Measurement of the chromatic dispersion of gradient index materials by multiple wavelength A.C. interferometry

Thesis (M.S.)--University of Rochester. College of Engineering and Applied Science. Institute of Optics. This thesis was digitized by the Institute of Optics in 2014 and was determined to have lapsed into the public domain. If you are the author and have questions about the digitization of your work, please contact Kari Brick, Graduate Program Coordinator for the Institute of Optics, at kbrick@ur.rochester.edu. Other contact information for the Institute is available at http://www.optics.rochester.eduThe effects of the dispersion in homogeneous glass on the quality of lenses are known. In many cases these color related effects limit the performance of an optical lens. Gradient index materials offer a means to improve the performance of a lens in both monochromatic and polychromatic applications. For these materials to be incorporated into a lens design, accurate knowledge of the index of refraction profile and the dispersion of the gradient are necessary. Multiple wavelength a.c. interferometry has been investigated as a method of measurement to obtain both the index of refraction and the dispersion as a function of spatial coordinates. The theory for multiple wavelength a.c. interferometry has been developed. Computer programs have been written which predict the amplitude of the a.c. signal (a measure of the dispersion) and calculate the dispersion of the gradient from the amplitude of the a.c. signal. An a.c. Mach Zehnder interferometer has been built to measure the index of refraction profile and the chromatic dispersion of the gradient. Optical signals for single wavelength and multiple wavelength irradiance patterns are obtained simultaneously to eliminate registration errors of the spatial coordinates. The optical signals are processed electronically to yield the index of refraction profile and the amplitude of the a.c. signal. The system is interfaced to a computer to eliminate problems associated with handling of data. Programs have been written which yield the index of refraction at one wavelength and the dispersion of the gradient as a function of spatial coordinates. The measurements confirm the validity of the theory of multiple wavelength a.c. interferometry for measuring the dispersion of gradient index materials