In this paper a method for measuring the refractive index of optical glass automatically is introduced. By this method the refractive index in a wide range ultraviolet

visible and infrared can be measured automatically. When the light source is stable

the accuracy of measurement in visible range can reach?3?10

-6

. This method is based on the principle of minimum deviation angle. The exact position of the minimum deviation angle is traced by a detector guided by outside refrection image. Then the refractive index of sample can be given. In the measurement system

the automatic control

data collection and meesuring process are totally completed by a microcomputer. This method can be also used to measure angle automatically.