Detection and Signal Processing

Wilhelmus Jacobus Witteman

• 12 februari 2010
• 9783642067372

Samenvatting:

This comprehensive monograph deals with detectors, signal processors and related noise phenomena. Detailed quantitative analyses are developed in a consistent format for thermal detectors, vacuum detectors, semiconductor detectors and avalanche detectors, as well as their accompanying noise currents. For signal processing applocations, the monograph treats in detail the operational amplifier, signal averagers, waveform analyzers, correlation techniques and heterodyne detection. Several original extensions are reported, especially for correlation devices and heterodyne detection with noise rejection. In addition, results of analyses are illustrated with examples of operating systems and of applications in space communication and laser radar.

Thewritingofthisbookhasbeeninspiredbytheexperienceofteachinga courseonDetectionandSignalProcessingtograduatestudentsoveraperiod ofmanyyears. Itwasstrikingthatstudentswerenotonlyfascinatedbythe variousdetectionprinciplesandtechnicalperformancesofpracticalsystems, butalsobytheprofessionalismoftheinvolved typical physicalengine- ing. Usuallystudentsarethoroughlytaughtindi?erentcoursesofphysics, whicharemostlystudiedasisolated?elds. Thecourseondetectionands- nalprocessingisbasedontypicalresultsthatwereestablishedindi?erent disciplines like optics, solid state physics, thermodynamics, mathematical statistics,Fouriertransforms,andelectroniccircuitry. Theirsimultaneousand interdependentapplicationbroadenstheinsightofmutualrelationsinthev- ious?elds. Forinstancethe?uctuationsofthermalbackgroundradiationcan bederivedeitherwiththeblackbodytheoryorindependentlywithther- dynamicstoarriveatthesameresult. AlsotheappliedFourierrelationsin thefrequencyandtimedomainsarenolongerabstractmathematicalman- ulationsbutpracticaltoolsandprobablyeasiertounderstandintheapplied technique. Estimatesoftheorderofmagnitudeswithcomparisonofrelevant physicale?ectsnecessarybydesigningadeviceareveryinstructive. Ingeneral theachievementsofvariousdisciplinesarebroughttogethertodesignandto evaluatequantitativelythetechnicalperformancesofdetectiontechniques. Thustheinterestfordetectionandsignalprocessingisbothtolearnthe knowledgefordesigningpracticaldetectionsystemsandtogetacquainted withthethinkingofphysicalengineering. The?rstpartofthebookisdevotedtonoisephenomenaandradiation detectors. Fundamentaldescriptionswithquantitativeanalysesoftheund- lyingphysicalprocessesofbothdetectorsandaccompanyingnoiseleadto understandthepotentialswithrespecttosensitivityandoperatingfrequency domain. Thesecondpartdealswithampli?cationproblemsandtherecovery ofrepetitivesignalsburiedinnoise. Thelastpartisdevotedtosolvingthe problemsconnectedwithreachingtheultimatedetectionlimitorquantum limit. Thisisdoneforheterodynedetectionandphotoncounting. Although VIII Preface heterodynedetectionyieldstheultimatesensitivity,itsspatialmodesel- tivityand,ingeneral,thelowspectralpowerdensityofthesignalrequire sophisticatedprovisions. Thisisdiscussedindetail. Theinherentproblemsare analyzedandappropriatetechnicalsolutionsaredescribedtoreachtheul- matesensitivityfordetectingincoherentradiationandcommunicationsignals thatarerandomlyDopplershifted. Theresultsareillustratedwithexamples ofspacecommunication. Hengelo(O),January2006 W. J. Witteman Contents 1 RandomFluctuations...1 1. 1 Introduction...1 1. 2 ThermalNoiseofResistance...2 1. 3 ShotNoise...5 1. 3. 1 SpectralDistribution ...6 1. 3. 2 Photons...10 1. 4 FlickerNoise...10 1. 5 Generation-RecombinationNoise...10 1. 6 ThermalRadiationandItsFluctuations...13 1. 7 TemperatureFluctuationsofSmallBodies...18 1. 7. 1 AbsorptionandEmissionFluctuations...20 2 Signal-NoiseRelations...21 2. 1 SignalLimitation...22 2. 2 BackgroundLimitation...22 2. 2. 1 IdealDetection...24 2. 3 JohnsonNoise...27 2. 4 DarkCurrentNoise...27 2. 5 NoiseandSensitivity...28 2. 6 Ampli?erNoiseandMismatching...28 3 ThermalDetectors...31 3. 1 ThermocoupleandThermopile...31 3. 2 Bolometer...36 3. 2. 1 MetallicBolometer...39 3. 2. 2 Thermistor...40 3. 3 PyroelectricDetector...44 4 VacuumPhotodetectors...51 4. 1 VacuumPhotodiode...52 4. 2 Photomultiplier...56 X Contents 5 SemiconductorPhotodetectors...61 5. 1 Photoconductors...6 1 5. 1. 1 AnalysisoftheDetectionProcess...64 5. 1. 2 FrequencyResponse ...69 5. 2 Photodiodes...69 5. 2. 1 P-NJunction...70 5. 2. 2 Current-VoltageCharacteristic...72 5. 2. 3 PhotonExcitation...75 5. 2. 4 OperationalModes...79 5. 2. 5 OpenCircuit ...80 5. 2. 6 CurrentCircuit...82 5. 2. 7 Reverse-BiasedCircuit...83 5. 3 AvalanchePhotodiodes...