Phase-Shifting laser diode interferometry with equal phase steps using a Fabry-Perot cavity

摘要

A phase-shifting interferometer (PSI) with equal phase steps, using a frequency-tunable diode laser and a Fabry-Perot cavity, is proposed for the Carre algorithm. The measurement accuracy of the Carre algorithm depends on the equality of the phase steps. Using the Fabry-Perot cavity as a highly stable optical frequency reference, a high degree of phase step equality can be realized in the PSI with an optical frequency shift. Our experimental scheme realizes an optical frequency step equality higher than 2.1 x 10~(-5) and a measurement repeatability of λ/850.