[Research on transient temperature detection by spectrum function variation of speckle pattern interferometry].

To improve the accuracy of the transient temperature detection system, transient temperature inversion processing algorithms was proposed based on spectrum analysis of speckle pattern interferometry. The interference fringes were formed by speckle interferometry in the system, and due to transient temperature changes that cause the material strain, the speckle interference pattern changes. The interference fringes on the measured surface were obtained by the area array CCD collection before and after deformation. The corresponding spectrum density function will change with the changes in the transient temperature, and the amplitude changes of center wavelength were inverted by the speckle pattern interferometry. Through detecting and calculating the ratio of the amplitude of the center wavelength, the transient temperature can be obtained by spectrum analysis. In the analysis and calculation for the function of transient temperature and material strain, material strain and interference fringes, the amplitude and phase function of the transient temperature change and interference fringes were derived, providing the necessary conditions for detecting spectral density function temperature. The experiment used 660 nm laser diode and SI6600 type area CCD detector. By extracting the offset of the center wavelength from the spectrum distribution function, the calculation and calibration data were compared to the data obtained with the traditional method of interference temperature detection, and the result showed that the detection accuracy can achieve 0.3%. Compared to traditional direct detection of interference fringes changes, the accuracy improved nearly three times by the method.