Subaperture method for aspheric surface metrology using curvature data

Lee, Seong-Won; Jeon, WooKyung; Park, Taejin; Kim, ByoungChang; Kim, Geon-Hee; Hyun, Sangwon; Kim, IJong; Kim, Seung Hyun; Kim, ChangKyu; Lee, HyungSuk

doi:10.1117/12.2227961

Cited by 1 publication

(1 citation statement)

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“…The curvatures thus obtained are arranged in a determinant according to the position of the sub-apertures and replaced by the gradient matrix at each point through the curvature-slope relation such as Frenet's equation. Finally, the wavefront estimation is performed using the Southwell or Simpson method based on the obtained gradient matrix, 3D surface profile can be reconstructed through the entire clear aperture 4 .…”

Section: Sub-aperture Stitching Interferometry Principlesmentioning

confidence: 99%

High precision interferometric measurement of freeform surfaces from the well-defined sub--aperture surface profiles

Hyun¹,

Je²,

Kim³

2022

Asian Society for Precision Engineering and Nanotechnology (ASPEN 2022)

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We report an interferometric method for smooth freeform optics from the amount of sub-aperture surface profiles. The overall experimental system is composed of a 5-axis precision stage and a sub-aperture measuring interferometer, which is carefully calibrated to achieve 2 nmRMS precision. The sub-aperture interferometer adopts a broadband source in order to maximize the reliability of profile measurement, and a preliminary assumption of the overall surface is derived from the measured local 2nd derivatives which is robust to tip/tilt alignment errors during the sub-aperture acquisition. The optical surface of a 200 mm diameter 2D polynomial freeform mirror is measured based on this system and traditional contact surface profiler for the cross-validation. The experiment shows the effectiveness of the system that the mismatch against a commercial interferometer is less than 20 nmRMS.

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Section: Sub-aperture Stitching Interferometry Principlesmentioning

confidence: 99%