Diode Laser Interferometer for Traceable Absolute Distance Measurement

摘要

We present a diode laser interferometer that can measure absolute distances with a few ten micrometer resolution. The light of an external cavity diode laser in Littrow configuration is coupled into a Michelson interferometer and an optical resonator, simultaneously. The interferometer phase and the signal transmitted through the resonator were detected while the wavelength is tuned linearly. The phase difference detected between two transmission peaks of the resonator, divided by π, is equal to the ratio of the interferometer path difference and the resonator length. In particular this ratio is independent of the laser wavelength used. Without wavelength modulation the interferometer can be used as a standard displacement interferometer with a few ten nanometer resolution. The performance of the interferometer is demonstrated on a linear displacement unit of 300 mm length.