Measurement of gradient refractive index profile using a birefringent lens

The shape, depth, and maximum change in refractive index profile are of the most important parameters to be controlled when developing gradient refractive index (GRIN) lens blanks. Generally refractive index profiles are measured by standard interferometers such as Mach-Zhender, Twyman, and Shearing interferometers. These methods generate a large amount of data and need rigorous computation. A new kind of deflectometery is reported that can measure a GRIN profile using the interference pattern generated by a birefringent lens. Results based on this method are presented for radial GRIN glasses developed by Ag+-Na+ and Na+-Li+ ion exchange in alkali aluminosilicate glasses. (C) 1996 Society of Photo-Optical Instrumentation Engineers.