The Navy is currently investigating the possible use of cepstral processing in existing and future fire control subsystems. The cepstruxn is difficult to implement in real time using digital electronics. However, if a real time optical logarithm can be generated, then the optical cepstrum can be implemented in a real time system. A real time optical logarithmic transform has been demonstrated at frame rates of 10 kHz using the thresholding capability of an Amorphous Silicon, Ferroelectric, Liquid Crystal, Spatial Light Modulator (ASFLC-SLM). As such, it is an advance over current systems, which use either photographic film as a thresholding device or a Hughes light valve that operates at frame rates of less than 50 Hz. Using experimental data, the relation between the input and output intensities of the system has been shown to be logarithmic over the input range of three to ten milliwatts. Using characteristics of our halftone screen and ASFLC-SLM, it has been possible to compute theoretical values of the output intensity from this system. These results agree nicely with those obtained experimentally.