Abstract:
Because of its high dynamic range and high accuracy, two-wavelength interferometry has great potential, but there are some problems with the use of piezoelectric phase shifting technology, compared with the conventional piezoelectric phase shifting technology, in full-field heterodyne phase shifting technology, the heterodyne light source with low frequency difference can easily realize multi-step phase shifting algorithm, simplify the procedure of phase shifting, ensure the phase shifting accuracy of different wavelengths at the same time. A full-field heterodyne two wavelength phase shifting interferometry is proposed and a full-field heterodyne two wavelength phase shifting interferometer system is built, an aspheric mirror with maximum deviation of 13 μm at the edge and a step with a height of (1.3±0.1) μm is tested. With some experiment tests, the PV error is
λ/3.53 at 633 nm wavelength, the PV repeatability is
λ/77.38, the RMS error is
λ/14.16, the RMS repeatability is
λ/919.10 when testing the aspheric mirror and the height error is
λ/16.19, the height repeatability is
λ/311.85 when testing the step.