Abstract

Minimum deviation of the prism and autocollimation technique was used to measure the refractive index of IR material. Improvements to the measuring method were made by using (1) monochromatic light such as a laser to measure the apex angle and (2) surface coating on one side of a prism instead of a prism mounting to a mirror. These improvements increase the accuracy of the measurement to four significant figures. If the slit is narrowed, better accuracy, i.e., to five significant figures, can be achieved.

© 1987 Optical Society of America