Open AccessVerification of cascade optical coherence tomography for freeform optics form metrology
Author(s) -
Disheng Xu,
Zhenkun Wen,
Andres Garcia Coleto,
Michael Pomerantz,
John C. Lambropoulos,
Jannick P. Rolland
Publication year - 2021
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.413844
Subject(s) - metrology , optics , optical coherence tomography , flatness (cosmology) , cascade , computer science , coherence (philosophical gambling strategy) , adaptive optics , materials science , physics , engineering , cosmology , quantum mechanics , chemical engineering
Freeform optical components enable dramatic advances for optical systems in both performance and packaging. Surface form metrology of manufactured freeform optics remains a challenge and an active area of research. Towards addressing this challenge, we previously reported on a novel architecture, cascade optical coherence tomography (C-OCT), which was validated for its ability of high-precision sag measurement at a given point. Here, we demonstrate freeform surface measurements, enabled by the development of a custom optical-relay-based scanning mechanism and a unique high-speed rotation mechanism. Experimental results on a flat mirror demonstrate an RMS flatness of 14 nm (∼λ/44 at the He-Ne wavelength). Measurement on a freeform mirror is achieved with an RMS residual of 69 nm (∼λ/9). The system-level investigations and validation provide the groundwork for advancing C-OCT as a viable freeform metrology technique.