Luo Jia, Bai Jian, Zhang Jinchun, Hou Changlun, Wang Kaiwei, Hou Xiyun
Opt Express. 2014 Nov 17;22(23):27921-31. doi: 10.1364/OE.22.027921.
A new accurate method for long focal-length measurement based on Talbot interferometry is proposed. A divergent beam and two Ronchi gratings of different periods are employed, as the alternative of the collimated beam and two identical gratings, to achieve higher measurement accuracy. Moreover, with divergent beam, lenses of large aperture can be easily measured without scanning, which is required when it comes to traditional collimated beam. Numerical analysis and experiments were carried out. The results demonstrate the proposed method features remarkably high accuracy and repeatability.
