Polarization beam splitting element and image projection apparatus
AssigneeCanon Kabushiki Kaisha
InventorRie ISHIMATSU
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Abstract
The polarization beam splitting element is configured to reflect or transmit an entering beam according to its polarization direction. The element includes, in order from a beam entrance side, a base member having a light transmissive property, a first one-dimensional grating structure formed of a dielectric material and having, in a first direction, a first grating period smaller than a wavelength of the entering beam, and a second one-dimensional grating structure formed of a metal and having, in a second direction orthogonal to the first direction, a second grating period smaller than the wavelength of the entering beam.
Claims11
A polarization beam splitting element configured to reflect or transmit an entering beam according to its polarization direction, the element comprising in order from a beam entrance side:
- a base member having a light transmissive property;
- a first one-dimensional grating structure formed of a dielectric material and having, in a first direction, a first grating period smaller than a wavelength of the entering beam;
- and
- a second one-dimensional grating structure formed of a metal and having, in a second direction orthogonal to the first direction, a second grating period smaller than the wavelength of the entering beam.
An image projection apparatus comprising:
- a polarization beam splitting element configured to reflect or transmit light as a entering beam from a light source according to its polarization direction;
- a light modulation element configured to modulate the light from the polarization beam splitting element;
- and
- a projection optical system configured to project the light introduced from the light modulation element through the polarization beam splitting element onto a projection surface,
- wherein the polarization beam splitting element comprises in order from a beam entrance side:
- a base member having a light transmissive property;
- a first one-dimensional grating structure formed of a dielectric material and having, in a first direction, a first grating period smaller than a wavelength of the entering beam;
- and
- a second one-dimensional grating structure formed of a metal and having, in a second direction orthogonal to the first direction, a second grating period smaller than the wavelength of the entering beam.
An image projection apparatus comprising:
- a color separation optical system configured to separate light from a light source into plural color lights;
- plural light modulation elements configured to respectively modulate the color lights;
- and
- a projection optical system configured to project the color lights from the light modulation elements onto a projection surface,
- wherein the color separation optical system includes a polarization beam splitting element configured to reflect or transmit the light as an entering beam from the light source according to its polarization direction, the polarization beam splitting element comprising in order from a beam entrance side:
- a base member having a light transmissive property;
- a first one-dimensional grating structure formed of a dielectric material and having, in a first direction, a first grating period smaller than a wavelength of the entering beam;
- and
- a second one-dimensional grating structure formed of a metal and having, in a second direction orthogonal to the first direction, a second grating period smaller than the wavelength of the entering beam.
Dependencies are inferred from the claim text.