Interferometric Measurement Of The Optical Refractive Index

The refractive index is one of the fundamental parameters of the optical glasses, for the high-quality optical system, the refractive indices of the optical glasses must be tested accurately. With the development of optical fiber, medicine, new crystal, infrared optics, environmental protection and so on, the conventional methods are difficult to, sometimes unable to, meet the requirement, so it's always the important task to develop new measuring method to meet the new requirement.The interference method for determination of refractive index has many advantages, such as easy-producing sample, extensive testing range, and the reutilization of sample. Besides these, it can realize the test of refractive index and the use of the optical system in the same equipment, which is helpful to improve the assurance of the optical system, especially to some special system, for example the compensator for the null test of large-diameter primary.Based on reviewing of existed method, the interferential measure is presented, principle is given, formula is deduced, and factors affecting the testing result are analyzed. Then the experimental setup and the program written in Matlab for data collecting and processing, are introduced. In order to get around the shortcoming,the sample thickness is tested accurately, of existed interferential method,a new algorithm is put forward. In comparison with the angle of minimum deviation, the errors are analyzed and the correcting method for the temperature affect is given.