Imaging lens for infrared cameras
First Claim
Patent Images
1. An infrared imaging device, comprising:
- first and second plastic Fresnel lens elements, wherein said first and second lens elements are in optical communication with each other, and wherein each of said first and second lens elements has a first major surface which is convex and a second major surface which comprises a Fresnel surface;
wherein said first lens element is adapted to mimic a meniscus asphere correct for conjugates of infinity and for the focal length of said first lens element, and wherein said second lens element is adapted to mimic a meniscus asphere and is further adapted to act as a field flattener.
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Abstract
An infrared imaging device is provided which comprises first and second plastic Fresnel lenses that are in optical communication with each other. Each of the first and second lenses have a first major surface which is convex and a second major surface which comprises a Fresnel surface. The first lens is adapted to mimic a meniscus asphere correct for conjugates of infinity and for the focal length of said first lens, and the second lens is adapted to mimic a meniscus asphere and is further adapted to act as a field flattener.
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Citations
51 Claims
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1. An infrared imaging device, comprising:
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first and second plastic Fresnel lens elements, wherein said first and second lens elements are in optical communication with each other, and wherein each of said first and second lens elements has a first major surface which is convex and a second major surface which comprises a Fresnel surface;
wherein said first lens element is adapted to mimic a meniscus asphere correct for conjugates of infinity and for the focal length of said first lens element, and wherein said second lens element is adapted to mimic a meniscus asphere and is further adapted to act as a field flattener. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An infrared imaging device, comprising:
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first and second plastic Fresnel lens elements in optical communication with each other;
wherein said first lens element has positive power and said second lens element also has positive power. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29)
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23. The infrared imaging device of claim 23, wherein said second lens element is also adapted to act as a meniscus asphere, and wherein said second lens element is further adapted to act as a field flattener.
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30. An infrared imaging lens, comprising:
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first and second plastic lens elements, each of said lens elements having a first major surface which is convex and a second major surface which comprises a Fresnel surface;
wherein the Fresnel surface of at least one of the first and second lens elements comprises a series of grooves that are convex in a cross-section taken along a plane perpendicular to the second major surface of the lens element. - View Dependent Claims (31, 32, 33, 34, 35, 36)
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37. An infrared imaging device, comprising:
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first and second plastic lens elements, each having a first major surface which is convex and a second major surface which comprises a Fresnel surface that comprises a series of grooves, wherein each of said grooves is aspherical in a cross-section taken along a plane perpendicular to the length of the groove;
a chassis which supports said first and second lens elements in a fixed orientation with respect to each other along a longitudinal axis;
a mechanism adapted to adjust the distance between the first and second lens elements along the longitudinal axis; and
a focal plane array detector;
wherein said first and second lens elements are arranged within said chassis such that they are in optical communication with each other and such that their first major surfaces face away from the focal plane array detector. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45)
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46. A method for making an infrared thermal imaging device, comprising the steps of:
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shaping first and second lens elements from a softened polymeric composition such that said first and second lens elements each have a first major surface which is convex and a second major surface which comprises a Fresnel surface that contains a series of grooves, each of which is aspherical in a cross-section taken along a plane perpendicular to the length of the groove; and
disposing the first and second lens elements in a housing equipped with a focal plane array such that said first and second lens elements are in optical communication with each other and have their first major surfaces facing away from the focal plane array. - View Dependent Claims (47, 48, 49)
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50. An infrared imaging device, comprising:
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first and second plastic Fresnel lens elements in optical communication with each other, wherein each of said first and second lens elements have positive power;
a chassis which supports said first and second lens elements in a fixed orientation with respect to each other along a longitudinal axis;
a mechanism adapted to adjust the distance between the first and second lens elements along the longitudinal axis; and
a focal plane array detector. - View Dependent Claims (51)
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Specification