Design, test, and operation of a small thermal imaging core

Patent metadata

Field	Value
Publication number	US-11774293-B2
Application number	US-202217661446-A
Country	US
Kind code	B2
Filing date	Apr 29, 2022
Priority date	Jun 21, 2017
Publication date	Oct 3, 2023
Grant date	Oct 3, 2023

Abstract

An ultra-small thermal imaging core, or micro-core. The design of the micro-core may include substrates for mounting optics and electronic connectors that are thermally matched to the imaging Focal Plane Array (FPA). Test fixtures for test and adjustment that allow for operation and image acquisition of multiple cores may also be provided. Tooling may be included to position the optics to set the core focus, either by moving the lens and lens holder as one or by pushing and/or pulling the lens against a lens positioning element within the lens holder, while observing a scene. Test procedures and fixtures that allow for full temperature calibration of each individual core, as well as providing data useful for uniformity correction during operation may also be included as part of the test and manufacture of the core.

First claim

What is claimed is:

1. A method for correcting for offset drift in a thermal imager including a focal plane array (FPA) of photodetectors, including a FPA ambient temperature sensor configured to observe a thermal scene and convert the thermal scene information to a plurality of image frames whose pixels correspond to individual photodetectors in the array, the method comprising:
providing a non-uniformity correction in the form of an offset value from a desired value for at least one pixel at a given FPA ambient temperature;
updating the non-uniformity correction at at least one different FPA ambient temperature;
developing a relationship between offset variation and temperature sensor reading; and
using the relationship to apply an offset correction derived from the temperature sensor reading to image data during imaging operation of the thermal imager,
wherein the offset correction is performed during actual use of the imager and is used to update or replace any preexisting offset drift correction data, and
wherein the imager initiates the offset correction in response to detecting, based on one or more frames of image data from the FPA, that a flat scene is being imaged.

2. The method of claim 1 wherein the preexisting offset drift correction data is obtained by a calibration operation that is part of the initial testing of the imager.

3. The method of claim 2 wherein the preexisting offset drift correction data is based on an offset collection operation performed at manufacturing testing, and wherein the relationship is stored for use during operation.

4. The method of claim 1 wherein the offset correction is determined at a discrete number of temperature sensor readings and the relationship is a curve fit to the offset correction data points.

5. The method of claim 1 wherein the offset correction is performed during operation of the thermal imager by:
observing the flat scene at a first temperature sensor value and determining a non-uniformity correction offset data set;
observing the flat scene at at least one different temperature sensor value and determining the difference in offset data set;
developing the relationship from the operationally observed flat scenes at different FPA temperature and apply offsets derived from the relationship at other temp sensor readings.

6. The method of claim 5 wherein the imager is further configured to initiate an offset correction in response to an input from the user while the imager is directed at a flat scene by the user.

7. The method of claim 5 wherein observing the flat scene at at least one different temperature sensor value comprises, responsive to an initiation of the offset correction and subsequent to observing the flat scene at the first temperature sensor value, initiating at least one of power saving or power using operations, wherein an increase or decrease in resistive heating associated with the power saving or power using operations at least partially causes a local ambient temperature change from a first temperature associated with the first temperature sensor value to a second temperature associated with the different temperature sensor.

Assignees

• Seek Thermal Inc

Inventors

• Parrish William J
• Engberg Andreas
• Wolfe Jason
• Moran Derek
• Henry Blake
• Williams Ross
• Mead Russ

Classifications

• H04N23/23

  from thermal infrared radiation · CPC title

• G01J5/0205 Primary

  Mechanical elements; Supports for optical elements · CPC title

• G01J5/0215

  Compact construction · CPC title

• G01J5/0806

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

• G01J5/20

  using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices · CPC title