Pillans, L.A.; (2008) Performance evaluation of an uncooled infrared array camera. Doctoral thesis , University of London.

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Abstract

This thesis describes work carried out on an uncooled pyroelectric infrared array camera with the aim of improving performance and increasing its value in commercial markets. The image processing circuitry of the camera was bypassed and replaced by a purpose built 14 bit digitiser and processing algorithms running on a PC. The constructed digitiser was shown to meet the performance needs of the detector. A model was developed for the camera's performance, taking into account the nature of the chopped pyroelectric detector, and the wavelength passband of the camera. The model suggested that placing a temperature sensor close to the chopper blade of the camera would allow radiometric measurements to be made with the camera. Experimental results verified the predicted camera behaviour and radiometric performance was found to be accurate to within +1.5K when imaging flat fields in a stable thermal environment. Significant distortion and radiometric errors were found when imaging high contrast scenes an algorithm was written to correct this distortion. The algorithm was shown to perform well, drastically reducing distortion and improving radiometric accuracy in all scenes tested. The source of the distortion was not identified, but it is thought to be unrelated to the physical behaviour of the pyroelectric array. The performance of the modified camera is discussed in relation to the current state of the art, and in relation to the performance needs of existing and emerging infrared imaging markets.

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