Quantitative Shadow Method For Measuring A One-Dimensional Refractive Index Distribution

A quantitative shadow method was developed and tested by measuring the one-dimensional refractive index distribution of a polished slab of gradient index glass. Tests made on the known glass sample showed that a one-dimensional index distribution can be measured by shadowgraphy to better than 1% accuracy. The method uses simple optics and can easily be auto-mated to perform rapid measurements. Extension of the shadow method to more general distributions requires making many traverses of the refractive index distribution with a narrow sheet of light.