外文翻译CCD图像.docx
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外文翻译CCD图像.docx
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外文翻译CCD图像
附录
附录1
翻译部分
RawCCDimagesareexceptionalbutnotperfect.Duetothedigitalnatureofthedatamanyoftheimperfectionscanbecompensatedfororcalibratedoutofthefinalimagethroughdigitalimageprocessing.
CompositionofaRawCCDImage.
ArawCCDimageconsistsofthefollowingsignalcomponents:
IMAGESIGNAL-Thesignalfromthesource.Electronsaregeneratedfromtheactualsourcephotons.
BIASSIGNAL-InitialsignalalreadyontheCCDbeforetheexposureistaken.ThissignalisduetobiasingtheCCDoffsetslightlyabovezeroA/Dcounts(ADU).
THERMALSIGNAL-Signal(DarkCurrentthermalelectrons)duetothethermalactivityofthesemiconductor.ThermalsignalisreducedbycoolingoftheCCDtolowtemperature.
SourcesofNoise
CCDimagesaresusceptibletothefollowingsourcesofnoise:
PHOTONNOISE-Randomfluctuationsinthephotonsignalofthesource.Therateatwhichphotonsarereceivedisnotconstant.
THERMALNOISE-StatisticalfluctuationsinthegenerationofThermalsignal.Therateatwhichelectronsareproducedinthesemiconductorsubstrateduetothermaleffectsisnotconstant.
READOUTNOISE-Errorsinreadingthesignal;generallydominatedbytheon-chipamplifier.
QUANTIZATIONNOISE-ErrorsintroducedintheA/Dconversionprocess.
SENSITIVITYVARIATION-SensitivityvariationsfromphotositetophotositeontheCCDdetectororacrossthedetector.ModernCCD'sareuniformtobetterthan1%betweenneighboringphotositesanduniformtobetterthan10%acrosstheentiresurface.
NoiseCorrections
REDUCINGNOISE-ReadoutNoiseandQuantizationNoisearelimitedbytheconstructionoftheCCDcameraandcannotbeimproveduponbytheuser.ThermalNoise,however,canbereducedbycoolingoftheCCD(temperatureregulation).TheSensitivityVariationscanberemovedbyproperflatfielding.
CORRECTINGFORTHEBIASANDTHERMALSIGNALS-TheBiasandThermalsignalscanbesubtractedoutfromtheRawImagebytakingwhatiscalledaDarkExposure.ThedarkexposureisameasureoftheBiasSignalandThermalSignalandmaysimplybesubtractedfromtheRawImage.
FLATFIELDING-Arecordofthephotositetophotositesensitivityvariationscanbeobtainedbytakinganexposureofauniformlylit'flatfield".ThesevariationscanthenbedividedoutoftheRawImagetoproduceanimageessentiallyfreefromthissourceoferror.Anylengthexposurewilldo,butideallyonewhichsaturatesthepixelstothe50%or75%levelisbest.
TheFinalProcessedImage
ThefinalProcessedImagewhichremovesunwantedsignalsandreducesnoiseasbestwecaniscomputedasfollows:
FinalProcessedImage=(Raw-Dark)/Flat
AllofthedigitalimageprocessingfunctionsdescribedabovecanbeaccomplishedbyusingCCDOPSsoftwarefurnishedwitheachSBIGimagingcamera.ThestepstoaccomplishthemaredescribedintheOperatingManualfurnishedwitheachSBIGimagingcamera.AtSBIGweofferourtechnicalsupporttohelpyouwithquestionsonhowtoimproveyourimages.
HOWTOSELECTTHECORRECTCCDIMAGINGCAMERAFORYOURTELESCOPE
WhennewcustomerscontactSBIGwediscusstheirimagingcameraapplication.Wetrytogetanideaoftheirinterests.Wehavefoundthismethodisaneffectivewayofinsuringthatourcustomersgettherightimagingcamerafortheirpurposes.Someofthequestionsweaskareasfollows:
Whattypeoftelescopedoyoupresentlyown?
HavingthisinformationallowsustomatchtheCCDimagingCamera'sparameters,pixelsizeandfieldofviewtoyourtelescope.WecanalsohelpyouinterfacetheCCDimagingcamera'sautomaticguidingfunctionstoyourtelescope.
AreyouaMACorPCuser?
Sinceoursoftwaresupportsbothoftheseplatformswecaninsurethatyoureceivethecorrectsoftware.Wecanalsoanswerquestionsaboutanyuniquefunctionsinoneortheother.Wecansendyouademonstrationcopyoftheappropriatesoftwareforyourreview.
Doyouhaveatelescopedrivebasewithanautoguiderport?
Doyouwanttooperatefromaremotecomputer?
CompanieslikeSoftwareBisquefullysupportourproductswithtelescopecontrolandimagingcamerasoftware.
Doyouwanttotakephotographicqualityimagesofdeepspaceobjects,imageplanets,orperformwidefieldsearchesfornearearthasteroidsorsupernovas?
InlearningaboutyourinterestswecanbetterguideyoutotheoptimumCCDpixelsizeandimagingareafortheapplication.
Doyouwanttomakephotometricmeasurementsofvariablestarsordeterminepreciseasteroidpositions?
FromthisinformationwecanrecommendaCCDimagingcameramodelandexplainhowtousethespecificanalysisfunctionstoperformthesetasks.Wecanhelpyoucharacterizeyourimagingcamerabyfurnishingadditionaltechnicaldata.
Doyouwanttoautomaticallyguidelonguninterruptedastrophotographs?
AsthecompanywiththemostexperienceinCCDautoguidingwecanhelpyouinstallandoperateaCCDautoguideronyourtelescope.TheModelSTVhasaworldwidereputationforaccurateguidingondimguidestars.Nomatterwhattypeoftelescopeyouownwecanhelpyoucorrectlyinterfaceitandgetitworkingproperly.
SBIGCCDIMAGINGCAMERAS
TheSBIGproductlineconsistsofaseriesofthermoelectricallycooledCCDimagingcamerasdesignedforawiderangeofapplicationsrangingfromastronomy,tricolorimaging,colorphotometry,spectroscopy,medicalimaging,densitometry,tochemiluminescenceandepifluorescenceimaging,etc.Thiscatalogincludesinformationonastronomicalimagingcameras,scientificimagingcameras,autoguiding,andaccessories.Wehavetriedtoarrangethecatalogsothatitiseasytocompareproductsbyspecificationsandperformance. ThetablesintheproductsectioncomparesomeofthebasiccharacteristicsoneachCCDimagingcamerainourproductline.Youwillfindamoredetailedsetofspecificationswitheachindividualimagingcameradescription.
HOWTOGETSTARTEDUSINGYOURCCDIMAGINGCAMERA
Itallstartswiththesoftware. Ifthere'sanycompanywellknownforitsoutstandingimagingcamerasoftwareit'sSBIG. OurCCDOPSOperatingSoftwareiswellknownforitsuserorientedcameracontrolfeaturesandstability. CCDOPSisavailableforfreedownloadfromourwebsitealongwithsampleimagesthatyoucandisplayandanalyzeusingtheimageprocessingandanalysisfunctionsoftheCCDOPSsoftware.Youcanbecomethoroughlyfamiliarwithhowourimagingcamerasworkandthecapabilitiesofthesoftwarebeforeyoupurchaseanimagingcamera. WealsoincludeCCDSoftV5andTheSkyfromSoftwareBisquewithmostofourcamerasatnoadditionalcharge. MacintoshusersreceiveafreecopyofEquinoXplanetariumandcameracontrolsoftwarefortheMacOS-Xoperatingsystem. NoothermanufactureroffersbettersoftwarethanyougetwithSBIGcameras. NewcustomersreceivingtheirCCDimagingcamerashouldfirstreadtheinstallationsectionintheirCCDOPSOperatingManual.OnceyouhavereadthatsectionyoushouldhavenodifficultyinstallingCCDOPSsoftwareonyourharddrive,connectingtheUSBcablefromtheimagingcameratoyourcomputer,initiatingtheimagingcameraandwithinminutesstarttakingyourfirstCCDimages. Manyofourcustomersareamazedathoweasyitistostarttakingimages. AdditionalinformationcanbefoundbyreadingtheimageprocessingsectionsoftheCCDOPSandCCDSoftV5Manuals.Thisinformationallowsyoutoprogresstomoreadvancedfeaturessuchasautomaticdarkframesubtractionofimages,focusingtheimagingcamera,viewing,analyzingandprocessingtheimagesonthemonitor,co-addingimages,takingautomaticsequencesofimages,photometricandastrometricmeasurements,etc.
APERSONALTOUCHFROMSBIG
AtSBIGwehavehadmuchsuccesswithaprograminwhichwecontinuallyreviewcustomer'simagessenttousondiskorviae-mail. Wecanoftendeterminethecauseofaproblemfromactualimagessentinbyauser.Wereviewtheimagesandcontacteachcustomerpersonally. Imagesdisplayingpoortelescopetracking,improperimagingcamerafocus,oversaturatedimages,etc.,aretypicalinitialproblems. Wewillhelpyouquicklylearnhowtoimproveyourimages. Youcanbeassuredofpersonaltechnicalsupportwhenyouneedit. ThecustomersupportprogramhasfurnishedSBIGwithalargecollectionofremarkableimages. ManycustomershavehadtheirimagespublishedinSBIGcatalogs,ads,andvariousastronomymagazines. Wewelcomethechancetoreviewyourimagesandhopeyouwilltakeadvantageofourtrainedstafftohelpyouimproveyourimages.
TRACKANDACCUMULATE (U.S.Patent#5,365,269)
UsinganinnovativeengineeringapproachSBIGdevelopedanimagingcamerafunctioncalledTrack&Accumulate(TRACCUM)inwhichmultipleimagesareautomaticallyregisteredtocreateasinglelongexposure. Sincethelongexposureconsistsofshortimagesthetotalcombinedexposuresignificantlyimprovesresolutionbyreducingthecumulativetelescopeperiodicerror. IntheTRACCUMmodeeachimageisshiftedtocorrectguidingerrorsandaddedtotheimagebuffer.Inthismodethetelescopedoesnotneedtobeadjusted. ThegreatsensitivityoftheCCDvirtuallyguaranteesthattherewillbeausableguidestarwithinthefieldofview.Thisfeatureprovidesdramaticimprovementinresolutionbyreducingtheeffectofperiodicerrorandallowingunattendedhourlongexposures. SBIGhasbeengrantedU.S.Patent#5,365,269forTrack&Accumulate.
DUALCCDSELF-GUIDING (U.S.Patent#5,525,793)
In1994withtheintroductionofModelsST-7andST-8CCDImagingCameraswhichincorporatetwoseparateCCDdetectors,SBIGwasabletoaccomplishthegoalofintroducingatrulyself-guidedCCDimagingcamera. TheabilitytoselectguidestarswithaseparateCCDthroughthefull
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