Design And Study Of Parts Of The Key Circuits Of Portable Short-Range Laser Range Finder

With the development of laser technology from the 1960s, people pay more and more attention to the laser range-finding techniques, because only optical waves can be focused adequately, compared with radio and ultrasonic waves. In recent years, one of the development trends in laser range finder is to study how to improve the accuracy and resolution and realize the downsizing of system. In this thesis, the research on short-range high accuracy range finding system, which is inexpensive and compact, is done. To design the laser transmitter and the timing circuit is the main task.Variety of timing methods are analyzed and compared, then the scheme of this thesis is made. By combining the traditional counting method with time stretching method, the accuracy and resolution of timing circuit can be greatly improved. So the range finding system can maintain a high resolution at low frequency. Therefore it can decrease the difficulty of design and the cost. The time division circuit and latch counter are integrated in one chip of programmable logic device, which makes the size greatly decreased. The laser transmitter consisted of laser diode can decrease the scale and the weight of the range finding system and can achieve the requirement for short-range finding system.The design concepts of these two key circuits are presented and the simulation and experiments with these circuits are accomplished. The results prove that the scheme is feasible. Some of the weekness are derived, during simulating or debugging, from the techniques mastered nowadays. And methods of modification are proposed, which are mainly presented on clamping circuit and method of compensating for the errors of count results. Thus the performance of system can get further improvement.