Patent ID: 7164481
Filing Date: 2007-01-16
Classification: G01N

Abstract:
1. A coefficient of linear expansion measuring apparatus comprising: two reflection plates between which a sample is put, a container to house the sample and the reflection plates, the container being filled with a gas having known rate of a refractive index variation, a temperature regulating member to set a temperature inside the container variably, a single light source to irradiate an irradiating light having a known wavelength to reflecting surfaces of the reflection plates placed in the container, a light receiving element to receive an reflected lights reflected on the reflection plates in a condition that the reflected lights interferes each other and to detect a light intensity of the reflected lights, and a calculating member to calculate a coefficient of linear expansion of the sample, wherein: the calculating member calculates an optical path length variation between the reflecting surfaces of the individual reflection plates from an output variation of the light receiving element according to temperature variation in the container, and the calculating member calculates a length variation of the sample by correcting a part of the optical path length variation derived from a refractive index variation of the gas in the container caused by the temperature variation.