US 12,305,976 B2
Optical system using enhanced static fringe capture
Curtis Blake LaPlante, Ottawa (CA); Bruno Machado Trindade, Kanata (CA); and Eranga Madujith Ukwatta, Toronto (CA)
Appl. No. 17/999,859
Filed by BMV Optical Technologies Inc., Ottawa (CA)
PCT Filed Jun. 14, 2021, PCT No. PCT/CA2021/050804
§ 371(c)(1), (2) Date Nov. 24, 2022,
PCT Pub. No. WO2021/253113, PCT Pub. Date Dec. 23, 2021.
Claims priority of provisional application 63/039,096, filed on Jun. 15, 2020.
Prior Publication US 2023/0213334 A1, Jul. 6, 2023
Int. Cl. G01B 11/30 (2006.01); G01B 9/02 (2022.01); G01B 9/02055 (2022.01); G01B 9/02056 (2022.01)
CPC G01B 11/30 (2013.01) [G01B 9/02049 (2013.01); G01B 9/02056 (2013.01); G01B 9/02072 (2013.04)] 18 Claims
OG exemplary drawing
 
1. An interferometer system comprising:
a light source for providing an input wave with a directional axis;
a beam splitter for splitting the input wave;
a reference surface for receiving the split input wave;
a pivoting mount for releasably engaging the reference surface;
an open loop piezoelectric tilt actuator on the pivoting mount and coupled to the reference surface configured to angularly oscillate the reference surface at a tilt frequency and at a plurality of tilt angles relative to the input wave to provide an angular tilt displacement of the reference surface during image measurement such that the reference surface is at an oscillating non-zero angle of incidence relative to the directional axis of the input wave;
a microcontroller coupled to the tilt actuator for controlling the angular tilt displacement of the tilt actuator;
a detector configured to collect interferometry data from the reference surface comprising a plurality of wavefront measurements; and
a data processing apparatus coupled to the detector for processing interferometry data collected by the detector and overlaying the plurality of wavefront measurements to subtract out short retrace errors for the wavefront measurements for pre-measurement calibration to provide a system background image measurement for the reference surface.