The Application Of Speckle Measurement In Engineering Nondestructive Testing

In recent years, the accuracy requirements for the detection and measurement on physical quantities such as vibration, distance, velocity, flow rate, displacement, etc, have been increased significantly. The speckle measurement technology has become the focus of research beacause of its high measurement precision, the overall testing, the fast measuring speed and the low requirements for measuring devices.The main work of this thesis is as follows:first, through reading relevant books, to know the development and present situation of speckle technology, and researche the formation, type and optical properties of speckles. Second, through theoretical analysis, three methods are compared and the eleetronic speekle pattern interferometry is selected. Third, several methods of image processing are found by the experiments. In the end, a new measurement system is designed. A semiconductor laser is used as the source in this system. Then through a beam splitter, the incident light irradiant the objects to be measured. The last, CCD camera is used to record the interference image of the reflected light and the reference light. When the object is heated, the reflected light have small changes, and these changes will reflect in the speckle pattern. Through the speckle pattern to determine whether the object is qualified.Compared to ultrasonic testing, radiographic testing, magnetic particle testing and other traditional nondestructive detection method, this method is a new measurement method. First, this measurement technique is a kind of optical measurement technique, which has the characteristics of non pollution. Secondly, this technique has so many advantages such as short detection time, high performance-price ratio, and simple operation. So it is very suitable for application in engineering. In the end, this thesis concludes that the system can integrate the theoretical knowledge with the characteristics of practical application, by taking the actual test environment. Also the system is easy to set up with, considerable capability of anti-interference, and can obtain relatively accurate test results which make this system have potential practical value.