit value and the light ray traveling angle is + 90 °. Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for the red wavelength band according to the fourth embodiment is the lower limit and the light beam traveling angle is 0 °. Graph showing. The polarization conversion efficiency when the plate thickness of the first and second crystal plates constituting the half-wave plate for red wavelength band according to the fourth embodiment is the lower limit value and the light ray traveling angle is + 90 °. Graph showing. The polarization conversion efficiency when the plate thickness of the first and second quartz plates constituting the half-wave plate for red wavelength band according to the fourth embodiment is the upper limit value and the light beam traveling angle is 0 °. Graph showing. The polarization conversion efficiency when the thickness of the first and second crystal plates constituting the half-wave plate for the red wavelength band according to the fourth embodiment is the upper limit value and the light ray traveling angle is + 90 ° Graph showing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Projector, 3 ... Projection lens as projection optical apparatus, 6, 6A, 6B, 6C ... Polarization conversion element, 41 ... Light source device, 61, 62 ... 1st, 2nd translucent base material, 63 ... Polarization separation conversion Layer 65, reflective film, 451, liquid crystal panel as light modulator, 611, 621, first and second
Light incident surface, 631... Polarization separation film, 632, 636, 640, 644.
3, 637, 641, 645 ... first crystal plate, 634, 638, 642, 646 ... second crystal plate, L ... incident light

Claims (10)

A first retardation plate having a phase difference Γ′a and a second retardation plate having a phase difference Γ′b with respect to light having a wavelength λ incident from a direction of 45 ° with respect to the normal line of the incident surface are respectively optically coupled. The polarization plane of linearly polarized light incident from the direction of 45 ° with respect to the normal of the incident plane in the range of wavelengths λ1 to λ2 (where λ1 <λ <λ2) is 90 deg. It is a laminated phase difference plate that converts to a linearly polarized light that is rotated and emits it,
An angle formed by a projection vibration surface obtained by projecting the vibration surface of linearly polarized light incident on the first retardation plate onto the incident surface and the first crystal optical axis of the first retardation plate is defined as a first optical axis azimuth angle θaa. ,
An angle formed by the projection vibration surface and the second crystal optical axis of the second retardation plate is a second optical axis azimuth angle θbb,
The angle formed between the first projected crystal optical axis obtained by projecting the first crystal optical axis on a plane perpendicular to the optical axis of the incident linearly polarized light and the vibrating surface of the incident linearly polarized light is the first projected optical axis azimuth angle θa. age,
When the angle formed between the second projected crystal optical axis obtained by projecting the second crystal optical axis on the vertical plane and the incident plane of the linearly polarized light is the second projected optical axis azimuth θb,
The relationship between the first optical axis azimuth angle θaa and the first projection optical axis azimuth angle θa is:
θaa = Atan (tan (θa) / 2 ^1/2 )
Satisfied,
The relationship between the second optical axis azimuth angle θbb and the second projection optical axis azimuth angle θb is
θbb = Atan (tan (θb) / 2 ^1/2 )
Satisfied,
The angle formed between the projection image when the optical axis of the incident linearly polarized light is projected onto the incident surface and the projection vibration surface is a light beam traveling angle θ5,
The angle formed between the direction of 45 ° with respect to the normal of the incident surface and the optical axis of the incident linearly polarized light is defined as an incident angle θ6.
The ray traveling angle θ5 and the incident angle θ6 are:
θ5 = 0 °,
−10 ° ≦ θ6 ≦ + 10 °
Satisfied,
When the relationship between the first projection optical axis azimuth angle θa and the second projection optical axis azimuth angle θb is set to α,
θb = θa + α
40 ° <α <50 °
Satisfy the conditions of
The phase difference Γ′a and the phase difference Γ′b are set as ΔΓa as a deviation amount from the design target value of the phase difference Γa of the first crystal plate, and from the design target value of the phase difference Γb of the second crystal plate. If the amount of deviation is ΔΓb,
Γ′a = Γa + ΔΓa,
Γ′b = Γb + ΔΓb,
Γa = 180 °,
Γb = 180 °
Satisfied,
A laminated phase difference plate, wherein the relationship between ΔΓa and ΔΓb satisfies the formula (1).

In the laminated phase difference plate according to claim 1,
The material of the first and second retardation plates is quartz,
The laminated phase difference plate, wherein the first and second crystal optical axes are parallel to the incident surface . In the laminated phase difference plate according to claim 2,
When λ1 = 400 nm and λ2 = 700 nm,
A thickness d1 of the first retardation plate is in a range of 21.2 μm to 50.0 μm;
A laminated retardation plate, wherein the thickness d2 of the second retardation plate is in the range of 13.5 μm to 31.9 μm . In the laminated phase difference plate according to claim 2,
When λ1 = 400 nm and λ2 = 500 nm,
The thickness d1 of the first retardation plate is in the range of 16.8 μm to 43.7 μm,
A laminated retardation plate, wherein the thickness d2 of the second retardation plate is in the range of 10.7 μm to 27.8 μm . In the laminated phase difference plate according to claim 2,
When λ1 = 500 nm and λ2 = 600 nm,
A thickness d1 of the first retardation plate is in a range of 21.0 μm to 55.6 μm;
The laminated retardation plate, wherein a thickness d2 of the second retardation plate is in a range of 13.4 μm to 35.4 μm . In the laminated phase difference plate according to claim 2,
When λ1 = 600 nm and λ2 = 700 nm,
A thickness d1 of the first retardation plate is in a range of 25.3 μm to 67.2 μm;
The laminated phase difference plate, wherein a thickness d2 of the second phase difference plate is in a range of 16.1 μm to 42.8 μm . A plate-like laminated prism having a first main surface as a light incident surface and a second main surface as a light output surface;
A polarization separation / conversion layer and a reflective portion alternately arranged in parallel at an interval of 45 ° with respect to the first and second main surfaces;
The polarization separation conversion layer is composed of a polarization separation unit disposed in order from the first main surface side and a wave plate provided on the light exit surface side of the polarization separation unit,
The polarization separation unit separates light incident from the first main surface side into first linearly polarized light and second linearly polarized light that are orthogonal to each other, transmits the first linearly polarized light, and transmits the second linearly polarized light. Reflects the linearly polarized light of
The wave plate is converted into linearly polarized light having a vibration surface parallel to the vibration surface of the second linearly polarized light by rotating the vibration surface of the first linearly polarized light transmitted through the polarization separating unit by 90 °. Let out,
The polarization plate according to claim 1, wherein the wave plate is the laminated phase difference plate according to claim 1 . A light source;
A polarization conversion element that converts the light from the light source into the second linearly polarized light and emits it;
Modulation means for modulating the light emitted from the polarization conversion element according to image information;
A projection optical system that projects the light modulated by the modulation means;
Have
The projection type image apparatus, wherein the polarization conversion element is the polarization conversion element according to claim 7 . In the projection type video device according to claim 8,
A projection type video apparatus, wherein the modulation means is a liquid crystal panel . A light source;
A polarization conversion element that converts the light from the light source into the second linearly polarized light and emits it;
Modulation means for modulating the light emitted from the polarization conversion element according to image information;
A projection optical system that projects the light modulated by the modulation means;
A projection type video apparatus comprising:
A projection type video apparatus comprising the laminated phase difference plate according to any one of claims 1 to 6 .

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