Research On Transient Temperature Field Measurement System Based On Multi - Spectral Fitting

In the field of defense, aerospace and scientific research, the commonly used contact and non-contact methods can not simultaneously satisfy the demands of high speed and accuracy of temperature measurement in transient physical fields with unstable factors and high temperature up to thousands (or even hundreds of million degrees) changing rapidly. This artcle aims at developing a system based on multi-spectral to solve those problems above in the measurement of transient temperature field.During measurement, electromagnetic radiation, vibration and other unstable factors on the spot will severely interference the precision testing parts of the system, bringing much uncertainty to the result. In order to solve this problem, this article proposed a design that adopting optical fiber to connect the sampling mechanism and the core measuring module of the system, which realized their separation in physical location. Through reasonable designing for the related parameters of the key components, the target spetrual signal could be transferred efficiently through a long distance, making it posible for the core measuring module of the system to calculate the target temperature in a stable environment off site.Considering that the temperature of the target changes rapidly, photomultipliers with high speed response were utilized as the photodetector of the device which worked together with the high speed conversion circuit and data acquisition card to collect target spectral signal and transmit it to the computer calculating the whole temperature profile.In order to meet the requirement of high accuracy of the temperature measurement, this paper focused on two works as follows:First, sphere was replaced by paraboloid as the collimation lens and focuing lens of the optical splitting system, as a result, the dispersion spot size of the characteristic spectrum was reduced, which eventrualy improved the extraction accuracy of the characteristic spectrum line.Second, standard radiation source was used to calibrate the transfer function of light intensity of the system, the system measurement error therefore was reduced.The wavelength calibration experiment proved that the central wavelength extraction accuracy of the characteristic spectral lines was better than that of 1nm. The experiment that measuring the temperature of the spectral radiant illuminance standard lamp showed that the relative measurement accuracy of the system was 2.21%.