Wavelength Phase-shifting Interferometry Technology Research

In phase-shifting interferometry, the hardware phase-shifting by PiezoelectricTransducer Device is widely used in optical testing. While testing the large-aperture opticalcomponents, the phase-shifting by Piezoelectric Transducer Device is in difficulties, thenonlinear error is introduced, and it will affects the accuracy of the phase measurement.Phase-shifting interferometry by wavelength tuning avoids the shortcomings of thehardware phase-shifting, this technology shifts the phase by tuning the output wavelengthinstead of driving Piezoelectric Transducer Device, and it is of great value for measuringthe large optical components.In the dissertation, the theory and usual methods for phase-shifting interferometry arepresented. The tuning mechanism of Tunable Diode Lasers is described. The fundamentalprinciple of phase-shifting interferometry by wavelength tuning is analyzed, and thedevelopment is also introduced. Based on the phase-shifting algorithm and the principle ofwavelength tuning, 3-flame algorithm, 4-flame algorithm, average 4-flame algorithm andoverlapping average 4-flame algorithm for phase-shifting by wavelength tuning aresimulated. The main work of the simulation is summarized as follows: interferogramsimulating, phase-shifting algorithm, phase unwrapping and so on. By changing the cavitylength and the wavelength drift, it is demonstrated that the VORTEX Laser guarantees theaccuracy ofλ/100 while the wavelength drift error is less than 2％. In the end of thisdissertation, with the set-up of the phase-shifting interferometry by wavelength tuning, theinterferograms are captured and the profile of the test surface is obtained by theoverlapping average 4-flame algorithm. The experimental results show that thephase-shifting interferometry by wavelength tuning is feasible and effective.