The Research Of Laser Diode Ranging System Based On Phase

The laser ranging is a technology for precision measurement, it is developing along with the development of the laser technology, which is extensively used in the military field and the civil field because of its precise accuracy.A laser ranging system which is based on the principle of the phase difference measurement of sine wave is developed in this dissertation. Due to the excellent modulation characteristics of laser diode (LD), the infused current of the LD is modulated to make the intensity of the laser beam change with the modulation signal. The distance information can be got from the phase difference of the laser signal before the emission and the reflected laser signal which is detected. The key of this method is the accuracy of the phase difference detecting. A digital mixing and phase detecting method is discussed in the dissertation, the accuracy <1°. The specific work done in the dissertation is as following:At first, the theory of the laser ranging based on the principle of the phase difference measurement of sine wave is discussed and then the whole circuit system of the laser range finder is designed. The whole circuit system includes 5 parts as following: the LD modulation circuit, photoelectric detecting circuit, PLL frequency synthesize circuit, digital mixing and phase difference detecting circuit, and display circuit.Secondly, the photoelectric detecting circuit, digital mixing and phase difference detecting circuit are analyzed for emphasis and the circuit simulations are done. Then the tests are done.Thirdly, the soft ORCAD PSpice A/D is used for simulation. With the help of the simulation, the design was improved.At last, the research work is summarized and the discuss about the improvement for the system is brought forward in this dissertation.