Freeform surface reflective infrared imaging system

Patent metadata

Field	Value
Publication number	US-11371889-B2
Application number	US-202016916016-A
Country	US
Kind code	B2
Filing date	Jun 29, 2020
Priority date	Aug 1, 2019
Publication date	Jun 28, 2022
Grant date	Jun 28, 2022

Abstract

The present invention relates to a freeform surface reflective infrared imaging system comprising a primary mirror, a secondary mirror, a tertiary mirror, and an infrared light detector. Each reflective surface of the primary mirror, the secondary mirror, and the tertiary mirror is an xy polynomial freeform surface. A field of view of the freeform surface reflective infrared imaging system is larger than or equal to 40°×30°. An F-number of the freeform surface reflective infrared imaging system is less than or equal to 1.39.

First claim

What is claimed is:

1. A freeform surface reflective infrared imaging system, comprising:
a primary mirror, wherein a first three-dimensional rectangular coordinates system (X,Y,Z) is defined with a vertex of the primary mirror as a first origin, and in the first three-dimensional rectangular coordinates system (X,Y,Z), a reflective surface of the primary mirror is an xy polynomial freeform surface;
a secondary mirror, wherein a second three-dimensional rectangular coordinates system (X′,Y′,Z′) is defined with a vertex of the secondary mirror as a second origin, and the second three-dimensional rectangular coordinates system (X′,Y′,Z′) is obtained by moving the first three-dimensional rectangular coordinates system (X,Y,Z) along a Z-axis negative direction and a Y-axis negative direction, and in the second three-dimensional rectangular coordinates system (X′,Y′,Z′), a reflective surface of the secondary mirror is an x′y′ polynomial freeform surface;
a tertiary mirror, wherein a third three-dimensional rectangular coordinates system (X″,Y″,Z″) is defined with a vertex of the tertiary mirror as a third origin, and the third three-dimensional rectangular coordinates system (X″,Y″,Z″) is obtained by moving the second three-dimensional rectangular coordinates system (X′,Y′,Z′) along a Z′-axis positive direction and a Y′-axis negative direction, and in the third three-dimensional rectangular coordinates system (X″,Y″,Z″), a reflective surface of the tertiary mirror is an x″y″ polynomial freeform surface;
an infrared light detector, wherein a plurality of feature rays are successively reflected by the primary mirror, the secondary mirror and the tertiary mirror to form an image on an infrared light detector;
a field of view of the freeform surface reflective infrared imaging system is larger than or equal to 40°×30°, and an F-number of the freeform surface reflective infrared imaging system is less than or equal to 1.39.

2. The system of claim 1 , wherein the second three-dimensional rectangular coordinates system (X′,Y′,Z′) is obtained by moving the first three-dimensional rectangular coordinates system (X,Y,Z) for about 19.985 mm along a Y-axis negative direction, and then moving for about 54.736 mm along a Z-axis negative direction, and then rotating along the counterclockwise direction for about 102.365° with the X axis as the rotation axis.

3. The system of claim 1 , wherein the third three-dimensional rectangular coordinates system (X″,Y″,Z″) is obtained by moving the second three-dimensional rectangular coordinates system (X′,Y′,Z′) for about 27.254 mm along a Z′-axis positive direction, and then moving for about 9.489 mm along a Y′-axis negative direction, and then rotating along the clockwise direction for about 99.526° with the X′-axis as the rotation axis.

4. The system of claim 1 , wherein the reflective surface of the primary mirror is sixth-order polynomial freeform surface of xy without odd items of x.

5. The system of claim 4 , wherein an equation of the sixth-order polynomial freeform surface of xy can be expressed as follows:

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6

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10

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13

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Assignees

• Univ Tsinghua
• Hon Hai Prec Ind Co Ltd

Inventors

• Wu Wei-Chen
• Zhu Jun
• Jin Guo-Fan
• Fan Shou-Shan

Classifications

• G01J2005/0077

  Imaging · CPC title

• G01J5/0215

  Compact construction · CPC title

• G01J5/0846 Primary

  having multiple detectors for performing different types of detection, e.g. using radiometry and reflectometry channels · CPC title

• G01J5/0806 Primary

  Focusing or collimating elements, e.g. lenses or concave mirrors · CPC title

• G01J5/07

  Arrangements for adjusting the solid angle of collected radiation, e.g. adjusting or orienting field of view, tracking position or encoding angular position (optical collimating elements G01J5/0806) · CPC title