Digital Processing Technique for Quasi-white Light Interference Signal

摘要

A digital processing method for quasi-white light interference signal is proposed in the paper. A circuit based on EPP (Enhanced Parallel Port) is designed for high speed synchronous collecting. Envelope signals collecting is realized by means of interference fringe pulses synchronization, with the result that the space-domain interference envelope signals can be restored with high accuracy. A high accuracy algorithm for finding the acme of interference envelope signals, namely the point of zero optical path difference, is proposed in the paper. Compared with the traditional processing method based on analog circuit, the new method overcomes the time-domain wave distortion of quasi-white light signal caused by the uneven moving velocity, therefore, the errors caused by the distortion are eliminated. The method is applied in the interference signal processing of long coherent length. In the paper, the proposed method is emulated with computer and proved by experiments, and the results indicate that the locating accuracy of the points of zero optical path difference of fiber quasi-white interference signal is better than 0.5 interference fringes.