The Hardware Design About Pulsed Laser Range Finder

The Laser Range Finder is the application that combined laser technology,electronic technology, single chip microcomputer control technology, the technology of signal controlling and processing, precision mechanical technology and other technology together. Laser Range Finder is an instrument that used for measuring distance, which is based on the time-domain reflection principle. It is widely used in the fields of aerospace, automatic control, industrial, military, geodetic survey and building surveying. And the good accuracy is more and more needed in these days. Therefore, it is necessary for us to study and design a low-cost and high-precision Laser Range Finder. This essay introduces a Laser Range Finder that based on the principle of equivalent sampling, which could reach the purpose that said before.After studying various schemes, this essay finally used the principle of equivalent sampling to measure the time interval. At the premise of receiving the periodic reflect-pulse signals, using the principle of equivalent sampling, which is also the method to obtain and reconstruct the signal waveform by multiple trigger and sampling, could proportionally broaden the signal in time domain. And this method could get the important information in time domain, which could be used by the MCU to get the value of distance. The hardware circuit of this scheme is finally realized by long term studying and practicing. The ns-level signal is extended to ms-level signal, which could improve the accuracy of the Laser Range Finder. And, at the same time, this scheme could reduce the cost and designing difficulty.This paper introduces the Pulsed Laser Range finder’s hardware design, including the laser emission circuit which is based on the laser diode of SPL LL90₃, the laser receiving circuit which is based on the laser diode of AD500₉, and the MCU circuit which is based on MSP430. In the section of laser emission, I introduce the reason why I use SPL LL90₃, the modulation circuit of emitting and sampling signal, and the generating and driving circuit of laser pulse. In the section of laser receiving, I introduce the reason why I choose AD500₉, the acquisition circuit of receiving pulse signal, and the modulation circuit if receiving signal. In the section of MCU, I simply describe the external circuit of MCU.In the end of this paper, I show the experimental waveform and analyze the final conclusion of this system about Laser Range Finder.