Opto-Electronic Engineering, Volume. 52, Issue 7, 250059(2025)

Measurement of high reflectivity uniformity of curved mirrors based on cavity ring-down technique

Haihong Cai1, Bincheng Li1,2、*, Yanling Han1,3, Jing Wang1,2, and Hao Cui1,2
Author Affiliations
  • 1School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, China
  • 2State Key Laboratory of Adaptive Optics, Chengdu, Sichuan 610209, China
  • 3Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, Sichuan 610209, China
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    A measurement method for mapping the reflectivity distribution of curved high-reflectivity mirrors based on optical feedback cavity ring-down (OF-CRD) technique is introduced. The setup consists of a high-stability folded optical cavity and a high-precision positioning system with 5 degrees of freedom (DOF). By mathematical modeling, we established a universal mathematical relationship between the curved surface described by mathematical formula and the required adjustment for sample positioning, enabling dynamic five-dimensional compensation for optical elements with varying curvatures, apertures, and surface profiles. Through high-precision automated scanning strategy, the high-reflectivity distributions of samples with different surface profiles, apertures, and curvature diameters are obtained, this measurement is achieved by two-dimensionally raster-scanning while compensating for the other three dimensions (depth, pitch, and yaw) of the samples using a control program to ensure strict normal alignment between the probe beam and local surface throughout the measurement process. A reflectivity measurement repeatability error at the part-per-million (ppm) level is experimentally achieved. Good agreement is observed between the CRD-measured reflectivity profile and the grayscale image obtained by a laser confocal microscopy. Compared with the reflectivity values obtained by manual high-precision alignment, both reflectivity distributions obtained via automatic and manual alignments are consistent, demonstrating the reliability of the reflectivity distribution obtained with the experimental apparatus.

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    Haihong Cai, Bincheng Li, Yanling Han, Jing Wang, Hao Cui. Measurement of high reflectivity uniformity of curved mirrors based on cavity ring-down technique[J]. Opto-Electronic Engineering, 2025, 52(7): 250059

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    Paper Information

    Category: Article

    Received: Feb. 28, 2025

    Accepted: May. 8, 2025

    Published Online: Sep. 4, 2025

    The Author Email: Bincheng Li (李斌成)

    DOI:10.12086/oee.2025.250059

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