High-resolution angle sensor using multiple peak positions of a double slit interference pattern.

Abstract

A high-resolution angle sensor which uses a double slit (DS) is proposed. By analyzing the positions of intensity peaks in the DS interference pattern, the incident angle of a collimated beam entering the DS is measured. The DS was designed to generate the multiple-order interference pattern with almost even modulation amplitude so that not only the central peak but also multiple side peaks could be used for the measurement. By averaging the incident angle values obtained from each peak position, the angle sensor achieved higher resolution and a smaller periodic nonlinearity error. The performance of the DS angle sensor was tested by comparison with a commercial autocollimator. The Allan deviation of the readout of the angle sensor was 0.0002 in. with the averaging time of 4 s, and the periodic nonlinearity error was evaluated to be less than 0.01 in.