光子数分辨探测激光测距研究

发布时间：2018-10-24 11:27

【摘要】：单光子探测技术结合时间相关单光子计数方法(TCSPC)将探测灵敏度提升至量子极限,在远距离或弱光眼安全激光测距和三维成像中有重要应用价值。然而在强背景光环境中,单光子探测器动态范围有限且容易饱和。而在无法长时间累计测量的情况下,由于没有足够的累积计数,TCSPC无法抑制背景噪声。本文提出将光子数分辨探测方法应用于激光测距,提高了光子探测器动态范围和测量速率,解决了实际应用中远距离、强背景、和高速移动目标的测量难题。我们发展了基于多像素光子计数器(MPPC)的光子数分辨探测器,最大可分辨光子数超过10个。基于光子数分辨探测器,不仅使激光测距系统的探测灵敏度达到了单光子水平,并且获得了回波脉冲的光子数信息,通过提高光子数阈值,有效地抑制了背景干扰。实验中,当光子数阈值为5光子／脉冲时,噪声计数降低了1个数量级。但是,由于MPPC光子数分辨探测器的暗计数大,尤其是像素点之间的串扰严重,使得多光子计数概率远超过实际背景光的多光子分布,消弱了光子数分辨探测方法消除背景的能力。针对MPPC光子数分辨探测器的以上不足,我们提出了多通道单光子探测器符合计数激光测距方法,降低探测器噪声,消除了多像素探测器之间的串扰,提高了抑制背景噪声的能力。通过双通道单光子探测器符合计数方法,信噪比提高到了8.54dB。在强背景光的环境下,单通道单光子探测器的背景计数高达5M/秒,在少光子数水平下,只探测单个激光脉冲即可实现快速移动目标的距离测量。
[Abstract]:The single-photon detection technique combined with the time-dependent single-photon counting method (TCSPC) increases the detection sensitivity to the quantum limit and has important application value in the remote or weak optical eye safe laser ranging and 3D imaging. However, in strong background light environment, the dynamic range of single photon detector is limited and easy to saturation. However, TCSPC can not suppress background noise because there is not enough cumulative count for long time accumulative measurement. In this paper, the application of photon digital resolution detection method to laser ranging is proposed, which improves the dynamic range and the measuring rate of the photon detector, and solves the problems of measuring long distance, strong background and high speed moving target in practical application. We have developed a photon number resolution detector based on the multipixel photon counter (MPPC). The maximum resolvable photon number is more than 10. Based on the photon digital resolution detector, the detection sensitivity of the laser ranging system is not only up to the single photon level, but also the photon number information of the echo pulse is obtained. By raising the threshold of the photon number, the background interference is effectively suppressed. In the experiment, when the threshold of photon number is 5 photon / pulse, the noise count is reduced by one order of magnitude. However, due to the large dark count of the MPPC photon number resolution detector, especially the serious crosstalk between pixels, the multiphoton counting probability is far greater than the multi-photon distribution of the actual background light. It weakens the ability of photon number resolution detection method to eliminate background. In view of the above shortcomings of the MPPC photon digital resolution detector, we propose a multi-channel single-photon detector coincidence counting laser ranging method, which reduces the detector noise and eliminates the crosstalk between the multi-pixel detectors. The ability of suppressing background noise is improved. The signal-to-noise ratio (SNR) is increased to 8.54 dB by the coincidence counting method of two-channel single-photon detector. In the environment of strong background light, the background count of single-channel single-photon detector is as high as 5M/ second. At the level of small photon number, the distance measurement of fast moving target can be realized by only detecting a single laser pulse.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN249

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