Study On The Measurement Of High-speed Deformation Displacement By Laser Doppler

Since the 20th century, with the development of modern industrial technology, the importance of measurement of vibration displacement in the industrial production and scientific research is broadly accepted by people, as it is an indispensable means which is used to research and solve practical industrial problem. There are a lot of methods for the measurement of vibration displacement. The method of vibration displacement measurement by Laser Doppler Effect has already became the important developmental direction of vibration displacement measurement (VBM), because there are many advantages such as high precision, fast dynamic response, wide measuring range, non-touchable measuring characteristics etc. From the point of view of practical application, this dissertation carries through the research of theory and experiment on the theory and signal detection, processing, and analysis of high speed Laser Doppler vibration displacement measurement (LPVDM), and it is utilized to measure the surface vibration displacement of the hermetical columniform pot while there is an explosion occurring inside.In chapter 1, several usually used methods of VBM are introduced, there advantages, disadvantages and applicable range are also introduced.The theory and basic light path are given in chapter2. And bases on the requirements of this item, a heterodyne LPDVM light path are designed, in order to realize the frequency shifting, an acoustooptic modulator is added in the reference light path, so the direction of the speed and be distinguish.As the signal is very weak, in chapter 3, a detection circuit for weak signal which involve the function of optoelectronic detection, signal filtering and amplification are designed, several methods are also introduced to decrease noise.The acquisition of signal and several processing methods for Laser Doppler signal are introduced in chapter 4, and the Short-time Fourier Transfer (SFT) method are tried to process the high frequency, wide bandwidth, wide dynamic range and nonstable signal of this system.In chapter 5, several kinds of experiments are conducted to validate the performance of this system, and the result shows that this system performs well.In the last part of this dissertation, deficiency of this system is described, and some amelioration advice is also given.