单光子激光雷达具有探测灵敏度高、响应速度快、测量精度高等优势,但在实际工作中易受到背景噪声等问题干扰.针对海面远距离平程目标测量,提出基于高速数字信号全通道实时处理(digital signal process,DSP)研究,通过分析海面上空大气溶胶对激光测量的影响,分析不同的海面能见度对测量系统造成影响的差别,对比相同海域条件下常规测距与单光子测距威力的差别,同时开展适应海面环境的单光子回波通道的数字处理算法研究.在良好天气条件下,对海岸线静止目标53 km大山(发射光学衰减10 dB)探测概率高于95％,对海上38 km运动渔船等小目标进行实时跟踪测量,获得到目标距离信息,且该系统工作稳定可靠.

最大测程是脉冲激光雷达的重要指标,也是其测距性能的综合体现.本文从脉冲激光雷达测距方程入手,对影响最大测程的因素进行了分析,简要地给出了最大测程设计中的考虑要素.文章从工程实践的角度,对当前脉冲激光雷达的检测方法进行了优、缺点分析,并针对不同条件给出了最大测程的快速估算方法.这些估算方法立足于工程实践,具有计算量少、成本低、结果直观、应用方便灵活等优点,能够更好地指导用户开展性能检测、维修评估等工作,具有较高的推广应用价值.

The monitor of sea fogs become more important with the rapid development of marine activities. Remote sensing through laser is an effective tool for monitoring sea fogs, but still challengeable for large distance. We demonstrated a Long-distance Lidar for sea fog with superconducting nanowire single-photon detector (SNSPD), which extended the ranging area to a 180-km diameter area. The system, which was verified by using a benchmark distance measurement of a known island, is applied to the Mie scattering weather prediction Lidar system. The fog echo signal distribution in the range of 42.3∼63.5 km and 53.2∼74.2 km was obtained by the Lidar system. Then the fog concentration and the velocity of the fog were deduced from the distribution, which is consistent with the weather prediction. The height of the sea fog is about two hundred meter while the visibility at this height is about 90 km due to the Earth’s radius of curvature. Therefore, the capability of this SNSPD-based Lidar was close to the theoretical limit for sea fog measurements for extremely high signal-to-noise ratio of SNSPD.

Superconducting nanowire single photon detector (SNSPD) is a competitive candidate in laser ranging at 1064 nm wavelength compared with other single photon detectors such as InGaAs/InP APD for its high sensitivity, high time precision and low dark counts. In this paper, we apply our SNSPD to a laser ranging system measuring target in Qinghai lake area with atmospheric scatter. The echo photons are received by telescope, and transport through the multimode fiber to the SNSPD photon-sensitive area. The SNSPD, integrated in an optical cavity with a resonant wavelength of 1064 nm, is fabricated on a MgF2 substrate. The optical absorption of NbN film goes up to 98% according to FDTD simulation, and the system efficiency is measured to be about 40%. A pulsed laser at 1064 nm, featuring a peak power of 12 MW and a pulse width of 10 ns, is adopted in the laser ranging system. In this experiment, we first measure the system intrinsic noise and the environment noise introduced into the laser ranging system after turning off the laser. After that, we measure the echo rate for the target at 126 km, which increases up to 96% with an attenuator of 10 dB at the receiver side. The maximum distance of the laser ranging system is analyzed based on the experimental results of dark count and echo rate through a theoretical model of laser radar. The analysis indicates that signal-to-noise ratio (SNR) is increased smoothly with the accumulation of time. At the same time, we simulate how the dark counts influence the capability of laser ranging system based on SNSPD, the simulated SNR matches well with the experimental data of target at 126 km. Furthermore, the dark counts, accumulation of time and probability of echo photon affect the SNR according to the simulation results, showing that large dark counts would result in SNR fluctuation and signal annihilation when the probability of echo photon is low. Thus, the maximum distance of laser ranging under the assumption of integration time is estimated through the SNR simulated result, showing that a maximum distance is up to 280 km, 40 km far away from APD detector based system under the same conditions mainly due to the very low dark counts of SNSPD. It should be pointed out that the coupling efficiency between SNSPD and the receiving telescope is low for small view field limited by the 62.5 m fiber of SNSPD. Thus, further work is to fabricate SNSPD with a larger coupling area which is possible to increase the maximum distance with improved coupling settings.

为了提高激光雷达的测距威力,文章提出了一种脉冲激光回波信号的数字化检测方法,采用高速AD器件将回波通道进行数字化转换,利用超低阈值对回波数据进行一次固定阈值检测,然后对回波脉冲数据进行二次动态阈值检测,并对二次检测结果采用先跟踪再检测技术,降低虚警率,提高弱小目标检测正确性及检测概率。

临床资料 患儿,男,出生3天,足月顺产,体重2.8 kg.出生后发现掌跖、肛周部弥漫性红斑及皱缩干性脓疱,拟诊为"大疱性表皮松解症"于2009年6月17日收入儿科住院.经抗感染、支持及局部常规清洁换药无好转且渐加重,请皮肤科会诊.

目的 探讨肺炎支原体肺炎患儿外周血IgE、IL-13与IL-18的水平及其临床意义.方法 118例病例均选自2003年1月至2004年1月间住院的患儿,符合支原体肺炎的诊断标准.入院患儿检测IgE、IL-13与IL-18及病原学检查.同时选择80例健康体检的婴幼儿作为正常对照组.结果 肺炎支原体感染患儿血中IgE、IL-13与IL-18明显高于对照组.结论 肺炎支原体感染可刺激机体产生特异性IgE,诱导Ⅰ型变态反应进而导致肺炎患儿出现晚期气道高反应.肺炎支原体感染发病机制与细胞免疫功能紊乱、外周血T淋巴细胞失衡有关。

目的:探讨肺炎支原体肺炎患儿外周血T淋巴细胞表达IL-13、IL-18的意义。方法:采用ELISA检测106例肺炎支原体肺炎患儿(肺炎组)血中IL-13、IL-18,同时采用人免疫球蛋白E酶联免疫定量测定试剂盒检测IgE含量,并与80例健康小儿(对照组)对照比较。结果:肺炎组患儿血中IgE、IL-13、IL-18明显高于对照组(P<0.005或P<0.001)。结论:肺炎支原体感染发病机制与细胞免疫功能紊乱、外周血T淋巴细胞存在失衡有关。

目的研究8-异前列腺素F2α(8-Ⅰ-PGF2α)在早产儿脑白质损伤及神经行为评价中的临床意义.方法 2002年12月-2005年3月在新生儿ICU住院的46例早产儿,纠正胎龄为40周行NBNA评分;于生后48 h使用头颅B超对早产儿颅内监测,根据脑室内出血程度分为正常组、轻度损伤组(Ⅰ级、Ⅱ级脑室内出血)及重度损伤组(Ⅲ级、Ⅳ级颅内出血).ELISA法分别检测3组间脑脊液中8-I-PGF2α.结果正常组31例,NBNA评分为(39.1±0.2)分;轻度损伤组9例,NBNA评分为(37.4±1.5)分;重度损伤组6例,NBNA评分为(31.3±3.4)分(不包括放弃治疗的2例病人).轻、重度损伤组早产儿共5例(轻度损伤组2例,重度损伤组3例),其中并伴有4例脑室周围白质软化,此5例患儿脑脊液中8-Ⅰ-PGF2α均在300 pg/mL以上.通过把8-Ⅰ-PGF2α分成<150 pg/mL、(150～250) pg/mL及>250 pg/mL三个区间,发现<150 pg/mL患儿 NBNA为(38.3±1.5)分;(150～250) pg/mL患儿NBNA为(34.9±2.4)分,>250 pg/mL患儿NBNA为(30.2±3.1)分.三区间NBNA评分比较有统计学意义(F=6.598,P<0.001).结论早产儿严重的颅内出血患儿早期有脑脊液8-I-PGF2α升高,早期监测8-I-PGF2α及脑室内出血程度可能对其神经行为预后有一定的判断作用.

目的:观察胰岛素样生长因子-1(IGF-1)、表皮生长因子(EGF)在窒息后新生儿血中的变化,探讨出生窒息对新生儿胃肠激素的影响.方法:用放射免疫分析法(RIA),测定40例窒息新生儿和30例正常足月新生儿出生后1 d、3d、7 d血中IGF-1、EGF的水平变化.结果:窒息新生儿血中IGF-1、EGF均比正常对照组显著下降(P＜0.01);窒息后新生儿恢复期IGF-1、EGF升高.结论:窒息后新生儿血中IGF-1、EGF的水平下降,表明窒息新生儿胃肠激素水平异常,可能是造成患儿消化功能紊乱的因素之一.