Measurement of gradient index profile using deflectometry

The present paper reports a simple technique for measurement of one dimensional graded index (GRIN) profile using deflectometry. In this method the linear fringe pattern generated by a lateral shear interferometer using a Wollaston prism is made incident on the GRIN sample and the profile is measured from the deflection of the fringes. The method is simple and also gives a visual display of the GRIN profiles. Computation of the profile from the deflection of fringes is also simple. Measured data is compared with the theoretical ones obtained from the solution of the diffusion equation. Results are reported for negative refractive index profiles made by exchanging Na+ for Li+ ions in Na2O–Li2O–Al2O3–ZrO2–SiO2 glasses.