Birefringence effects in estar base reconnaissance film in an optical correlator

Coherent optical correlators using Fourier transform matched filters are generally constructed using the interference between a transformed signal beam and an equipolarized collimated coherent reference beam. Polarization effects of any system elements must be accounted for in using such a correlator, or in any system using holographic techniques, particularly if analysers are used. Birefringence effects of estar base film, used almost exclusively in aerial reconnaissance work, have been examined by the authors when such film is placed in the signal path. Methods of compensation for such effects are suggested.