Interferometric distance measurement appts. - has variable wavelength and reference sources with common spectral region and forms optically isolated measurement and reference interferometers and detects difference frequency w.r.t. reference frequency

摘要

The radiation sources include a stabilised laser diode (1), the variable laser diode (2) and the variable laser diode (3) with the frequency doubling crystal (3a). One second stable frequency source at least can be used as a reference wavelength or frequency. The radiations are collimated, optically isolated, united, divided, reflected, reunited, separated and detected. The double interferometric systems form respectively a measurement interferometer and a reference interferometer eg Fabry-Perot . The two radiations are passed through them, and a separate detection of the interference phenomena of each individual radiation is ensured. Photo sensors detect the difference frequency of the radiation compared to the reference frequency. The received signals are supplied to the electronic circuits and the results are stored, interpolated and processed and also compared, to determine the unknown dimension of the measurement interferometer arm. ADVANTAGE - Facilitates interferometric distance measurement.