Periodic error is the major problem that limits the accuracy of heterodyne interferometry. A traceable system for periodic error measurement is developed based on a nonlinearity free Fabry-Perot (F-P) interferometer. The displacement accuracy of the F-P interferometer is 0.49 pm at 80 ms averaging time, with the measurement results referenced to an optical frequency comb. Experimental comparison between the F-P interferometer and a commercial heterodyne interferometer is carried out and it shows that the first harmonic periodic error dominates in the commercial heterodyne interferometer with an error amplitude of 4.64 nm.
Note: Periodic error measurement in heterodyne interferometers using a subpicometer accuracy Fabry-Perot interferometer
Minhao Zhu, Haoyun Wei, Xuejian Wu, Yan Li; Note: Periodic error measurement in heterodyne interferometers using a subpicometer accuracy Fabry-Perot interferometer. Rev. Sci. Instrum. 1 August 2014; 85 (8): 086102. https://doi.org/10.1063/1.4891696
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