Limiting capabilities of self-mixing interferometry upon sawtooth modulation of a semiconductor laser wavelength

Abstract

This paper discusses a self-mixing interferometry method for measuring distances upon sawtooth modulation of the wavelength of laser radiation. Conditions under which the distance obtained from the spectrum of the modeled autodyne signal coincides with the distance specified in computer simulation are determined. The limiting capabilities of the method are theoretically substantiated for the increased range of deviations of the laser wavelength. The estimation of the limiting capabilities of the distance measurement method on the spectrum of the autodyne signal gives 10 microns at a wavelength of 650 nm at a 5-nm deviation of laser radiation wavelength. We also discuss difficulties of attaining the limiting accuracy of distance measurements associated with the nonlinear dependence of the wavelength emitted by a laser diode on its supply current and the need to analyze the self-mixing signal at high frequencies.

Keywords

• semiconductor laser
• self-mixing interferometry
• distance measurement
• wavelength modulation