High Speed Velocity Measurements. Laser Interferometer System Architecture And Algorithm Research

One of the most important parameters can be got from the instantaneous velocity measure in the detonation and shock wave experiments. For its advantages of non-contact measure and high precision, the technology of speed measurement by the way of laser interference is used more and more widely. Further more, the laser interference velocity measurement system with the all-fiber architecture is leading an important trend in the shock wave and detonation experiments because it has such advantages as compact structure, high precision, a big velocity measurement upper limit.In the dissertation, the basic theory will be disscused, the structure and the performance of the system will be described, and the arithmetic for the data processing will be introduced.Firstly, in the dissertation, the development of some major velocity measurement technologies and systems in the history of laser interference speed measurement is reviewed firstly. And then an analysis of their system characteristics and data processing methods is presented. Finally, the all-fiber speed measure system with displacement interference technology comes up.The theory of this system is based on the optic Doppler principle and the optic frequency mixing principle. On this basis and in accordance with the system requirement, the characteristics of both the system's signal collection and its major devices are described, and an analysis of the relationship between the instantaneous frequency and the velocity is also made.Secondly, according to the device type and its structure, the performance of the system and the main factors of the error of the system are analyzed. And then, the solution of decreasing the error is given.Thirdly, this dissertation states that the signal collected by the system can be understood to be nonlinearity and non-stationary according to its character and that the speed of the object can be got by way of measuring the instantaneous frequency of the signal. The arithmetic for the non-stationary signal is also showed, which can be divided into the linearity distribution and the quadratic distribution. Furthermore, the wavelet transformation with the improvement for our system is employed for the data processing. The main improvement is the optimization of the ridge.Finally, the simulation curve is generated according to the equation of the flying plate and the result from the detonation and shock wave experiments in reference books. A very good result is achieved by using the arithmetic in the dissertation to process the simulation curve.The system introduced in the dissertation must be promising and valuable in practice owing to its compact structure, high precision, easy adjustment and wide speed range. In the dissertation, both the structure and the index of the main device of velocity measurement system which velocity measurement upper limit is high to 7000 m/s is presented, and the signal processing method based on the improved continous wavelet transform to get the instantaneous frequency is used which will get the velocity history of the object accurately. The related report of the high speed measurement system and the improved signal processing method for the system has not been seen in home and abord.