title: Laser differential reflection-confocal focal-length measurement.
abstract: A new laser differential reflection-confocal focal-length measurement (DRCFM) method is proposed for the high-accuracy measurement of the lens focal length. DRCFM uses weak light reflected from the lens last surface to determine the vertex position of this surface. Differential confocal technology is then used to identify precisely the lens focus and vertex of the lens last surface, thereby enabling the precise measurement of the lens focal length. Compared with existing measurement methods, DRCFM has high accuracy and strong anti-interference capability. Theoretical analyses and experimental results indicate that the DRCFM relative measurement error is less than 10 ppm.
authors.affiliation: Key Laboratory of Photoelectronic Imaging Technology and System, Ministry of Education of China, Opto-Electronic College, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Jiamiao
authors.initials: J
authors.lastname: Yang
authors.forename: Lirong
authors.initials: L
authors.lastname: Qiu
authors.forename: Weiqian
authors.initials: W
authors.lastname: Zhao
authors.forename: Hualing
authors.initials: H
authors.lastname: Wu