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.

High-precision two-dimensional angle sensor using a dot array of a diffractive optical element

“…In the autocollimation principle, angular displacement is obtained by measuring positional shift of a reticle image or a focused spot on an image plane of an imaging lens. Therefore, to obtain higher resolution, focal length of the image lens should be increased or some techniques enhancing the resolution of positional shift detection should be introduced [4][5][6][7]. Several commercial * Author to whom any correspondence should be addressed.…”

“…Some works on increasing resolution even with a short focal length imaging lens were reported. These include the optical enlargement technique [4], or techniques using a specially designed phase grating [5], a reticle having multiple slits [6], or a double-slit [7]. The averaging effect reduced random errors from digitization and photon noise, and achieved higher resolution than conventional autocollimators [6,7].…”

“…These include the optical enlargement technique [4], or techniques using a specially designed phase grating [5], a reticle having multiple slits [6], or a double-slit [7]. The averaging effect reduced random errors from digitization and photon noise, and achieved higher resolution than conventional autocollimators [6,7]. However, when an angle sensor was implemented using a double-slit plate, it showed rather large nonlinearity caused by a wavefront error of a collimated beam, because the doubleslit interference pattern is generated by the incident beam passing though very narrow slits of which width is several micrometers [7].…”

“…The averaging effect reduced random errors from digitization and photon noise, and achieved higher resolution than conventional autocollimators [6,7]. However, when an angle sensor was implemented using a double-slit plate, it showed rather large nonlinearity caused by a wavefront error of a collimated beam, because the doubleslit interference pattern is generated by the incident beam passing though very narrow slits of which width is several micrometers [7]. In this article, a high-precision two-dimensional (2D) angle sensor is presented, which employs a diffractive optical element (DOE) generating a 2D dot array.…”

“…In this article, a high-precision two-dimensional (2D) angle sensor is presented, which employs a diffractive optical element (DOE) generating a 2D dot array. Comparing with the prior researches [4][5][6][7], originalities of this paper are to expand the high-resolution angle measurement strategy to two-axis case and reduce nonlinearity error effectively, using a DOE rather than a multiple-slit reticle or a double-slit plate. They also can be implemented as a small-sized sensor module with a simple configuration.…”