# US 2018/0324368 A1 · Optical system for thermal imager

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- Number: US 2018/0324368 A1
- Document ID: US20180324368A1
- Status: Published application
- Kind: A1
- Application number: 15/770,452
- Filed: 2016-10-12
- Published: 2018-11-08
- Earliest claimed: 2015-10-22
- Assignees: Irlynx
- Applicants: Irlynx
- Inventors: Sandrine OEUVRARD; Christophe MARTINSONS; Benoit TAEYMANS
- Web page: https://patentgrep.com/patent/US20180324368A1

## CPC

- G02B 17/002: {Arrays of reflective systems}
- G02B 5/10: with curved faces
- G02B 13/14: for use with infrared or ultraviolet radiation ({G02B13/008, } G02B13/16 take precedence)
- G02B 17/06: using mirrors only {, i.e. having only one curved mirror (used in non-imaging applications G02B19/00)}
- G02B 27/1066: {for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view}
- G02B 27/143: {using macroscopically faceted or segmented reflective surfaces}
- G03B 17/17: with reflectors arranged in beam forming the photographic image, e.g. for reducing dimensions of camera
- G08B 13/193: using focusing means
- G08B 13/19626: {optical details, e.g. lenses, mirrors or multiple lenses}
- H04N 23/23: from thermal infrared radiation
- H10F 39/8067: {Reflectors}
- G02B 23/06: having a focussing action, e.g. parabolic mirror
- G03B 37/04: with cameras or projectors providing touching or overlapping fields of view
- H10F 39/193: {Infrared image sensors}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)
- G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

The invention relates to an optical system with mirrors for an image sensor, comprising two symmetrical concave mirrors (20a, 20b) arranged in the same plane and having parallel optical axes (Oa, Ob); and an image sensor array (24) arranged in front of the mirrors and having two opposing edges which are respectively substantially adjacent to the optical axes of the two mirrors. The image sensor can be attached to an opaque mask (28) comprising, on the periphery of the image sensor, an entrance pupil (26) in front of each mirror (20), contained in the surface of the mirror extending beyond the image sensor.

## Claims

### Claim 1

An optical system for a thermal imager, comprising:
two symmetrical concave mirrors located in a same plane and having parallel optical axes;
an image sensor array located in front of the mirrors and having two opposite edges respectively substantially adjacent to the optical axes of the two mirrors; and
an opaque mask on which the image sensor is attached, the mask comprising, at the periphery of the image sensor, an entrance pupil in front of each mirror, contained in a surface of the mirror extending beyond the image sensor.

### Claim 2 (depends on 1)

The optical system according to claim 1, wherein each pupil and the corresponding mirror are configured such that:
a ray parallel to the optical axis reaching the mirror through the pupil is reflected towards a nearest edge of the image sensor; and
a ray at a limit angle passing through the pupil and reaching an edge of the mirror under the image sensor is reflected towards an axis of symmetry of the image sensor.

### Claim 3 (depends on 2)

The optical system according to claim 2, wherein the pupils are adjacent respectively to the optical axes.

### Claim 4 (depends on 2)

The optical system according to claim 2, wherein the mirrors have substantially a same form factor as the optical sensor, and have an ellipsoidal surface.

### Claim 5 (depends on 1)

The optical system according to claim 1, comprising:
four concave mirrors with parallel optical axes, configured in four adjacent quadrants, four corners of the image sensor being substantially adjacent respectively to the four optical axes; and
four entrance pupils respectively located at the four corners of the image sensor.