In correlation filtering a spatial light modulator is traditionally modeled as affecting only the phase or only the amplitude of light. Usually, however, a single operating parameter affects both phase and amplitude. An integral constraint is developed that is a necessary condition for optimizing a correlation filter having single parameter coupling between phase and amplitude. The phase-only filter is shown to be a special case.
Richard D. Juday, "Correlation with a spatial light modulator having phase and amplitude cross coupling," Appl. Opt. 28, 4865-4869 (1989)