- Measurement Principle
To measure the birefringence of large blocks (including disks and sheets), the optical system is divided into two parts, and the sample stage is placed between the two parts. For example, the following configuration can be considered. This figure shows the basic configuration when measuring the optical glass of an elliptical disk. A light source and a half-wavelength plate are placed on the other side of the sample, and a linear polarizer and a photodetector are placed on this side. The stage on which the disk is placed is an automated stage capable of two-dimensional scanning (scanning range 800 x 800 mm).
The following figure shows the result of the measurement of the disk. 