Study Of Laser Radar, High-frequency High-power Laser Diode Driver

With the increasing demands for ladar products, ladar is playing a more important role for its small element size,light, high resolution, anti-interference. The development of the scannerless. ranging ladar brings about new demand for the light source of the semiconductor laser. A high-frequency modulated high-power laser source is necessary for the accuracy measurement at long distance laser ranging.High-frequency continuous modulation on the high-power semiconductor laser is required in our ladar system. The theory and driving methods of the semiconductor laser is summarized in this article. Two kinds of driving circuit including linear power amplifier and resonance power amplifier are designed for continuous and quasi continuous modulated laser. The principle and scheme of the circuit is introduced, and the design and the function of the sub-module are expounded. For the sake of accurate measurement of electric performance, an APD testing circuit is designed. I can draw the conclusion after experiments and analysis: the linear power amplifier circuit could successfully drive a LOW LD with the continuously frequency tunable from 1MHz to 5MHz; the resonance power amplifier circuit has a tunable frequency from 1MHz to 20MHz with a peak current output up to 10A, succeeding in driving the laser diode array.A half-wave modulation scannerless ladar system based on phase laser ranging is demonstrated. Its laser source and photo-receiver is modulated by different waveform with the same frequency. Image intensifier is selected as the photo-receiver to amplify the reflected signal from the object which is exposed to laser of the high-power laser diode. Then, the received signal is captured by the CCD device and is transferred to the computer to get the distance information by some calculating. An experimental system based on the new scheme is established, after the experimental comparison of the two different means of modulation, the results are: the new solution could reduce power dissipation effectively, improve the contrast of the image and remain the same measuring precision. Then, some possible improvements are made to reduce the measuring deviation. At the last of the dissertation, I sum up my work and have an outlook for it.