Interferential Wavelengths Comparison With Real-Time Signal Processing

The two wave field widened interferometer of "Institut National de Metrologie" (I.N.M.) is controlled by Micral R2E microprocessor (Intel 8008) for data acquisition and real time signal processing. Two different methods are described, one involving a servo controlled step by step scanning of the path difference, in the second one this scanning is approximately linear with time, and the microprocessor samples interferometric signal at a high rate. In both methods a real time signal processing is achieved. We compare the results of phase measurements by the two methods ; the reproducibility may be in both cases within a few 10 -4 of a fringe.