Imaging apparatus and optical low-pass filter
AssigneeCanon Kabushiki Kaisha
InventorsYutaka Yamaguchi, Kazuhiko Momoki
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Abstract
An imaging apparatus includes an optical low-pass filter that includes first, second, third, and fourth optical anisotropic elements configured to separate an incident ray into a plurality of rays, and a retardation plate disposed between two optical anisotropic elements adjacent to each other among the first to fourth optical anisotropic elements, and an image sensor configured to photoelectrically convert an optical image formed by light that has passed the optical low-pass filter. A predetermined condition is satisfied.
Claims22
An imaging apparatus comprising:
- an optical low-pass filter that includes first, second, third, and fourth optical anisotropic elements each configured to separate an incident ray into a plurality of rays, and a retardation plate disposed between two optical anisotropic elements adjacent to each other among the first to fourth optical anisotropic elements;
- and
- an image sensor configured to photoelectrically convert an optical image formed by light that has passed the optical low-pass filter,
- wherein the following condition is satisfied:
- −0.20≤I≤0.20
- I
- =
- ∫
- λ
- max
- λ
- min
-
- s
-
- (
- λ
- )
- ·
- cos
-
- (
- 2
-
- π
- /
- λ
- ·
- δ
-
- (
- λ
- )
- )
-
- d
-
-
- λ
- where λ is a wavelength of the light, δ(λ) is a phase difference of the retardation plate, S(λ) is a normalized spectral sensitivity spectrum of the image sensor, and λmax and λmin are the longest wavelength and the shortest wavelength in an integration range that is 10% or more of a peak intensity of the S(λ), respectively.
An optical low-pass filter used for an imaging apparatus that includes an image sensor, the optical low-pass filter comprising:
- first, second, third, and fourth optical anisotropic elements each configured to separate incident ray into a plurality of rays;
- and
- a retardation plate disposed between two optical anisotropic elements adjacent to each other among the first to fourth optical anisotropic elements
- wherein the following condition is satisfied:
- −0.20≤I≤0.20
- I
- =
- ∫
- λ
- max
- λ
- min
-
- s
-
- (
- λ
- )
- ·
- cos
-
- (
- 2
-
- π
- /
- λ
- ·
- δ
-
- (
- λ
- )
- )
-
- d
-
-
- λ
- where λ is a wavelength of the light, δ(λ) is a phase difference of the retardation plate, S(λ) is a normalized spectral sensitivity spectrum of the image sensor, and λmax and λmin are the longest wavelength and the shortest wavelength in an integration range that is 10% or more of a peak intensity of the S(λ), respectively.
An optical low-pass filter comprising, in order from the light incident side to the light emitting side, first, second, third, and fourth optical anisotropic elements configured to separate an incident ray into a plurality of rays,
- wherein the first and fourth optical anisotropic elements made of quartz, and the second and third optical anisotropic elements are made of lithium niobate.
Dependencies are inferred from the claim text.