Method and apparatus for measuring photo-elastic constant

Abstract

Abstract PURPOSE:To obtain the highly accurate optical elastic constant of a sample which has residual strain and has only the minimum photo-elastic effect by obtaining the amount of birefringence and the main-axis orientation of birefringence under the state wherein external stress is applied and the state wherein it is not applied, and obtaining those values of a sample under the state wherein the effect of the residual strain is not present and only the external stress is applied. CONSTITUTION:Under the state wherein compressing stress is not applied on a sample 6, a 1/2-wavelength plate 5 and a linear polarizer 8 are rotated at a speed ratio of 1:2. The phase difference signal sent from a phase-difference detecting means 10 is inputted. A sine- variation curve of retardation due to the birefringence of the sample 6 is computed. The amplitude of the sine variation curve is obtained. The rotated angle of the 1/2-wavelength plate is obtained from the time when the rotary angle of the 1/2-wavelength plate is 0 to the time when the sine-variation curve of the retardation indicates the maximum value at first. The amount of the birefringence of the sample 6 and the main-axis orientation of the birefringence when only the residual strain is present are temporarily stored. Then, the amount of the birefringence of the sample 6 and the main-axis orientation of the birefringence are computed under the state wherein compressing stress P is applied on the sample 6, and the values are temporarily stored. The amount of the birefringence of the sample 6 and the main-axis orientation of the birefringence are computed by operating vector based on the computed values.

Inventors

• 👤 Hiroyuki Takawa
• 👤 宏行 高和

Bibliographic Details