High-resolution detection of small distance changes by an optical frequency comb

The work presents a measurement of lengths by an optical measuring resonator. The resonator works as distance-to-optical frequency converter with ultimate linearity. It has locked a tunable laser to certain cavity mode. The optical frequency of the laser is heterodyned with immediate "tooth" of the femtosecond comb spectrum. For the testing of the method the special combination of the optical resonator and Michelson interferometer was put together. This system combines the cavity length of the optical resonator with the measuring arm of the Michelson laser interferometer. The one mirror of the system is common for both laser interferometers and it is driven by piezoelectric transducer. The testing range is limited by the range of tuneability of the used laser and it covers 1000 nm of the length measurement.