Design Of A Pulse Collimated High Power Led Light Source For LED Light Radar

Lidar which based on laser is a kind of active modern optical remote sensing equipment.It is widely used in the fields of atmospheric environmental monitoring with high spatial and temporal resolution and continuous detection capacity.But subject to the limitations of the laser wavelength,its application in the field of aerosol detection is affected.LED light source has many advantages,which is better than laser as the source of atmospheric lidar.With the characteristics of rich in wavelength of LED,it's easy to detect optical properties of aerosols in the specific wavelength and gain its particle size distribution.In addition,using LED as emission signal of lidar will allow the equipment miniaturization and low-cost becoming possible.A pulse collimated high power LED light source for LED light radar is designed in this thesis.From the beginning of the detection mechanism of optical lidar and the main features of LED,the thesis mainly solves three problems,including the energy gathering of the LED light source,the beam quality and the light pulse modulation.Firstly,a nanosecond pulse circuit is designed to generate high voltage and narrow pulse signal using the avalanche effect of the avalanche transistor and capacitor discharge based on technology of energy compression.And according to the analysis of volt-ampere characteristics and thermal properties of LED,a driving circuit with constant current is designed to guarantee stable luminescence of high power LED.Secondly,the LED source model is analyzed in this thesis.A LED array composed of 7 single high power LED is designed to solve the problem of energy shortage of single LED.At the same time,Zemax optical software is used to design an optical device for LED —TIR collimator in order to improve the energy utilization of LED chip and to simplify the design of the later light path.Thirdly,for the larger area of LED array,a combination method of lens and light guide rods is used to collimate light with Zemax optical software.the collimation system is simulated and optimized.The result shows that the system meets the requirements of lidar and prove the rationality of the system design.Finally,according to the optimization results,the light source system experiment is carried out with pulse driving.The divergence angle of system is measured to be 20.75 mrad.