简介:经济技术的发展,使得国际交往日益频繁、方便.为了提高出入境通关速度,满足人们越来越多的商务及旅游活动的要求,国际民航组织(ICAO)1980年向各国政府推荐了机读旅行证件的国际标准(ICAODoc9303-1980),并很快得到了众多国家响应.1989、1992年ICAO又两次对上述国际标准进行了修订.至今,国际旅行人数比较多的国家基本上都已经采用了ICAO推荐的机读旅行证件.1989年底起我们开始研制我国第一代机读旅行证件设备.由于ICAO推荐的机读旅行证件采用的是OCR技术,研制OCR扫描器就成了必要一环.
简介:WorkhasbeendonewithextendingtheusefulimaginganddetectionrageofCCD.ThiswasaccomplishedthroughdirectopticalcouplingandbondingofimageintensifierstotheCCD.IthasbeenshownthattheusefulrangeofaCCDmaybeextendedtwoordersofmagnitudeusingthesetechniquesincouplingamicrochannelplateimageintensifiertotheCCDarray.AlloftheseworksweredonewithpresentlyavailableCCDmadebyChina
简介:WiththehelpofCCDimages,therealizationofhighprecisionpo-sitioningandmeasurementhasbecomethebasicstandardformachinevisionandrealtimephotogrammetrysystems.However,deformationandothersortsofdegradationoccurringduringtransmissionaremajorlimitingfactorsofthepreci-sionattainablewithmostcurrentCCDcamerasandframegrabbers.SoapreciseradiometricandgeometrictransmissionofimagesfromCCDsensortomemoryisafundamentalaspectofCCDcameracalibration.Thegeometriccalibrationsystem,whichusessomeimageprocessingalgorithmsoftheCCDcamerabasedonthere-searchedanddevelopedsystemisdiscussed.Thereliabilityandvalidityarealsodiscussed.TheexperimentalresultsforthecalibrationoftheCCDarraywillbetakenasanimportantqualityindexforCCDevaluation.
简介:TN2532003021143光纤电压传感器最新进展=Recentadvancesinfiber-opticvoltagesensors[刊,中]/唐丽杰(北方交通大学光波技术研究所.北京(100044)),吴重庆…//半导体光电.—2002,23(4).—228-232综述了光纤电压传感器近年来国内外的最新研究进展,包括可用于SF6绝缘高压开关的光纤电压传感器、频率调制型的光纤电压传感器以及光控灵敏度的光纤电压传感器。介绍了国内在光纤电压传感器方面的研究进展,包括以DSP为信号处理芯片的BGO晶体的光纤电压传感器,以及应用光纤传感器机理来测试脉冲电压和电场的方法,并对光纤电压互感器暂态信号处理的原理进行了研究,试验证明可以满足继电保护的要求。图10参
简介:InordertoevaluatetheimagingqualityofCCDcamerasfullyandrapidly,theminimumresolvablecontrast(MRC)ispresentedinthispaperandthesystemofmeasuringMRCisconstructedaswell,inwhichtwointegratingspheresareproposedtoilluminatetwosidesofthetargetrespectively.Thevariablecontrastcanbeobtainedbyregulatingtheluminanceofintegratingspheres.Experimentalresultsindicatethattheerrorofmeasuringluminanceiswithin±0.3cd/m2,MRCriseswiththeincreaseofthespatialfrequency.TheexperimentalresultsshowthatthemethodproposedisaneffectiveapproachtoevaluatetheimagingqualityofCCDcameras.