TWO-WAVELENGTH LASER-DIODE INTERFEROMETER WITH FRACTIONAL FRINGE TECHNIQUES

摘要

A two-wavelength interferometer with a fractional fringe technique (the method of coincidence) has been constructed by using dual frequency-ramped laser diodes. The respective wavelengths of two optical phases were measured by the heterodyne technique. The detected two phases are employed with real-time electronic processing to produce two signals that correspond to the integer and the fractional fringe numbers at a single wavelength. These summed signals can yield a synthetic phase having a single-wavelength resolution. The upper Limits for the measurement accuracy are theoretically analyzed. [References: 15]