Confocal microscope method for curvature radius measurement of small lens

Qian Liu; Weichuan Yang; Pengyue Wu; Daocheng Yuan

doi:10.1117/12.966325

15 October 2012 Confocal microscope method for curvature radius measurement of small lens

Qian Liu, Weichuan Yang, Pengyue Wu, Daocheng Yuan

Proceedings Volume 8417, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment; 841706 (2012) https://doi.org/10.1117/12.966325
Event: 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT 2012), 2012, Xiamen, China

Abstract

With the minimization of optical devices, the size of lens becomes much smaller. As a crucial parameter of spherical lens, the measurement of curvature radius is valuable in small lens manufacturing. In this paper, confocal microscope method is proposed to measure curvature radius of spherical lens, especially small spherical lens. The setup of this method consists of a confocal microscope and a grating bar. The detector of confocal microscope gives maximum output when the spherical surface is placed at “cat’s eye” position or confocal position. The distance between cat’s eye and confocal position is the curvature radius of spherical surface. This method is suitable for both concave and convex surface. The response of detector to axial and traversal displacement is analyzed and simulated. And the measurement error is estimated with the simulated results. The setup employed a 10x microscope objective of 0.2 NA and pinhole of 0.04mm diameter, and experiment was conducted to measure the radius of a standard optical ball of 3mm diameter. The error of result is less than 0.01mm. It’s concluded that the error could be reduced less than 0.001mm with higher numerical aperture and more precise movement stages.

Citation Download Citation

Qian Liu, Weichuan Yang, Pengyue Wu, and Daocheng Yuan "Confocal microscope method for curvature radius measurement of small lens", Proc. SPIE 8417, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 841706 (15 October 2012); https://doi.org/10.1117/12.966325

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