Wavelength-tuning point diffraction interferometer resisting inconsistent light intensity and environmental vibration: application to high-precision measurement of a large-aperture spherical surface

Phase-shifting point diffraction interferometers are used to measure large-aperture spherical optical elements because of their high level of measurement accuracy. As the most commonly used phase-shifting method, piezoelectric ceramic transducers are faced with nonlinear problems. Wavelength tuning is typically used to solve the phase-shifting problem; however, it is sensitive to environmental vibrations and light intensity changes during tuning. Therefore, a global optimization iterative algorithm based on interferogram normalization is proposed here. The method is insensitive to noise, defects, and light intensity changes and has a strong ability to resist environmental disturbance. Simulations and experiments are performed to verify the effectiveness of the proposed method. (C) 2019 Optical Society of America