A Preliminary Study On Non-contact And High Resolution Laser Speckle Method For Temperature Detecting

Temperature measurement is an archaic topic in research, but it is still difficult to measure temperature in many fields because of the form of heat transmit, the complexity and variety of object. In this thesis, a new measurement of temperature distribution using laser speckle imaging is put forward, which can monitor the dynamic temperature movement of the object's surface without scan and contact. This measurement would have beautiful application foreground in the area of bio-medical for its preferable time and space resolution.Small particles suspended in liquid can undergo Brownian motion, which on average leads to no net displacement of the particle. Since higher temperature can lead to more rapid Brownian motion, we study the quantitative relationship between the twain by laser speckle imaging. And the velocity of Brownian motion would be used to calculate the information of temperature distribution. How to calculate the Brownian motion velocity of suspended particles using laser speckle imaging is the key of this method.Dynamic light scattering (DLS) experiment is designed to confirm the auto- correlation function of liquor model. Then the equation between the speckle contrast and the relative velocity of Brownian particles is developed.In order to validate the relationship between the velocity of Brownian motion and the absolute temperature, another experiment is carried out, and the result indicates that the square of the velocity of Brownian motion and the absolute temperature are linear in specific range.Then the laser speckle method is used to measure the dynamic movement of temperature distribution of liquor model's surface, and the planar temperature movement is reconstructed in time scale. The thermocouple is taken as a comparison with the laser speckle method. And the result of this comparison reveals that the laser speckle method has better time and space resolution.As a new principle and method for temperature measuring, it is still insufficient in practical use. At the end of this thesis we proposed some efficient advice to improve this method.