基于几何光学原理,彩虹法使用激光作为光源,利用激光在玻璃微珠中进行一次或者多次内反射后出射形成最小偏向角,在最小偏向角附近形成彩虹条纹,通过测量彩虹条纹来反演计算玻璃微珠的折射率。然而,成像法则根据厚透镜的成像原理,对玻璃微珠所成的像经过显微物镜放大后使用CCD相机进行接收,获得玻璃微珠的焦距,进而测得对应玻璃微珠的折射率。较传统方法来说,彩虹法和成像法具有安全、简便和快捷的优点。对型号不同的玻璃微珠,分别使用彩虹法和成像法测量其折射率,并对它们的测量结果进行了对比分析,都获得相对于名义值的误差小于1%的结果。

On the basis of the principle of geometrical optics, using a laser as light source in the experiment of the rainbow method, the emerging rays form the minimum deviation angle after the laser in glass beads for one or more times internal refraction. Near the minimum deviation angle, it appears the rainbow fringes. By measuring the rainbow fringes, it can calculate the refractive index of glass beads. According to the imaging principle of the thick lens, the experiment of imaging method uses CCD camera to receive the image after the microscope objective amplified the glass beads imaging in order to get the focal length of glass beads, then it can measure the refractive index of glass beads. The two methods are safer, easier and faster than traditional ones. For the different types of glass beads, though analyzed and compared with the experimental results of the two methods, it is obtained that the error between the experimental results and the nominal value is less than 1%.