Optical deflectometry, likewise many other optical methods, permits to reconstruct the wavefront deformations induced by a refractive or a phase object. In this paper, a Fourier based deflectometry method is presented. A telecentric imaging system acquires pictures of a grating being the superposition of two crossed Ronchi rulings of the same spatial frequency. The object under test is inserted in the optical path between the grating and the telecentric imaging system. The presented Fourier based image analysis permits to extract the wavefront derivatives, and therefore permits to reconstruct the wavefront or the local power of the object. In this paper, the method is illustrated on several free form thermoplasic elements, the sensitivity is determined experimentally, the precision is analyzed and the ability to characterize cosmetic defects is evaluated.

Date Published: 17 June 2009
PDF: 12 pages
Proc. SPIE 7389, Optical Measurement Systems for Industrial Inspection VI, 73890M (17 June 2009); doi: 10.1117/12.827670

Published in SPIE Proceedings Vol. 7389:
Optical Measurement Systems for Industrial Inspection VI
Peter H. Lehmann, Editor(s)