Coherent optical Fourier transformation of infrared interferograms.

The property of a spherical lens, to display the two-dimensional Fourier transform of an input function, is used for the Fourier transformation of symmetrical infrared interferograms. These are represented in form of transparent variable area masks with amplitude transmittance ±1. The optically generated spectrum is compared with the digital computer spectrum. The maximum deviation in the peak positions is about 2 cm-1. Real time operation of the optical analogue computer and the coherent optical Fourier transformation of asymmetric interferograms are discussed