Parasitic Flux Analysis of Cooled Infrared Detectors for Space Applications

  • Ankur Jain Space Applications Centre, ISRO, Ahmedabad
  • Amiya Biswas Space Applications Centre, ISRO, Ahmedabad
Keywords: Parasitic flux, Long wave infrared, Integrated Detector, Imager, Stray light, Ray trace


An infrared imager measures radiations emitted by an object in specified spectral bands to determine change in object’s characteristics over a period of time. A typical infrared imager consists of focusing optics and a cryogenically cooled two-dimensional infrared detector array mounted on the cold tip of an active micro-cooler vacuum sealed with an optical window, typically known as integrated detector cooler assembly (IDCA). Detection of feeble radiant flux from the intended target in a narrow spectral band requires a highly sensitive low noise sensor array with high well capacity. However, in practical applications the performance of an infrared imager is limited by the parasitic thermal emissions from optical elements and emissions from IDCA components like vacuum window, Dewar walls which are generally kept at ambient temperature. To optimise the performance of imager it becomes imperative to estimate these parasitic fluxes and take corrective actions to minimise their effects. This paper explains an analytical model developed to estimate parasitic fluxes generated from different components of a long wave infrared imager. Validation of the developed model was carried out by simulations in ZEMAX optical design software using ray trace method after analytical computations in MATLAB.

Author Biographies

Ankur Jain, Space Applications Centre, ISRO, Ahmedabad

Mr Ankur Jain joined Space Applications Centre, ISRO in 2006. Currently he is working on design and development of Infrared detectors for space applications. He developed the parasitic flux model of infrared imager and carried out the required simulations for model validation.

Amiya Biswas, Space Applications Centre, ISRO, Ahmedabad
Dr Amiya Biswas received his MSc optics and optoelectronics from University of Calcutta in 1995 and PhD in optical engineering from Loughborough University in 2007. He joined Indian Space Research Organisation as a Scientist in 1997. His research interests include optical design, analysis and simulations. The optical design of the imager and validation of the analytical model presented in this paper was carried out under his guidance.
How to Cite
Jain, A., & Biswas, A. (2017). Parasitic Flux Analysis of Cooled Infrared Detectors for Space Applications. Defence Science Journal, 67(2), 193-197.
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