再回折光学系を用いた物体の位相分布の測定

(I) 回折面上のmaskの移動による方法

抄録

A new method of measuring the optical phase distribution in materials based on the accom-panying double diffraction has been developed. Several methods of filtering the Fraunhofer diffrac-tion plane are considered.
In Part 1, a method with a sharp cut-off amplitude filter is described; the phase distribution in a specimen is obtained by observing the contours of image pattern corresponding to the position of the edge of the mask that scans the diffraction plane of the optical system.
As a practical application of this method, strain distribution in a plate under concentrated load is determined with good accuracy; the region measured is wider by this method than by conventional interference methods. Use of the photoelastic method at the same time makes the numerical analyses of stress and strain distributions possible with very small errors. The application of immersion or reflection method can discriminate the effect due to variation of refractive index from the effect due to variation of thickness. This would therefore enable easy determina-tion of the distribution of principal refractive indices of strained materials or the waviness of metal surface.