A method using two-windows common-path interferometry with phase grating is presented to measure the curvature radius (CR). This interferometry is built using a 4f optical system with binary phase grating implemented by spatial light modulator (SLM) as spatial filter. The input plane is formed by two windows, which are used for the measured lens and reference beam, respectively. In the output plane, an interferogram can be achieved by a proper choice of the windows’ spacing with respect to the grating period. The phase of the lens can be retrieved from the shift phase of composite interferograms achieved by lateral movements of the grating. The curvature radius of the lens is thus directly derived from the phase function. A theoretical model is also established using Fourier transform theory and phase retrieval algorithm to describe the measured process using phase-shifting interferometry. Analyzed results indicate that the method is an effective approach for the radius measurement with inherent simplicity, high robustness and flexibility.

Date Published: 31 January 2013
PDF: 5 pages
Proc. SPIE 8759, Eighth International Symposium on Precision Engineering Measurement and Instrumentation, 87591X (31 January 2013); doi: 10.1117/12.2012499

Published in SPIE Proceedings Vol. 8759:
Eighth International Symposium on Precision Engineering Measurement and Instrumentation
Jie Lin, Editor(s)