Quadrature-based interferometry using pulsed RGB illumination

This contribution introduces a novel image recording approach for phase retrieval in a RGB-interferometer setup with pulsed LED illumination and an oscillating reference mirror. The effective acquisition time of the interference images is below 100 μs with a repetition rate of 10 frames per second. The pulsed illumination is synchronized with the exposure gap of a Bayer-Pattern CMOS RGB camera to enable the recording of two π/2 phase shifted images with a short delay compared to the camera exposure time. The proposed quadrature method enables surface phase retrieval with a standard deviation of ≈ [3 nm, · · ·, 5 nm], depending on phase noise and actuator precision. The applicability of the reconstructed phase data to unambiguity range extension algorithms based on the exact fraction method is considered. Experimental results demonstrate the feasibility of the setup to measure the topography of samples in motion or oscillating by mechanical vibrations.