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Proceedings Paper

Measuring the lens focal length by laser confocal technique
Author(s): Hualing Wu; Jiamiao Yang; Liurong Qiu; Weiqian Zhao
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Paper Abstract

A new laser confocal focal-length measurement (LCFM) is proposed for the high-accuracy measurement of lens back focal length. LCFM uses the peak point of confocal response curve to precisely identify the lens focus, and uses the elastic contact between reflector R and the lens last surface to determine the test lens last vertex. The distance between the reflectors on these two positions is then measured by a laser distance interferometer, and then the accurate back focal-length of test lens is obtained. Compared with existing methods, LCFM significantly improves the measurement accuracy and simplifies the system structure by laser confocal technique, and reduces the product development cost. LCFM is especially suitable for the back focal-length measurement of large aperture lens.

Paper Details

Date Published: 10 October 2013
PDF: 10 pages
Proc. SPIE 8916, Sixth International Symposium on Precision Mechanical Measurements, 89161E (10 October 2013); doi: 10.1117/12.2035803
Show Author Affiliations
Hualing Wu, Beijing Institute of Technology (China)
Jiamiao Yang, Beijing Institute of Technology (China)
Liurong Qiu, Beijing Institute of Technology (China)
Weiqian Zhao, Beijing Institute of Technology (China)


Published in SPIE Proceedings Vol. 8916:
Sixth International Symposium on Precision Mechanical Measurements
Shenghua Ye; Yetai Fei, Editor(s)

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