Raytheon Ti Systems, Inc.

Raytheon Company

Val J Herrera

James A Harder

Keith A Jacobson

A system (10) for calibrating an image detector includes a calibration platform (16) supporting a calibration element (18). The calibration element (18) may be made up of a first portion (20) and a second portion (22), each having a curved surface (20A, 22A) to appropriately alter characteristics of reference light levels (33) generated by a reference source (24). The second portion (22) may have its surface positioned differently to the focal plane array (14) than the first portion (20) for enhanced calibration operation. The reference source (24) generates the reference light levels (33) over a range of temperatures to mimic the image energy generated by the scene (12). The reference source (24) may also include a reference portion element (26) that transmits reference light energy (33) generated by the reference source (24) or reflects scene base energy (34) generated by the scene (12) and allowed to pass through the first portion (20) and the second portion (22). The calibration platform (16) operates to position the first portion (20) and the second portion (22) in front of the focal plane array (14) during calibration operation and remove the first portion (20) and the second portion (22) from in front of the focal plane array (14) during normal image detection.

System and apparatus for calibrating an image detector

An image detection system (10) uses an optical configuration for both image forming and calibration phases of operation. A field lens (20) has an inner portion (36) of a conventional prescription to allow for collection of scene based energy for an opto-electronic approximation of the infrared detail within the afocal field of view by a focal plane array (32). The field lens (20) also has an outer portion (38) that collects far field energy from a scene area (A.sub.I) through a converging point (P.sub.I). The energy collected from the scene area (A.sub.I) is indicative of the average energy level within the scene. The electrical equivalent values of all energy received from the unique area (A.sub.I) is stored in a multidimensional range used for subsequent gain and offset calibration coefficient calculations.

Passive scene base calibration system

An image detection system (10) includes a derotation optics assembly (24) that stabilizes images viewed from a scene (14) by individual detector elements (31) in a focal plane array (32). The derotation optics assembly (24) also is used in providing scene based calibration to the individual detector elements (31). The derotation optics assembly (24) places images viewed from the scene (14) in a first rotation position. The individual detector elements (31) collect scene based energy at the first rotation position. The derotation optics assembly (24) places images viewed from the scene (14) in a second rotation position. The individual detector elements (31) collect scene based energy at the second rotation position. Comparisons are made among outputs of the individual detector elements (31) at the first and second rotation positions. Correction factors for each of the individual detector elements (31) are adjusted in response to the comparisons in order to compensate for the differing voltage offsets and gains among the individual detector elements (31).

Method and apparatus for calibrating a focal plane array of an image

A system (10) for calibrating an image detector includes a calibration platform (16) supporting a calibration element (18). The calibration element (18) may be made up of a first lens (20) and a second lens (22), each having a curved surface to appropriately alter characteristics of reference light levels (33) generated by a reference source (24). The second lens (22) may have its surface positioned differently to the focal plane array (14) than the first lens mirror (20) for enhanced calibration operation. The reference source (24) generates the reference light levels (33) over a range of temperatures to mimic the image energy generated by the scene (12). The reference source (24) may also include a reference lens element (26) that transmits reference light energy (33) generated by the reference source (24) or reflects scene base energy (34) generated by the scene (12) and allowed to pass through the first lens (20) and the second lens (22). The calibration platform (16) operates to position the first lens (20) and the second lens (22) in front of the focal plane array (14) during calibration operation and remove the first lens (20) and the second lens (22) from in front of the focal plane array (14) during normal image detection.

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Double Oak, TX, United States of America

Val J Herrera