Device and method for high-accuracy measurement of expansion coefficients of metal wire

Abstract

The invention discloses a device and a method for high-accuracy measurement of expansion coefficients of a metal wire. The method uses a PZT oscillating mirror system to perform frequency modulation on incident light at different times, can not only modulate parameter information to be measured to a phase difference, but also modulate the parameter information to be measured to in a frequency difference for the convenience of later signal treatments; and the device consists of an interference system, a high-speed PZT oscillating mirror system, a heating system and a signal processing system. Comparing the method with other measuring methods, a multi-beam laser heterodyne measuring method for measuring the expansion coefficients of the metal wire has the advantages of high space and time resolutions, high measurement accuracy, high linearity, quick dynamic response, large measuring range and the like, and simultaneously the method has the advantages of simple structure for an experimental apparatus, low power consumption, convenient operation, high repeatability, small experimental result error, high accuracy and the like. Because experimental phenomena are obvious and experimental data is reliable, the method and the device can be widely applied in the fields of engineering designs and the like, and have very high practical values in the field of laser ultra-precision measurements.

Description

A device and method for measuring the linear expansion coefficient of metal with high precision technical field The invention relates to a device and method for measuring the linear expansion coefficient of metal with high precision, in particular to a device and method for measuring the linear expansion coefficient of metal with multi-beam laser heterodyne with high precision. Background technique In daily life and actual production, the change in the length of a solid in one dimension after being heated is usually called linear expansion. Under the same conditions, solids of different materials generally have different degrees of linear expansion. As a characterization of the expansion properties of materials, the linear expansion coefficient is not only an important content in the teaching of physical experiments, but also used in the design of roads, bridges, buildings, precision instruments, meters, etc., as well as in the welding and processing of materials. Very wi...

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Problems solved by technology

In the process of measuring with these methods, because there are too many parameters that need to be directly measured, the operation is more complicated, so that the systematic error and accidental error of the experiment are relatively large. For example, when the optical lever method is used to measure the linear expansion coefficient of metal, due to the The adoption and complex operation make the system error relatively large. At the same time, the accidental error introduced by the unreasonable configuration of the reading device is also relatively large, so that its relative error reaches 4.4%. The system error caused by the actual temperature and the delay of the sensor has greatly limited its measurement accuracy; the laser interferometry has greatly reduced the experimental error due to the sharp interference fringes and high resolution of the device, and the experimental operation is simple at the same time. The precise measurement of the metal linear expansion coefficient has been realized, and the relative error of the measurement can be 2%, but this method has occasional errors caused by vision when reading the number of interference fringes, resulting in no further improvement in accuracy

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