Research on spatial carrier phase-shifting algorithm and its application in quadri-wave lateral shearing interferometer

In optical systems, the accuracy of the lens is the basis for system performance. To ensure the accuracy of the lens, high-precision detection methods are crucial in lens processing. Commonly used phase-shifting interferometers are susceptible to environmental influences, while the quadriwave lateral shearing interferometer (QWLSI) can solve this problem. QWLSI reconstructs the wavefront from just one interferogram and is becoming increasingly popular owing to its compactness and portability. The most commonly used method to analyze interferograms in QWLSI is the Fourier transform method (FTM), which requires more sophisticated processing and computing time and is erroneous at the edge of the aperture. This study deduces that the spatial carrier phase-shifting (SCPS) algorithm should replace the FTM in QWLSI. Theoretical derivations and simulation results showed that QWLSI works faster and more accurately when the SCPS replaces the FTM.