Papers by Keyword: Speckle Pattern Interferometry

Abstract: To improve the accuracy of the transient temperature detection system, Transient temperature inversion processing algorithms is proposed based on spectrum analysis of speckle pattern interferometry. The interference fringes is formed by speckle interferometry in the system, and due to transient temperature changes cause the material strain, so that the speckle interference pattern changes. the interference fringes on the measured surface is obtained by the area array CCD collection before and after deformation. The corresponding spectrum density function will changes by the changes of transient temperature, and the amplitude changes of center wavelength is 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, derived the amplitude and phase function of the transient temperature change and interference fringes, so as to provide the necessary conditions for detecting the use of spectral density function temperature. Experiment using 660nm laser diode, SI6600 type area CCD detector to obtain the speckle pattern interference fringes, system extracts the amplitude ratio of the central wavelength from spectral distribution function, and by calculation and calibration the detection accuracy of temperature can be achieved of 2°C. Compared to traditional methods that is direct detection for interference fringes changes, the new methods improve the accuracy by nearly an order of magnitude. It is more accurate detection and better uniformity, better stability.

Abstract: The two-dimensional deformation of wood with different grains under shearing loads was measured using an electronic speckle pattern interferometry (ESPI) technique. The radical, tangential and end sections of Douglas firs (Pseudotsuga menziesii) were used as specimens. Results revealed that the deformation values significantly vary for every part of the specimens, and the ring directions of earlywood and latewood, which compose the annual rings, have an effect on the two-dimensional deformation of wood.

Abstract: The two-dimensional deformation of wood under shearing loads is measured using an electronic speckle pattern interferometry (ESPI) technique. The radical and tangential sections of Douglas firs are used as specimens in the longitudinal direction. Results reveal that large two-dimensional deformation of the wood can be measured using the ESPI technique, the deformation values significantly vary for every part of the specimens, and the ring directions of earlywood and latewood, which compose the annual rings, have an effect on the two-dimensional deformation of wood.