The Research And Design Of Laser Ranging System

The electro-optical range finder is an early physical range finder method which is studied..The emergence of laser promotes the development of electronic distance measuring. Laser has a strong directional, high brightness, good monochromaticity, suitable as a light source of photoelectric distance measurement. Pulse laser range finder is the first applications of laser. And the Phase Laser Ranging has the advantages of its small size, light weight, measuring accuracy that has nothing to do with the distance, so it is extensively applied to various project fields.Fist of all, the two methods of the laser ranging are described based on pulse method and based on the phase method, respectively. Then the principle of phase laser range finder is introduced in details. Through studying the theory of the phase laser range finder, phase Laser Ranging System based on CPLD is designed. The diagram of the system is given, as well as hardware circuit diagram of transmit and receiving block diagram of the each module. The system mainly includes:frequency source generating circuit, laser diode driver, optoelectronic receiving circuit,mixer circuit, band-pass filter circuit, voltage comparing circuit.The system uses differential frequency of phase measuring techniques. This can reduce the measurement frequency, extend the measurement period, reduce the measured phase error, so the measurement accuracy is increased.Frequency synthesis using PLL technology is used to produce laser modulation signal and local oscillator signals. It ensures the frequency stability. It adopts PIN photodiode to receive optical signals of reflecting back,to the mixer and mix with local oscillator signal to get differential frequency signal, after filtering and the voltage comparing processing,to phase detecting,counting, calculation and so on in CPLD.Finally, the system errors generated is theoretically analyzed, and specific solutions are introduced. The deficiencies of the system are analyzed and the work to be carried out after that is given.