White Paper

Expanding The Dynamic Range Of Short Wave Infrared (SWIR) Imagery

Source: Sensors Unlimited - UTC Aerospace Systems

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White Paper: Expanding The Dynamic Range Of Short Wave Infrared (SWIR) Imagery

By Marc Hansen, Sensors Unlimited, Inc.

Advances have been made in short wave infrared (SWIR) imaging technology to address the most demanding imaging and surveillance applications. Multiple techniques have been developed and deployed in Goodrich's SWIR indium gallium arsenide (InGaAs) cameras to increase the dynamic range performance of standard, commercial off-theshelf (COTS) products. New developments have been implemented on multiple levels to give these cameras the unique ability to automatically compensate for changes in light levels of up to five orders of magnitude, while improving intra-scenic dynamic range through raw data acquisition techniques, and a proprietary, patent-pending, image-enhancement algorithm.

The pixel architecture used to acquire data over this large range of scene intensities is unique to Goodrich SWIR cameras. The focal plane array (FPA), or lightsensing chip, is composed of an InGaAs chip bumpbonded to a silicon read-out integrated circuit (ROIC) that has the ability to continuously change the in-pixel analog gain without the limitations of the fixed integration capacitors found in capacitive transimpedance amplifier (CTIA) ROICs used by other camera manufacturers. Commonly, CTIA pixel architecture is limited to two capacitors, and therefore only two different gain settings due to pixel size constraints.

The gate-modulated (GMOD) pixel architecture ROIC can change the sensitivity of the focal plane array by modifying internal biases, resulting in a change in effective capacitance. The flexibility of an infinitely variable capacitance results in an infinitely variable full well capacity for the GMOD ROIC. This allows the camera to adjust its sensitivity and full well capacity to compensate for large changes in scene intensity without the integration capacitor limitations of a CTIA ROIC.

Click Here To Download:
White Paper: Expanding The Dynamic Range Of Short Wave Infrared (SWIR) Imagery

Sensors Unlimited - UTC Aerospace Systems