Diffraction grating lens and method of producing the same, and imaging device in which the same is used
First Claim
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1. A diffraction grating lens comprising:
- a lens body; and
a diffraction grating provided on a surface of the lens body, the diffraction grating including a plurality of annular zones having slopes inclined along a width direction and a plurality of step surfaces respectively located between the plurality of annular zones, whereinat least one of the plurality of annular zones extends from a first one of the step surfaces to a second one of the step surfaces and is light-transmissive across an entire area thereof along a width direction, and in the at least one annular zone from the first one of the step surfaces to the second one of the step surfaces, a light transmittance near at least one of two ends along the width direction is smaller than a light transmittance near a central portion along the width direction; and
in the at least one annular zone, a surface roughness of the slope near at least one of the two ends along the width direction is greater than a surface roughness of the slope near the central portion along the width direction of the annular zone.
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Abstract
A diffraction grating lens according to the present invention includes a lens body and a diffraction grating provided on the surface of the lens body, the diffraction grating including a plurality of annular zones having slopes inclined along a width direction and a plurality of step surfaces respectively located between the plurality of annular zones. At least one of the plurality of annular zones is light-transmissive across its entire area along the width direction, and in the at least one annular zone, a light transmittance near at least one of two ends along the width direction is smaller than a light transmittance near a central portion along the width direction.
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11 Claims
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1. A diffraction grating lens comprising:
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a lens body; and a diffraction grating provided on a surface of the lens body, the diffraction grating including a plurality of annular zones having slopes inclined along a width direction and a plurality of step surfaces respectively located between the plurality of annular zones, wherein at least one of the plurality of annular zones extends from a first one of the step surfaces to a second one of the step surfaces and is light-transmissive across an entire area thereof along a width direction, and in the at least one annular zone from the first one of the step surfaces to the second one of the step surfaces, a light transmittance near at least one of two ends along the width direction is smaller than a light transmittance near a central portion along the width direction; and in the at least one annular zone, a surface roughness of the slope near at least one of the two ends along the width direction is greater than a surface roughness of the slope near the central portion along the width direction of the annular zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of producing a diffraction grating lens having
a lens body, and a diffraction grating provided on a surface of the lens body, the diffraction grating including a plurality of annular zones having slopes inclined along a width direction and a plurality of step surfaces respectively located between the plurality of annular zones, wherein at least one of the plurality of annular zones extends from a first one of the step surfaces to a second one of the step surfaces and is light-transmissive across an entire area thereof along a width direction, and in the at least one annular zone from the first one of the step surfaces to the second one of the step surfaces, a light transmittance near at least one of two ends along the width direction is smaller than a light transmittance near a central portion along the width direction; - and
in the at least one annular zone, a surface roughness of the slope near at least one of the two ends along the width direction is greater than a surface roughness of the slope near the central portion along the width direction of the annular zone, the method comprising; a step of proving a lens body having the diffraction grating on a surface thereof; and a step of pressing a mold against the diffraction grating on the surface of the lens body, with a material having a lower light transmittance than that of the lens body being applied on the mold.
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Specification