Interferometric device for measurement of variations in length of a sample under the influence of temperature

摘要

An interferometric device is provided for measurement of the variations in length of a sample under the influence of temperature, the length of the sample being within a plane of reference and a plane of measurement defined by two plane terminal faces of the sample. The device comprises a source of monochromatic light, means to form parallel beams from the light source, a controllable temperature thermostatic enclosure containing a sample holder, a reflecting measurement surface joined to the plane of measurement for receiving one of the beams, a reflecting reference surface for receiving the other beam, a bearing face presented by the sample holder for the terminal reference face of the sample which is elastically applied against the bearing face, and support means for supporting the reflecting reference surface inside the enclosure and ensuring that the variation of distance between the two reflecting surfaces will always be equal to the variation in length of the sample when the temperature of the thermostatic enclosure is varied. The two beams reflected respectively by the two reflecting surfaces are caused to interfere, and a sensor observes and measures interference fringes.