MODULATION TRANSFER-FUNCTION ASSESSMENT FOR SAMPLED IMAGING-SYSTEM - APPLICATION OF THE GENERALIZED LINE SPREAD FUNCTION TO A STANDARD INFRARED CAMERA

The Line Spread Function (LSF) is a classical figure of merit used to derive the Modulation Transfer Function (MTF) of an imaging system. Ho wever, this test cannot be applied directly to cameras based on an inf rared focal plane array (IRFPA), as these sampled systems exhibit alia sing effects. We have proposed a new technique called Generalized Line Spread Function allowing MTF assessment for sampled imaging systems. The spatial frequency filtering can be tested up to at least twice the Nyquist frequency. The purpose of this paper is to show that this met hod is well-suited to IRFPA cameras. In particular, the effects of a p oor preliminary estimate of the camera characteristics are discussed. Secondly, we have carried out a laboratory experiment with a standard infrared imaging system. The purpose is to provide an experimental dem onstration of the advantages of this new method, not only in terms of performance but also in terms of ease of use and robustness. The infra red imaging system tested is a 512 by 512 Si:Pt IR5120C Mitsubishi cam era equipped with an F/1.2 Angenieux lens.