Synchronous Demodulation of Pixelated Carrier Frequency Interferograms With the Butterworth Low-Pass Filter

To achieve single-frame dynamic phase measurement, an error-free synchronous demodulation algorithm for two-dimensional pixelated spatial carrier interferograms based on the Butterworth low-pass filter is proposed. It can obtain relatively accurate phase distribution with only one interferograms and is suitable for different noises level. Initially, pixelated spatial carrier interferograms is constructed, and specifically designed complex reference wavefront is introduced to separate the low-frequency phase signal of interest from high-frequency components. Subsequently, the Butterworth filter with specific order is designed for precise low-pass filtering, enabling error-free wavefront phase extraction. Finally, the proposed algorithm is compared with the interpolated 4-step phase-shifting algorithm (I-4PSA). Simulation and experiments demonstrate that the proposed method achieves higher accuracy, functions as global algorithm that is insensitive to noise and phase-shift errors, and effectively avoids the resolution loss and detuning error.