Abstract

A new heterodyne technique for the quantitative analysis of schlieren images is described. The technique is based on phase measurements of signals generated by a photodetector observing the variations in light intensity caused by a traveling grating of slits located at the knife-edge plane of a conventional schlieren system. The phase of the signal is proportional to the displacement of the slit image on the knife-edge plane as a result of the light deflection passing through a phase object. The displacement is proportional to the ray deflection angle and hence to the local gradient of the index of refraction. The technique, which is quantitatively precise and sensitive, is demonstrated by measurement of deflections caused by a lens with a focal length of $f=20 \mathrm{m}$. A displacement of 0.22 mm and a deflection of an angle of $5.2\times {10}^{-4} \mathrm{rad}$ were detected.

© 2003 Optical Society of America

Full-field optical coherence tomography by two-dimensional heterodyne detection with a pair of CCD cameras

M. Akiba, K. P. Chan, and N. Tanno
Opt. Lett. 28(10) 816-818 (2003)

Knife-Edge Controller for a Schlieren System

C. B. Wells
Appl. Opt. 4(7) 815-818 (1965)

Compact color schlieren optical system

Donald R. Buchele and DeVon W. Griffin
Appl. Opt. 32(22) 4218-4222 (1993)

High spatial resolution schlieren photography

J. W. Hosch and J. P. Walters
Appl. Opt. 16(2) 473-482 (1977)

Phase-shifting schlieren: high-resolution quantitative schlieren that uses the phase-shifting technique principle

Luc Joannes, Frank Dubois, and Jean-Claude Legros
Appl. Opt. 42(25) 5046-5053 (2003)