基于等光程法测量固体线膨胀系数装置的设计

摘要

基于迈克尔逊干涉仪能够测量微小长度变化量的原理，自行改装并设计出利用等光程法实现对固体材料线膨胀系数精确测量的装置。基本思路是将原迈克尔逊干涉仪上的两个反射镜都改装成动镜，并将改装后的一动镜放在新增的导轨上，然后将其和待测金属棒的一端相连接，当金属棒受热后会产生细微的伸长，进而顶着动镜产生细微的移动，通过调节并观测受热前后屏上干涉条纹“缩进”和“涌出”的分界点来确定金属棒产生的微小形变量，然后根据公式计算出待测金属棒的线膨胀系数。该测量方法克服了传统数条纹方式的缺陷，可实现对金属棒线膨胀系数的精确测量，具有操作简便，实用性强的优点。%Based on the principle that the Michelson interferometer can be used to measure the slight variation in length, a device for accurate measurement of thermal expansion coefficient of solid material line by using the method of equal optical path is revised and designed. The basic idea is that two pieces of mirror on original Michel⁃son interferometer are converted into moving mirror, are put on the new added rail, and are connected with one end of the tested metal rod. When the metal rod is heated, it will lengthen slightly, which drives the moving mirror to pro⁃duce a slight movement. By adjusting and observing the demarcation point of the interference fringes ’“indenta⁃tion”and“emission”on the observation screen before and after heating, the micro change of the shape of the metal rod can be determined. And then, the coefficient of linear thermal expansion of the tested metal rod is calculated ac⁃cording to the formula. The method overcomes the defects of traditional fringe method, and can realize the accurate measurement of the coefficient of linear thermal expansion of the metal rods. This method has the advantages of sim⁃ple in operation and practical.