获得等和线的一种简易方法

本文提出在激光全息光弹性方法实验中获得等和线的一种简易方法。文中把一般全息光弹性仪的光路作了改进。把物光光路排列成类似普通光弹性仪的光路。在这个光路中来自分光镜的圆偏振光依次通过扩束镜,准直镜,模型,退偏振漫射器、四分之一波片和线偏振器,最后到达全息干版作为物光。参考光也来自分光镜,在分光镜处它与物光是同旋的圆偏振光。按照这样排列光路,不管模型上是否加有载荷,当用激光全息的单曝光全息图再现时,只能看到模型的像而看不到干涉条纹。如果用两次曝光全息光弹性法所得到的全息图再现,一次曝光是模型上未加载荷,另一次曝光是模型上受有载荷,这时能看到干涉条纹。如果由于受载而模型的厚度发生变化,这时的干涉条纹就是等和线。 文中用琼斯运算作了分析,并且给出径向受压圆环的实验结果。

A Simple Method of Obtaining Isopachics

This paper presents a simple method of obtaining the isopachics in laser holographic photoelasticity. The optical arrangement of general holographic polariscope is improved. The arrangement of the optical elements for the light beam which travels through the model is similar to that of a transmission polariscope. In the optical device, the object beam is a beam of light which comes from the beam splitter, then it passes through the beam spreader, the collimating lens, the model, the depolarizing diffuser, the quarter-wave plate, and the linear polarizer in order and finally arrives at the holographic plate. The reference beam comes from the beam splitter too. And ia the location of the beam splitter, it is the same circularly polarized light as the object beam is. According to the arrangement, when the hologram formed with the single-exposure holography is reconstructed, only the image of the model is seen, but the interference pattern cannot be seen whether the model is loaded or not. If the hologram is reconstructed and formed by the method of the double-exposure holographic photoelasticity, i.e, one exposure is made with the model unloaded and the other made after the model has been loaded, the interference pattern can be seen. If the thickness variation of the model occurs due to loading, the interference pattern is exactly the isopachics.The analysis using the Jones calculus and the experimental results for a circular ring in diametral compression are presented.