Double light beam laser interferometry method of material thermal expansion coefficient

Abstract

A two beam laser interference measuring method to measure thermal material expansion coefficient relates to two beam laser interference measuring for thermal material expansion coefficient. A tested sample is positioned into a fastener of a highly vacuum heating furnace and the heating furnace is vacuumized below 10^-4Pa. A laser emitting box of a SIOS-SP120D laser interference instrument emits two beams of laser onto a surface of the tested sample, thus making the lasers reflected to respectively return to a laser emitting port along an original path through the sample surface and forming interference with incident laser. Laser path displacement of the laser beam a and b respectively achieves Delta a and Delta b according to measuring. Expansion of the tested sample in section L is Delta L according to a difference between Delta a and Delta b. A K type thermocouple measures temperature of the tested sampled in the highly vacuum heating furnace. Temperature data will be collected through a data collection data. The thermal expansion of the tested sample of the present invention is a difference of laser path displacement between two laser beams totally offset system errors of single-beam laser resulting from thermal expansion of sampling table and clamp, etc. Therefore, the method completely eliminates system errors while measuring the thermal expansion, improves measuring precision and accurately reflects process of material phase variation.

Description

technical field [0001] The invention relates to the field of thermal expansion measurement of materials, and in particular provides a double-beam laser interferometric method for thermal expansion coefficient of materials. Background technique [0002] The coefficient of thermal expansion is one of the important parameters in the physical properties of materials, and the determination of the coefficient of thermal expansion of solids has important practical significance. The difficulty in measuring the coefficient of thermal expansion is how to accurately determine the change in length of a solid as the temperature changes. At present, the equipment for measuring the thermal expansion of materials mainly includes the single-beam laser interferometry dilatometer based on the basic principle of Michelson interferometry and the dilatometer using the sensor displacement induction method. [0003] The Michelson thermal expansion interferometer is a precision optical instrument t...

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Problems solved by technology

Although this measurement method can obtain high precision at present, due to the interaction force between the quartz rod and the sample, it is difficult to measure samples with high temper

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