Improvement of optical setup of the novel 2D single-shot comb-based interferometer for high-resolution measurement ☆

The novel 2D single-shot comb-based interferometer introduces a massive potential for inline inspection in the industrial chain. The system's advantages are based on a novel optical setup, which combines a new customized infrared pseudo comb light source with a reflected blaze grating acting as a spatial phase modulator. The optical comb source with multiple comb order introduces the system's fantastic ability to extend the measurement range far from the traditional interferometers. At the same time, the grating modulates the incident light into a 2D reference with a delaying optical path difference to provide a real-time profilometry and tomography ability. This research analyzes the optical design to optimize the specifications of the grating and optical imaging lens. Optimized the optics specification improves the profilometry resolution up to the micrometer scale, which was considered impossible in the previous system. Additionally, using the unique infrared pseudo frequency sweeping laser as the comb source, the system minimizes the natural speckle-noise effect from the optics, which is the barrier of all typically visible measurement systems. The experiment was successfully conducted to calibrate the new specifications of the system, followed by the experiment measuring the only 1μm displacement of the mirror to discover the profilometry resolution improvement. The system's ability to measure the scattering sample is also investigated by the experiment inspecting the profile of a Japanese 10-yen coin. The research proves the 2D single-shot comb-based interferometer as one of the most powerful optical devices for industrial inline inspection.