Study Of Laser Ranging System Based On Nanosecond Pulse Driver Circuit

Laser pulse ranging system can provide a reliable solutions to the distance measurements with the advantage of low cost,small size and good stability.Hence,laser pulse ranging system is widely-applied to advanced technology research which includes laser communication,laser photography and etc.In this thesis,a high precision laser ranging system based on time of flight(TOF)method was made.The measurement accuracy is mainly limited by the pulse quality according to the principle of TOF.In this paper,we redesigned the pulse generator circuit and a optical pulse with nanosecond rising edge can be obtained which directly improve the measurement accuracy.Meanwhile,we also researched the error caused by echo signals' change and proposed the slope calibration algorithm.The experimental results show that the error generated by echo pulse degradation is suppressed significantly.The whole ranging system is based on embedded technology.The whole ranging system is based on embedded technology.The optical pulse generator photoelectric receiver,TDC timer and the slope calibration unit,were all highly integrated in one board,greatly reducing the size and cost.Finally,the system has been tested in mainly aspect of precision.Besides,variety of key parameters of this system have been presented according to the result of experiments.The following works of this thesis were completed by author independently.(1)A brief introduction of the development of laser radar in domestic and overseas is presented.Further more,plenty of laser radar schemes which are the typically application to daily life and industry field is discussed.(2)The principle of pulsed laser range finder which is used in this thesis has been introduced.Feasibility analysis,which is the foundation of system scheme,is investigated.Besides,the factors that will make an effect in measurement accuracy is analyzed.(3)The pulse quality is main characteristic limiting the measurement accuracy.Hence,the pulse generator circuit which uses a method combining the analog circuit and the digital circuit is redesigned and a optical pulse with nanosecond rising edge can be obtained.(4)Using the APD photo-detector,we proposed and demonstrated a simplified scheme that includes receive unit,amplifier,echo slope calibration and time digital conversion.Adopting a high precision difference measurement way.The hardware and software of TDC unit is designed,and the accuracy of time measure is about several ten ps quantity.(5)In order to improve the distance measurement accuracy from the echo signal,we proposed the slope calibration algorithm which can reduce the measurement error created by echo wave profile changes.The experimental results show that the measurement accuracy of the system is greatly improved.The experimental results show that,in the range of 0 to 30 m,the measurement error is1.1 cm.While in the range of 40 to 100 m,the error is about 7.5 cm.