脉冲激光测速系统发射与接收模块的设计

摘  要
激光测速是从六十年代中期发展起来的，利用激光的单色性和能量聚集的特点用测频的方法直接测物体的速度。比起老式的雷达测速仪，激光测速仪不仅具有更大的有效工作范围，而且它利用点射技术，能够在拥挤的车流之中固定跟踪某一个目标，准确率更高。
文中对激光测速系统硬件电路中各部分功能进行了详细的叙述，并说明了它们在该硬件电路中的工作原理和性能参数。在激光发射方面，使用半导体激光二极管和高性能驱动芯片产生高质量的光脉冲作为测速信号；在光信号接收方面，使用对特殊波长响应度极高的低噪声的雪崩二极管作为接收器件，利用高带宽放大芯片结合高速比较器提取有用信号。
 
关键词：脉冲激光测速,半导体激光器,驱动电路,雪崩光电二极管, pulsed laser velocimeter, semiconductor laser,driver circuit,APD

ABSTRACT

Laser velocimeter technology is developed from the mid-1960s. It takes the advantage of lasert's characteristics of monochromaticity and concentrating of energy, by measuring the frequency to directly measure the speed of the object.Compared with tranditional radar velocimeter, the latest laser velocimeter has great improvement in performance. Moreover, laser velocimeter not only has the advantage of larger effective working area, but also has the capability to use the technology of pointing emission to keep tracking of a certain object in corwded heavy traffic with higher precision. Thus, the main goal of laser velocimeter is to enforce the scrutiny of overspeed vehicle,and to correct and deal with overspeed driving in time, so as to prevent and reduce the incidence of taffic accident.
This article is detailedly introduced the function, the operational principle as well as the performance parameters of each portion of the circuit.In the transmitting modules,we generate good light pulse.This light pulse have steep and steady rising edge and narrow width.The single pulse must have adequate power,or we cannot receive the echo signal,beeause it has been submerged by noise. Then we design the receiving mode using APD and amplifier and comparer obtaining the useful signal.

Key words：pulsed laser velocimeter; semiconductor laser;driver circuit;APD

脉冲激光的发射部分采用555多谐振荡器产生一定频率的时钟信号利用计数系统的CPLD产生频率为10KHz、占空比为0.025%脉冲信号，以此信号输入能够产生15A的瞬时脉冲电流，匹配的上升和下降时间(25ns)的驱动芯片MIC4452，然后去驱动高性能的半导体激光二极管SPLLL85，输出上升时间为15ns，单次发射能量为10W的脉冲光信号作为测速的探测信号。
光信号的接收模块：利用对850ns波长响应度极高、灵敏度为65A/W、反向工作电压为250V、相应时间为0.5ns的雪崩二极管Si-APD，SPD-052转换接收到的光信号，输入高带宽，增益可调(10-400)的放大芯片UA733。根据特定测距范围的回波信号的能量大小设定增益值，最后利用高速(10ns)比较器件MAX9l3对信号进行滤波，滤除噪声信号。高速比较器的比较电平更具实验测得的一般噪声信号电平的大小来确定。最后得出的脉冲信号输入高精度计数模块作为触发信号。
 








目  录 21000字
摘  要 I
ABSTRACT I
1 绪论 1
1.1 引言 1
1.2 国内外研究历史、现状和发展趋势 1
2 激光测速系统 2
2.1 几种测速方式原理及性能比较 2
2.2 激光测速原理以及特点 3
2.3 激光测速系统工作过程 3
2.4 激光测速方法设计 4
2.4.1 脉冲法测速 4
2.4.2 相位法测速 6
2.4.3 脉冲法和相位法比较 8
2.5 可行性论证与误差分析 9
3 脉冲激光发射电路设计 10
3.1 设计思路 10
3.2 器件的选型 11
3.2.1 半导体激光器 11
3.2.2 驱动芯片 12
3.3 驱动电路的设计 13
3.3.1 555定时器 13
3.3.2 MAXPLUSII简介 14
3.3.3 MAXPLUSII仿真 15
4 反射脉冲激光接收电路设计 16
4.1 设计思路 16
(毕业设计:www.2bysj.cn)
4.2 器件的选型 16
4.2.1 光电探测器件 16
4.2.2 前置放大器 20
4.2.3 前置放大器的选择 21
4.2.4 高速比较器 24
4.3 总体电路设计 25
5 结论 26
致  谢 28
参考文献 29