REFRACTIVE ANGLE MEASURING METHOD AND APPARATUS FOR MEASURING DISTRIBUTION OF REFRACTIVE INDEX

摘要

PURPOSE:To detect a refractive angle highly accurately, by splitting light which is transmitted through a cylindrical transparent body at a side surface into two directions, and detecting the positions of the light paths of the bifurcated lights. CONSTITUTION:Matching oil 4 has the approximately equal refractive index as that of the clad part of optical fiber. The side of a base material 3 of the optical fiber which is held in a matching cell 5 is scanned with laser light through the matching oil 4. The transmitted light through the base material 3 is split into the two directions through a light splitter 21. The split lights are inputted into light beam position detectors 22a and 22b such as CCD line sensors which are arranged at positions in such a way that distances QRa and QRb between the splitter 21 and the positions are different. When a refractive angle is 0, the split light beams are inputted at positions Ra and Rb of sensors 22a and 22b. The refractive angle theta can be obtained highly accurately based on difference RaRa' and RbRb' between said position Ra and Rb and positions Ra' and Rb' where the transmitted light beams are inputted. Since the refractive angle can be measured without changing the relative positions of the body to be checked and the optical system for detecting the refractive angle, a moving mechanism for the body to be checked is not required.