US6862147B1
Expired / Lapsed
US
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Decentered field lens with tilted focal plane array
Assignee: United States Department of the Army
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Filing: 2003-10-23
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Granted: 2005-03-01
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Expires: 2023-10-23
Abstract
Abstract An IR sensor device in accordance with the present invention includes an optical train, a focal plane array (FPA) for receiving incoming ray bundles that have passed through the optical train, and a decentered plano-convex field lens positioned therebetween the filed lens is decentered in that it is positioned so that the optical axis intersects the fields lens at an offset distance from the geometric center of the lens perimenter. When the field lens is positioned in this manner, optical ray bundles that pass through the field lens establish a revised image plane. To compensate for the revised image plane, the FPA is titled until the FPA is co-planar with the revised image plane. Any reflected optical ray bundles are refracted as they pass back through the field lens and directed away from the pupil, to prevent reflected optical ray bundles from entering the optical train and leaving the sensor as an IR retro-reflection during operation of the device.
Inventors
- 👤 Jamie Sonstroem
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:13
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/16; G02B23/00; G02B23/12
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
101 words
An imaging device comprising: an optical train for receiving optical ray bundles, said optical train defining an optical axis; a focal plane array arranged for detecting said optical ray bundles; a field lens positioned between said optical train and said focal plane array, said field lens having a planar surface, an opposing convex surface and a lens perimeter that defines a geometric center; said lens perimeter having at least one straight edge and one curved edge; and, said field being decentered with said device so that said optical axis intersects said field lens at an offset distance from said geometric center.
Claim 2
Dependent Claim
101 words
An imaging device comprising: an optical train for receiving optical ray bundles, said optical train defining an optical axis; a focal plane array arranged for detecting said optical ray bundles; a field lens positioned between said optical train and said focal plane array, said field lens having a planar surface, an opposing convex surface and a lens perimeter that defines a geometric center; said lens perimeter having at least one straight edge and one curved edge; and, said field being decentered with said device so that said optical axis intersects said field lens at an offset distance from said geometric center.
Claim 3
Dependent Claim
17 words
The device of claim 1 wherein said lens perimeter has two straight edges and a curved edge.
Claim 4
Dependent Claim
19 words
The device of claim 2 wherein said wherein said straight edges are perpendicular and have an equal edge length.
Claim 5
Dependent Claim
31 words
The device of claim 1 wherein said field lens has a planar surface that is normal to said optical axis and an opposing convex surface that faces said focal plane array.
Claim 6
Dependent Claim
35 words
The device of claim 4 wherein said focal plane array is tilted so that said optical ray bundles, after passing through said field lens, impinge on said focal plane array at a constant incidence angle.
Claim 7
Dependent Claim
15 words
The device of claim 5 wherein said field lens is made of non-linear optical material.
Claim 8
Dependent Claim
105 words
An imaging apparatus comprising: an optical train for receiving optical ray bundles, said optical train defining an optical axis; a focal plane array arranged for detecting said optical ray bundles; a field lens positioned between said optical train and said focal plane array so that said optical ray bundles pass therethrough; said field lens having a rectangular lens perimeter with four lens corriers; and, said field lens having a lens thickness measured from said planar surface to said convex surface, said lens thickness having a spherical decrease from a maximum thickness at one of said corners to a lesser thickness at each respective remaining corner.
Claim 9
Dependent Claim
105 words
An imaging apparatus comprising: an optical train for receiving optical ray bundles, said optical train defining an optical axis; a focal plane array arranged for detecting said optical ray bundles; a field lens positioned between said optical train and said focal plane array so that said optical ray bundles pass therethrough; said field lens having a rectangular lens perimeter with four lens corriers; and, said field lens having a lens thickness measured from said planar surface to said convex surface, said lens thickness having a spherical decrease from a maximum thickness at one of said corners to a lesser thickness at each respective remaining corner.
Claim 10
Dependent Claim
28 words
The apparatus of claim 7 wherein said field lens has planar surface normal to said optical axis and an opposing convex surface that faces said focal plane array.
Claim 11
Dependent Claim
22 words
The apparatus of claim 8 wherein said field lens is positioned so that said rectangular perimeter is centered on said optical axis.
Claim 12
Dependent Claim
16 words
The apparatus of claim 7 wherein said field lens is made of a non-linear optical material
Claim 13
Dependent Claim
82 words
An imaging device comprising: an optical train for receiving optical ray bundles, said optical train defining an optical axis; a focal plane array for detecting said optical ray bundles; a circular field lens positioned between said optical train and said focal plane array, said field lens having a geometric center when viewed in top plan; and, said circular field lens aligned on said optical axis so that said optical axis intersects said field lens at an offset distance from said geometric center.
Claim 14
Dependent Claim
82 words
An imaging device comprising: an optical train for receiving optical ray bundles, said optical train defining an optical axis; a focal plane array for detecting said optical ray bundles; a circular field lens positioned between said optical train and said focal plane array, said field lens having a geometric center when viewed in top plan; and, said circular field lens aligned on said optical axis so that said optical axis intersects said field lens at an offset distance from said geometric center.
Claim 15
Dependent Claim
36 words
The device of claim 11 wherein said circular field lens has a planar incident surface and an opposing convex surface, said incident surface normal to said optical axis, said convex surface facing said focal plane array.
Claim 16
Dependent Claim
16 words
The device of claim 11 wherein said field lens of made of a non-linear optical material.
Claim 17
Dependent Claim
13 words
The device of claim 11 wherein said field lens has opposing convex surfaces.
Claim 18
Independent Claim
101 words
A method for minimizing retro-reflection from an imaging device comprising the steps of: (A) receiving optical ray bundles through an optical train that defines an optical axis; (B) arranging a focal plane array in a manner that allows said optical ray bundles to impinge on said focal plane array; (C) affording a field lens having a geometric center when viewed in top plan; and, (D) positioning said field lens between said optical train and said focal plane array so that said field lens is decentered and said optical axis intersects said field lens at an offset distance from said geometric center.
Claim 19
Independent Claim
101 words
A method for minimizing retro-reflection from an imaging device comprising the steps of: (A) receiving optical ray bundles through an optical train that defines an optical axis; (B) arranging a focal plane array in a manner that allows said optical ray bundles to impinge on said focal plane array; (C) affording a field lens having a geometric center when viewed in top plan; and, (D) positioning said field lens between said optical train and said focal plane array so that said field lens is decentered and said optical axis intersects said field lens at an offset distance from said geometric center.
Claim 20
Dependent Claim
99 words
The method of claim 15 wherein said field lens is circular and further comprising the step of: (E) removing a portion of said field lens to establish a quarter-circle section; having perpendicular straight edges of equal length and a third arcuate edge; and, (F) milling said arcuate edge to establish a rectangular field lens having a rectangular perimeter when observed in plan view, said rectangular field lens; (G) reestablishing a geometric center for said rectangular field lens; and, (H) accomplishing step (D) so that said optical axis passes through said geometric center, step (H) being performed after step (G).
Claim 21
Dependent Claim
29 words
The method of claim 16 wherein said step (C) further comprises the step of: (I) shaping said field lens with a planar incident surface and an opposing convex surface.
Claim 22
Dependent Claim
33 words
The method of claim 17 wherein said step D) is accomplished so that said optical ray bundles are incident on said planar incident surface and said convex surface faces said focal plane array.
Claim 23
Dependent Claim
48 words
The method of claim 18 wherein said step D) establishes a revised image plane that intersects a plane containing the focal plane array, and further comprising the step of: (J) tilting said focal plane array so that said-focal plane array is co-planar with said revised image plan to.
References Cited (Backward Citations)
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