This paper describes the development of a fiber-optic confocal probe suitable to measuring the central thickness of highcurvature small-diameter optical ball lenses. The confocal probe utilizes an integrated camera that functions as a realtime apex-sensing device. An additional camera is used to monitor the shape of the reflected light beam. Placing the instrument sensing spot off-center from the apex will produce a non-circular image at the camera plane that closely resembles an ellipse for small displacement. By analyzing the shape of the reflected light spot, we are able to precisely determine the focus point of the confocal probe relative to the apex point to better than 2-μm precision for ball lenses with diameters in the range of 3 – 10 mm. The proposed confocal probe offers a low-cost alternative technique for quality control of ball lenses during the manufacturing process.

Date Published: 20 November 2012
PDF: 7 pages
Proc. SPIE 8563, Optical Metrology and Inspection for Industrial Applications II, 85630M (20 November 2012); doi: 10.1117/12.999967

Published in SPIE Proceedings Vol. 8563:
Optical Metrology and Inspection for Industrial Applications II
Kevin G. Harding; Peisen S. Huang; Toru Yoshizawa, Editor(s)