简介:Photoconductivesemiconductorswitches(PCSSs)arewidelyusedinhighpowerultra-widebandsourceapplicationsandprecisesynchronizationcontrolduetotheirhighpowerlow-jitterhigh-repetition-frequency.Inthisletter,a14-mmgapsemi-insulatingGaAsPCSSbiasedunder20kVistriggeredbya1064-nmlaserwitharepetitionfrequencyof30Hz.Althoughthetriggerconditionisgreaterthanthethresholdofthelock-oneffect,thehighgainmodeisnotobserved.TheresultsindicatethatthehighgainmodeofthePCSSisquenchedbydecreasingtheremnantvoltageofpulsedenergystoragecapacitor.
简介:Acoupleofsimple-structurephasemodulatorswereusedinactivemode-lockedfiberlasertoimplementrepetitionratecontinuoustuning.Thelaserproducespulseasshortas5.7pswhoserepetitionratetuningcancoverthespacingoftheadjoiningordermode-lockingfrequencies.
简介:线阵CCD已广泛应用于在线检测、图像识别等系统,目前高帧率采集系统多在200~500Hz之间。高速线阵CCD采集系统,如1K甚至10KHz以上的采集要求,设计难度大,电路实现复杂,需要专用处理器,产品成本高,提出了一种采用并行高速FPGA驱动线阵CCD,通过常规分立元件完成模拟信号处理,实现数字信号实时传输的方案。该方案不仅简化了硬件设计上的难度,在同等性能情况下,可实现每秒万帧的高速采样,大幅度降低了成本。方案选用AlteraFPGA作为控制核心,实现高速信号采集的同时,在片上实现一定的图像算法,不仅加速了图像处理速度,同时降低了计算机的处理压力。最后,本电路通过USB2.0接口,完成数据的实时传输。设计具有高帧率、高灵敏度、性能稳定,便携使用等特点,同时还有一定的通用性,已应用于一些光学系统中。
简介:Alowcost8×10-Gb/stransmissionsystemover1500kmonconventionalfiberusingchirpedfiberBragggrating(CFBG)asdispersioncompensatorisdemonstrated.Thebiterrorrate(BER)below10-10at1500kmisobtained.Thechannelspacingis0.8nmandtheopticalamplifierspacingis100km.Only16erbium-dopedfiberamplifiers(EDFAs)areused.
简介:Real-timevideostreamingusingultra-wideband(UWB)technologyisexperimentallydemonstratedalonglong-reachpassiveopticalnetworks(LR-PONs)withdifferentwiredandwirelessreaches.ExperimentaltestsusingexternalanddirectmodulationwithUWBwirelessradiationinthe10-and60-GHzbandsareperformed.Anultra-bendablefiberisalsoconsideredforalast-miledistribution.ThevideoqualityattheoutputoftheopticalfiberinfrastructureoftheLR-PONisassessedusingtheerrorvectormagnitude(EVM),andthelinkqualityindicator(LQI)isusedasafigureofmeritafterwirelessradiation.AnEVMbelow–17dBisachievedforbothexternallyanddirectlymodulatedLR-PONscomprisingupto125kmofopticalfiber.EVMimprovementisobservedforlongerLR-PONswhendirectlymodulatedlasers(DMLs)areusedbecauseoftheamplitudegainprovidedbythecombinedeffectofdispersionandDML’schirp.Comparedwithopticalback-to-backoperation,theLQIleveldegradestothemaximumaround20%forLR-PONsrangingbetween75and125kmoffiberreachandwithawirelesscoverageof2minthe10-GHzUWBband.ThesamelevelofLQIdegradationisobservedusingthe60-GHzUWBbandwithaLR-PONintegrating101kmofaccessnetwork,alast-miledistributionusingultra-bendablefiber,anda5.2-mwirelesslink.
简介:介绍了车载红外告警系统中多目标的航迹建立及目标从图像坐标到载体坐标的转换方法。系统在方位360°视场内均匀布置了6个红外传感器,天顶方向布置1个红外传感器,形成360°全半球视场。每个传感器对应1个目标检测板,系统设计有1个系统控制板,用于对目标进行坐标转换、航迹管理以及向各个检测板发送控制命令。当目标检测板完成目标检测后,便向控制板发送7个传感器中的目标信息,控制板对目标进行坐标转换使之统一于载体坐标系,在载体坐标系建立目标航迹并对航迹进行预测管理,最后通过串口向上位机输出目标在载体坐标系的位置信息并报警。实验证明,转换后的目标位置完全正确,且误差小于1°,满足系统指标要求。