Design Of Constant Current And Temperature Driving Circuit For Laser Diode Laser

Lidar has been widely used in automatic driving,intelligent robot path planning and other fields because of its high resolution,strong antijamming ability and fast response.The output characteristic of laser light source is directly related to the measurement precision of laser radar,and the performance of laser driving circuit directly affects its output characteristic.Focusing on the application requirements of TOF and FMCW lidar,this paper focuses on the design and implementation of current drive control,temperature control and frequency modulation drive circuits.Firstly,the working principle and process of semiconductor laser are analyzed in detail,and two important factors affecting the output wavelength and power stability are pointed out: current and temperature.The basic driving principle of semiconductor laser is introduced.Two driving modes,constant current driving mode and pulse driving mode,are discussed and the driving scheme is determined.Secondly,according to the characteristics of the semiconductor laser,a set of current control and temperature control circuit is designed,which uses FPGA to control the temperature and current of the laser to control the output of constant power laser,CF laser and pulse laser.Thirdly,based on the selection of digital switch in FPGA control circuit,the laser temperature can be controlled quickly by changing the output voltage of balanced bridge of MAX1978 chip.Then the FPGA control program and DA circuit are used to control the switch of the digital chip in the driving circuit and output the pulse laser with adjustable pulse width and period.Finally,by establishing the actual circuit model,simulating the working state of pulse driving circuit and constant current driving circuit,using Multisim software,the circuit parameters are designed.Finally,the drive circuit board is tested.The test results show that the output current of the driving circuit is stable for a long time,the stability is0.01%.In the aspect of temperature control,the driving circuit can control the maximum temperature change within 0.01 ℃,and keep the long-term stability of 0.049%.The maximum fluctuation of laser output power is0.024 m W,and the long-term stability is 0.23%,which is about 40 times higher than that of non-driving current and temperature control system.By controlling the temperature of semiconductor laser,the operating temperature of laser can be adjusted from 23.91 ℃ to 26.16 ℃,the output wavelength can be controlled from 1550.095 ℃ to 1550.133 nm,and the tuning frequency can reach 2.5k Hz.The pulse width and period of pulsed laser with adjustable pulse width can reach 50 ns,which meets the requirements of time-of-flight laser radar.