Measuring the lens focal length by laser reflection-confocal technology.

TitleMeasuring the lens focal length by laser reflection-confocal technology.
Publication TypeJournal Article
Year of Publication2013
AuthorsYang J, Qiu L, Zhao W, Shao R, Li Z
JournalApplied optics
Volume52
Issue16
Pagination3812-7
Date Published2013 Jun 1
Abstract

A laser reflection-confocal focal-length measurement (LRCFM) is proposed for the high-accuracy measurement of lens focal length. LRCFM uses the peak points of confocal response curves to precisely identify the lens focus and vertex of the lens last surface. LRCFM then accurately measures the distance between the two positions to determine the lens focal length. LRCFM uses conic fitting, which significantly enhances measurement accuracy by inhibiting the influence of environmental disturbance and system noise on the measurement results. The experimental results indicate that LRCFM has a relative expanded uncertainty of less than 0.0015%. Compared with existing measurement methods, LRCFM has high accuracy and a concise structure. Thus, LRCFM is a feasible method for high-accuracy focal-length measurements.

DOI10.1186/2193-1801-2-276
Alternate JournalAppl Opt