A Real-Time Incoherent Optical Signal Processing System

An electro-optical technique of performing analog sampled-data signal processing operations using the inherently fast matrix multiplication of incoherent optical systems has been under investigation at the Naval Ocean Systems Center for a number of years. Several papers have previously described both a fundamental mathematical treatment and a simplified model of the electro-optical processor (EOP) operation. The present paper will review the characteristics of these processors and, in particular, will describe the results of the characterization and evaluation of an incoherent optical signal processing system consisting of a light-emitting diode (LED), a matrix mask, and a customized charge-coupled device (CCD). Such a processor can perform a broad variety of useful one-dimensional linear transformations such as the Discrete Fourier Transform, multi-channel cross-correlation, and multi-channel matched filtering. The desirability of such a system is due to the high speed, ruggedness, reliability, and compact size which can be achieved with this technology which, in many applications, far surpasses the computational capabilities of conventional digital electronic systems. Based on the results of the comparison of an analytical model of the EOP and the measured performance of the EOP system, conclusions and recommendations concerning the capabilities and limitations of future systems using this technology can be discussed. In addition, a working system capable of performing Fourier transforms at up to 5 megasamples/sec. will be demonstrated.