The modulation transfer function of a source-encoded Hadamard transform imaging system including beam condensing optics is derived. The effects of diffraction, convolution with the encoding apertures, mask motion, and focus errors are considered explicitly. The derived equations are shown to describe resolution of Hadamard transform photothermal deflection imagers with up to 30× condensing optics.
Patrick J. Treado and Michael D. Morris, "Modulation Transfer Function Evaluation of a Hadamard Transform Photothermal Deflection Imaging System with Beam Condensing Optics," Appl. Spectrosc. 42, 1487-1493 (1988)