| The laser active imaging technology uses a laser as the auxiliary light source to illuminate the target to enhance the target's reflected signal.Compared with passive imaging,it can get images all-weather,acquire more abundant information and have a longer range of performance.At present,many of the world's military powers regard this technology as an important research project and have also developed many related products.Range gating technique is an effective method for suppressing laser backscattering,which can improve the active imaging system's working distance and imaging quality,and widely be used in border defense surveillance and active detection.Firstly,this paper studies the principle of distance gated laser imaging and the attenuation and dispersion characteristics of the laser during atmospheric transmission.The imaging SNR model of the system is simulated using Matlab,and the laser wavelength,single pulse energy,and divergence angle are analyzed.The influence of the gate width on the imaging and the experimentally determined exposure pulse parameters of the detector were combined.The synchronous control technology was analyzed and the requirements for synchronous control were determined.Secondly,a synchronous control system with Cyclone 4 series FPGA as the core is designed.The control circuit receives control parameters from the host computer,and generates a pulse width,delay,and frequency adjustable control signal to trigger the laser and gated camera to achieve distance gating.Imaging.The use of Verilog HDL language modular programming control circuit software code,to achieve the PLL multiplier,control parameter reception,synchronization work signal generation and other functions.Finally,the hardware is debugged and the synchronous control is completed within the range gate.The test results show that the pulse width,delay,and frequency of the control signal are adjustable.The delay and pulse width step resolution is 5ns,and the delay range is 0-300?s. |
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