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IR sensor performance testing with a double-slit method

Author: Jong, A.N. de · Winkel, J. · Ghauharali, R.
Publisher: SPIE
Place: Bellingham, WA.
Institution: TNO Fysisch en Elektronisch Laboratorium
Source:Infrared Imaging Systems: Design, Analysis, Modeling and Testing XII, 18-19 April 2001, Orlando, Fl, USA, 1-11
Proceedings of SPIE
Identifier: 95394
doi: doi:10.1117/12.439141
Keywords: Physics · Cameras · Image sensors · Optical resolving power · Performance · Phase modulation · Rayleigh scattering · Infrared cameras · Infrared imaging


Determination of the performance of undersampled IR cameras by means of four-bar patterns suffers from aliasing for spatial frequencies above the Nyquist limit. An alternative method, using two parallel line sources, is described. This method avoids the aliasing effect and allows a reproduceable way for performance measurements by simple variation of the spacing between the two line sources and their temperatures. The modulation depth at optimum phase is measured in the camera display or electronics, similar to the classical Rayleigh criterion. Additional benefits of the new method are the simple target construction (only one target is required) and the ease to model line sources. The result of a performance measurement is similar to the standard MRTD (Minimum Resolvable Temperature Difference) method, where sensor resolution is coupled to range for a given target size and contrast. The new method has therefore the potential to be implemented into the present STANAG4347 and 4349. Results of performance measurements, carried out with the uncooled Thermacam PM395 camera and other cameras, are shown. Predicted and measured performance agree very well.