用于轻气炮弹速测量的新型高信噪比激光测速系统

New laser projectile velocity-measuring system with high SNR for light-gas gun

传统激光测速系统易受高温弹前激波发光和空间电磁场的影响,从而导致系统信噪比下降。为获取高质量信号波形,设计了一种可用于轻气炮弹速测量的新型激光测速系统,并提出了激光光路和光电转换电路的改进方法。采用光纤对激光进行引导,避免长引线的使用,增强了系统抗干扰能力。选择输出功率40mW的固体激光器作为系统光源,设计了具有滤光、聚光功能的复合式激光接收探头,提高了信号光强度。详细分析了测量电路的噪声与带宽,改进和优化了光电转换电路,测量电路的信噪比提升为98dB。轻气炮弹速实际测试结果表明,使用该测速系统获得的信号波形质量良好,测速结果相对扩展不确定度为0.73%,满足轻气炮弹速测量系统需求。

The traditional laser projectile velocity system is susceptible to the impact of high-temperature frontal shock luminescence and space electromagnetic field, resulting in a decrease in the system’s signal-to-noise ratio. In order to obtain high-quality signal waveforms, a new type of laser projectile velocity measurement system that can be used for light-gas gun is designed, and improved methods of laser light path and photoelectric conversion circuits are proposed in this paper. The use of optical fiber to guide the laser avoids the use of long leads and enhances the system’s anti-interference ability. A solid-state laser with an output power of 40 mW was selected as the system light source, and a composite laser receiving probe with filtering and focusing functions was designed to increase the signal light intensity. The noise and bandwidth of the measurement circuit are analyzed in detail, and the photoelectric conversion circuit is improved and optimized. The signal-to-noise ratio of the measurement circuit is increased to 98 dB. The actual test results show that the signal waveform quality obtained by the laser projectile velocity measurement system is good, and the relative expanded uncertainty of the velocity measurement result is 0.73%, which meets the requirements of the light-gas gun projectile velocity measurement system.