Measuring the refractive index of transparent materials using high precision circular heterodyne interferometry

This study measured a wide range of the refractive index of transparent glass with low phase error using precision circular heterodyne interferometry. We determined precision measurement conditions with theoretical error analysis. The findings showed that minimum phase error could be achieved through appropriate selections of the incident angle and azimuth angle of the analyzer. Using the proposed method, phase error could be estimated at better than 1 x 10(-4). Error in refractive index measurements for each sample could be estimated at better than 1 x 10(-4) under precision measurement conditions. In addition, the proposed method has the advantages of simple optical configuration, easy operation, and a wide measurement range of the refractive index of transparent materials. (C) 2012 Elsevier Ltd. All rights reserved.