一、前言干涉膨胀仪是对固体材料热彩胀系数进行绝对测量的最普通方法。但该方法通常需要对试样进行精细地抛光,因而它的应用受到了限制。例如裴索(Fizeau)法要求来自试样两端的反射光线严格地进行。与此相反、光学外差法对反射光线的平行性要求比别的干涉 I. INTRODUCTION Interference dilatometer is the most common method of absolute measurement of thermal eclipse coefficient of solid material. However, this method usually requires fine polishing of the sample, and thus its application is limited. For example, the Fizeau method requires that the reflected light from both ends of the sample is strictly performed. In contrast, optical heterodyne methods require more interference with the parallelism of reflected light than otherwise