title: Single-shot 3 × 3 beam grating interferometry for self-imaging free extended range wave front sensing.
abstract: Crossed grating 3×3 beam lateral shear interferometry for extended range wave front sensing is presented. A Fresnel diffraction pattern of two multiplicatively superimposed linear diffraction gratings each generating three diffraction orders is recorded. A simple solution employs a common crossed binary amplitude Ronchi grating with spatial filtering. Digital processing of a single-shot pattern includes separating multidirectional pairs of orthogonal lateral shear interferograms, retrieving second harmonics of their intensity distribution, and calculating shearing phases. Single-frame automatic fringe pattern processing based on the Hilbert-Huang transform is used for this purpose. Using second harmonics extends the aberration measurement range since they encode self-imaging free two-beam interferograms without contrast modulations. Experimental works corroborate the principle and capabilities of the proposed approach.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Patorski
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Służewski
authors.forename: Maciej
authors.initials: M
authors.lastname: Trusiak