Sensors, Signals and Noise

Size: px

Start display at page:

Download "Sensors, Signals and Noise"

Trevor Boyd
5 years ago
Views:

1 Sensors, Signls nd Noise COURSE OUTLINE Introduction Signls nd Noise Filtering Sensors: PD1 PhotoDetector Fundmentls Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 1

2 Photons nd photodetector principles Photons nd Spectrl rnges Reflection nd Absorption of Photons in mterils Therml Photodetector Principles Quntum Photodetector Principles Photon Sttistics nd Noise Current Signls of Quntum Photodetectors Appendix: S-R theorem Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 2

3 Photons nd Spectrl rnges Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 3

4 Photons Light = electromgnetic wves with frequency ν nd wvelength λ propgtion speed (in vcuum) c = 2, m/s Spectrl rnges: c= λν λ< 400nm Ultrviolet (UV) 400nm < λ < 750nm Visible (VIS) 750nm < λ < 3 μm Ner-infrred (NIR) 3 μm < λ < 30 μm Mid-infrred (MIR) 30 μm < λ Fr-infrred (FIR) Photon: quntum of electromgnetic energy E p = hν quntum energy ( Plnck s constnt h = 7, J s) Rther thn E p in Joules, the electron-voltge V p is employed: E p = qv p (electron chrge q = 1, C ) V p in Volts (or electron-volts ev) Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 4

5 Photon Energy nd Momentum Photon Energy E p inversely proportionl to the wvelength = = from = we get universl constnt hc/q= 1, m V 1,24 μm V V p V p hc1 = q λ 1,24 = λ 400nm < λ < 750nm VIS rnge 3,10 ev > V p > 1,65 ev 750nm < λ < 3μm NIR rnge 1,65eV > V p > 0,41 ev with V p in Volts nd λin μm Photon Momentum p p Ep h pp = = c λ The photon momentum is much smller thn the momentum of electrons. In the electron trnsitions in solids due to photon bsorption the electron momentum is lmost constnt while the electron energy is remrkbly incresed, so tht the trnsition is lmost verticl in the energy-momentum digrm Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 5

6 Reflection nd Absorption of Photons Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 6

7 Reflection of Photons on the surfce Incident P P I Reflected Air P R Incoming power in the mteril P T0 = P I -P R P T0 Semiconductor (or other mteril) x At the surfce strong discontinuity of the refrction index n, from n = 1 for ir to n >1 for semiconductor: e.g. for silicon it is bout n 3,4 nd depends on the wvelength. This discontinuity gives high reflection coefficient R PR R= (e.g. for silicon R > 0,4 wvelength dependent) P I Anti-reflection coting: deposition on the reflecting surfce of sequence of thin dielectric mteril lyers with progressively decresing n vlue. It provides grdul decreseof the n vlue from semiconductor to ir nd such smoother trnsition reduces the reflection Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 7

8 Absorption of Photons in mterils Incident P I P T0 1 ( ) = R P I Reflected P R P T trnsmitted P bsorbed P R= P R I Air L Semiconductor x For moderte or low P T the bsorption in dxis proportionl to P T (liner optic effect) = α = dx dpt Pdx T PT L The opticl power trnsmitted to position xis ( α ) exp( ) P = P exp x = P x L T T0 T0 The opticl power bsorbed from 0 to xis x αx L P = PT 0 PT = PT 0( 1 e ) = PT 0 1 e α = opticl bsorption coefficient L = 1/α= opticl bsorption depth which for x<<l leds to P PT0 L Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 8 x

9 Absorption of Photons For given mteril the opticl bsorption STRONGLY depends on the WAVELENGTH. Typicl exmple: Silicon bsorption coefficient 1,E+07 α Absorption Coefficient of Silicon, undoped crystl α [cm -1 ] log 10 scle 1,E+06 1,E+05 1,E+04 1,E+03 1,E+02 1,E+01 1,E+00 1,E-01 1,E-02 1,E-03 1,E-04 1,E-05 1,E-06 1,E-07 Visible rnge 1,E λ[nm] liner scle Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 9

10 Absorption of Photons For given mteril the opticl bsorption STRONGLY depends on the WAVELENGTH. Typicl exmple: Silicon bsorption depth 1,E+08 L = 1/α Absorption depth in Silicon, undopedcrystl 1,E+07 L [cm] log 10 scle 1,E+06 1,E+05 1,E+04 1,E+03 1,E+02 1,E+01 1,E+00 1,E-01 1,E-02 1,E-03 1,E-04 1,E-05 Visible rnge 10 9 μm = 1km 10 6 μm = 1m 10 3 μm = 1mm 1 μm 1,E-06 1,E λ[nm] liner scle 10 3 = 1nm NB: over the visible rnge L vries with λby two orders of mgnitude!! Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 10

11 Therml Photodetector Principles Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 11

12 Principle of Therml Photodetectors A principle for detection of light signls is to employ their energy simply for heting trget nd mesure its temperture rise ΔT. Detectors relying on this principle re clled «Therml Photodetectors» or «Power Detectors» Min dvntge: very wide spectrl rnge. Since photons just hve to be bsorbed for contributing to the detection, the rnge cn be extended fr into the infrred. Min drwbck: sensitivity is inherently poor, becuse high number of bsorbed photons is required for producing even smll vritions of temperture ΔT in tiny trget. For instnce: blue photons re required for heting by ΔT=0,1 K wter droplet of 1mmdimeter (blue photons t λ=475nm hve V p = 2,6 ev; wter hs specific het cpcity c T = 4186 [J/Kg K]= 2, [ev/kg K] nd the mss is 1mg) The dynmic response is inherently slow, becuse therml trnsients re slow. Therml detectors re minly suitble for mesurement of stedy rdition. Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 12

13 Principle of Therml Photo-Detectors P p = opticl power; n p = photon rte Pp = np Ep = np qvp Electricl Signl V D Absorber vrible temp. T Temperture sensor Absorber: T = temperture, C = het cpcitnce C = c m (m = mss; c = specific het cpcitnce) R T Therml resistnce (Kelvin deg/wtt ) P d = therml power flow T To = RT Pd nlog to Ohm lw V = R I Denoting for simplicity T = T -T o the detector energy blnce is Het sink or therml mss with constnt temp. T o Pdt= CdT+ p T R T dt Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 13

14 Principle of Therml Photo-Detectors From the energy blnce T Pdt p = CdT + dt RT dt Pp T we get = nd in Lplce trnsform dt C RC T p = The detector trnsfer function from opticl power to mesured temperture thus is T = PR p T 1 1+ src P T C RC The stedy stte response (the stedy T = P p R T obtined with stedy P p ) increses s the therml resistnce R T is incresed The dynmic response is single-pole low-pss filter with chrcteristic time constnt τ = R T C : s R T is incresed, the bndlimit f T =1/2πR T C is decresed For improving the high-frequency response without reducing the stedy response it is necessry to reduce the het cpcitnce C = c m. This implies tht ) bsorber mterils with smll specific het cpcitnce c re required b) the bsorber mss m should be minimized. Remrkble progress hs been indeed chieved in therml detectors with modern technologies of minituriztion nd integrtion (of bsorber, temperture sensor, etc.) tht mke possible to fbricte lso multipixel rrys of therml detectors T st T Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 14

15 Rdint Sensitivity or Spectrl Responsivity Therml detectors trnsduce the opticl power P P in n electricl output signl V D of the temperture sensor (voltge signl of thermoresistnces in Bolometers nd of thermocouples in Thermopiles). The bsic quntittive chrcteriztion of the performnce of the detector is given by the Rdint Sensitivity (lso clled Spectrl Responsivity) S D, defined s electricl output voltge [in V] S D = opticl power on the detector sensitive re [in W] For given bsorbed power the detector is heted t given level, independent of the rdition wvelength λ. Therefore, uniform S D would be obtined t ll λif the reflection nd bsorption were constnt, independent of λ. Vritions of reflection nd bsorptionvs λre kept t moderte level with modern bsorber technologies. Firly uniform S D is chieved over firly wide wvelength rnges, extended well into the infrred spectrl region. Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 15

16 Quntum Photodetector Principles Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 16

17 Principles of Quntum Photodetectors A different principle for the detection of light signls is to exploit photo-electric effects for producing directly n electricl currentin the detector. The energy of the bsorbed photons is used for generting free chrge crriers, which constitute the elements of the detector current. Detectors relying on this principle re clled «Quntum Photodetectors» or «Photon Detectors» Photon Detectors cn be vcuum-tube or semiconductor devices Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 17

18 Principles of Quntum Photodetectors -q R L A K -q + - V A Outline of Vcuum-Tube detector devices: Photo-Tubes or Photo-Diodes An electrode (cthode K) in vcuum enclosure receives the photons By photo-electric effect the cthode emits electrons in vcuum. The electrons re drwn by the electric field to nother electrode bised t higher potentil (node A) Current flows through the terminls (photocthode nd node). Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 18

19 Depletion lyer Principles of Quntum Photodetectors n + p -- p + R L A -q -q +q + +q V A - K Outline of Semiconductor detector devices: Photo-Diodes Photons impct on reverse-bised p-n junction diode The bsorbed photons rise electrons from vlence bnd to conduction bnd of the semiconductor, thereby generting free electron-hole pirs. The free crriers generted in the zone of high electric field (the depletion lyer)re drwn by the junction electric field (the electrons to the n-terminl nd the holes to the p-terminl) Current flows through the terminls. Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 19

20 Quntum Detection Efficiency Quntum photodetectors trnsduce opticl signls in electricl current signls by collecting the free electrons generted by the photons of the opticl rdition. The bsic quntittive chrcteriztion of the performnce of the detector is given by the Quntum Detection Efficiency (or Photon Detection Efficiency) η D defined s number of photogenerted electrons (or electron-hole pirs) η D = number of photons reching the detector = N N e p However, since in mny engineering tsks the focus is on the trnsduction from opticl power to electricl current, the Rdint Sensitivity S D is often employed lso for quntum photodetectors, defined s electricl output current [in A] S D = opticl power on the detector sensitive re [in W] = I P D L [ AW] Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 20

21 Quntum Efficiency nd Rdint Sensitivity Photons of wvelength λrriving with stedy rte n p on quntum detector convey n opticl power P L P = n hν L p the electrons (or e-h pirs) photogenerted in the detector with stedy rte n e produce current I = n q The Rdint Sensitivity is S D D e I n q n λ P n hν n hc q D e e = = = L p p nd since = S D D D [ m] λ λ µ = η = η hc q 1,24 We see tht the Rdint Sensitivity of the quntum detectors intrinsiclly depends on the wvelength λ,tht is, even with constnt quntum efficiency η D. This occurs becuse given opticl power P L corresponds to different photon rtes n p t different wvelengths λ Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 21

22 Quntum Efficiency nd Rdint Sensitivity The dt sheets of the detector mnufcturers usully report plots of the Rdint Sensitivity versus wvelength for quntum detectors. However, the dt of quntum detection efficiency cn be esily red in such plots: the eqution S D [ m] λ µ = ηd 1,24 shows how lines corresponding to given vlues of quntum efficiency cn be esily drwn in the plot. In plot with liner scles for both S D nd λthey re stright lines S D S D (λ) η D = 0,4 η D = 0,3 η D = 0,2 η D = 0,1 Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 22 λ

23 Photon Sttistics nd Noise Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 23

24 Photon Noise The opticl rdition is composed of photons rriving rndomly in time; the photon number in given time intervl Tis sttisticl vrible with men nd vrince = The rndom fluctutions of the photons re the noise lredy present t opticl level. This opticl noise cn be due to bckground photon flux nd to the ctul desired opticl signl. In most cses the photon sttistics is well pproximted (see lter) by the Poisson sttistics, so tht it is σ = 2 p Np The opticl power rriving to the detector is composed of qunt with energy hν rriving rndomly t rte n p. It is the nlog t opticl level of shot electricl current: the men opticl power is P p = n p hν (nlog to I e = n e q ); the shot opticl noise hs unilterl spectrl density S p (nlog to =2 ) hc S = 2hνP = 2 P λ p p p Note tht for given opticl power P p the shot noise density decreses s the wvelength λ is incresed Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 24

25 Photon Noise The photon shot noise is consistent with the Poisson sttistics of photons. This cn be directly verified by considering for given opticl power P p = n p hν to filter the opticl signl nd noise with gted integrtion GI weighting function T 1 Noise bndpss = DC gin = T t GI output signl E = PT = hν n T = hνn p p p p GI output noise It is thus confirmed tht ( ) 2 σ = S T f = 2hνP T f = hνpt = hνe = hν N E p p p p p σ 2 p σ = = 2 E 2 ( hν ) In fct, photons obey the Bose-Einstein sttistics. However, in most cses of interest for us the Poisson sttistics is stisfctory pproximtion of the B-E sttistics. For instnce, this is vlid for lsers operting bove threshold nd for light emitted from hot mtter in therml equilibrium (blck body rdition). Np Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 25

26 Photon Noise nd B-E sttistics For the therml rdition (blck body rdition), the tretment bsed on the B-E sttistics leds to correct the equtions obtined with the Poisson sttistics s follows 2 σ = N ( 1+ n ) Sp = 2hνPp ( 1+ nm) p p m The correcting term n m is the men number of photons t the energy level considered, computed with the B-E sttistics s The quntittive evlution of this correction shows tht devitions from the Poisson pproximtion re pprecible only t long λin the IR spectrl rnge, beyond limit tht depends on the temperture. For instnce, the correction is > 1% with n m > 0,01, tht is for hν< 4,6 kt, which corresponds t T= 300K to hν< 0,115 ev, i.e. to λ> 11μm t T= 1300K to hν< 0,498 ev, i.e. to λ> 2,5μm n m 1 = hν exp 1 kt Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 26

27 Current Signls of Quntum Photodetectors Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 27

28 Detector Current Pulse Signl In the trnsduction of opticl signls to current signls by Quntum Photodetectors the dynmic response hs cut-off t high frequency. Ultrfst opticl pulses re trnsduced to current pulses tht re still fst, but hve longer durtion. The response to multi-photon opticl signl is the liner superposition of the elementry responses to individul photons. The response to single photon is lso clled Single-Electron-Response SERbecuse photon genertes just one free electron (or one electron-hole pir). It is simply wrong to consider the SER δ-like current pulseoccurring t the time where the photogenerted chrge crrier impcts on the collector electrode. The crrier induces chrge in the collector electrode beforereching it; the induced chrge vries with the crrier position, so tht current flows during ll the crrier trvel in the electric field. The wveform of the current signl is obtined by tking the derivtive of the chrge induced on the collector electrode s function of time. To compute this chrge is n electrosttic problem not esy to solve in generl. However, the mthemticl tretment cn be remrkbly simplified by preliminrly computing the motion of the chrge crriers nd exploiting then the Shockley-Rmo theorem. Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 28

29 Shockley-Rmo theorem The output current due to n electron trveling towrds the collector electrode cn be obtined by pplying the Shockley-Rmo theorem in three steps 1. The motion of the electron must be computed; i.e. the trjectory nd the velocity t every point of it must be known 2. A reference electric field E v must be computed, which is the field tht would exist in the device (in prticulr long the electron trjectory) under the following circumstnces: electron removed output electrode rised t unit potentil ll other conductors t ground potentil 3. The Shockley-Rmo theoremsttes tht the current i c tht flows t the output electrode due to the electron motion cn be simply computed s i = qeiv = qe v c v c vc c where denotes sclr product nd is the component of the field in the direction of the velocity Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 29

30 Crrier motion in phototube (PT) K w -q A VACUUM PHOTOTUBE WITH PLANAR GEOMETRY w = cthode to node distnce V A = bis voltge = true electric field (in the -x direction) = potentil distribution Electric Field Potentil E D V D 0 I D - V A + w x V w A V A R L x x ELECTRON MOTION IN VACUUM (-q chrge; m mss) qed qva ccelertion c = = m mw qva Velocity vc = t c = t mw 0 v c Trnsit time t 2qVA m t 2m t = w qv A Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 30

31 K E v SER current in phototube (PT) 0 - A w 1 V A = 1 + w x 1 w x Referenceelectric E v field computed with electron removed; V A = 1 ; V K = 0 E True electron velocity v c v = = 0 v c w qv mw SR theorem: the output current due to single electron is A t t prllel to the x-xis prllel to the x-xis 2qVA m t i = qev = c v c 2 qva 2 mw t i c q w m 2qVA 0 t t Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 31

32 SER current in phototube (PT) In phototube with plnr geometry the single electron response (SER) is pulse with tringulr wveform i = qev = c v c 2 qva 2 mw t ( t t ) 0 i c q w m 2qVA 0 t t The frequency response is the Fourier trnsform of the SER pulse, which hs high frequency cutoff inversely proportionl to the pulse width. The pulse width is set by the trnsit time t of the electronfromcthode to node t m w = 2 = 3,37 10 q V A 6 w V A Typicl vlues for phototubes re round w = 1cm = 0,01m nd V A = 100V, which correspond to trnsit time round t 3,3 ns Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 32

33 Screened-Anode PT: crrier motion K V D E D w w g V G + V A + G w g w A x V A V w V A x G x w = w g V A A shorter SER pulse cn be obtined by inserting metl wire grid in front of the node The bsic ide is tht the grid cts s electrosttic screen tht does not llow n electron trveling from x=0(cthode) to x=w g (grid) to induce chrge on the node. The grid bis voltge is selected to minimize the perturbtion to the electron motion; i.e. it is set to the potentil V G corresponding to x=w g in bsence of the grid (or slightly below it). In these conditions, the electric field is prcticlly the sme s in the phototube structure without grid nd the motion of n electron in vcuum is lso the sme. Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 33

34 Screened-Anode PT: SR theorem K w w g G A Sme electron motion s in the phototube without grid Different evolution in time of the induced chrge on the node. V G = 0 V A = 1 x In fct, the reference field E v is now very different nd netly shows tht chrge is induced on the node only during the lst prt of the electron trjectory, i.e. from x=w g (grid) to x=w (node) E v w g w 1 w w x g Ev = 0 for 0< x< wg 1 E = for w < x< w w wg v g The SR theorem sttes tht the SER current is i = qev c v c Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 34

35 Screened-Anode PT for fster response K E v 0 w w g V G = 0 - G V A = 1 + w g w t t = t g A x 1 w w x g w w w v c True electron velocity qva = mw t Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/ i c 0 v c c t t Reference field of SR theorem SR theorem i c without grid g i = qev v c 2qVA m Ev = 0 for 0< x< wg 1 E = for w < x< w w wg v g t g i c with grid t t t g t t

36 Appendix: S-R theorem demonstrtion The theorem ws independently demonstrted for the motion of crriers in vcuumin 1938 by Willim Shockley 1 nd in 1939 by Simon Rmo 2 Extension to the motion of crriers in presence of spce chrge (s it is the cse in semiconductor devices) ws demonstrted in 1971 by Emilio Gtti et l 3 These demonstrtions were bsed on high-level concepts in electrosttic theory. Lter on, simple demonstrtion bsed on the "principle of virtul work (which exploits the energy conservtion) ws found. This demo is here summrized The S-R theorem considers situtions where liner superposition of effects is vlid (i.e. ll medi re liner). In such conditions: ) the totlchrge induced on given electrode is the liner superposition of the contributions induced by the other electrodes t different potentil nd by the point chrges present in the surrounding. b) the chrge induced specificlly by given crrier on given conductor depends only on the position nd chrge of tht crrier, it does not depend on the potentils of the electrodes nd on other point chrges present. 1. W. Shockley, J.Appl.Physics vol 9, (1938) 2. S. Rmo, Proc. IRE, (1939) 3. E. Gtti et l, Nucl.Instr.&Meth vol 92, (1971) Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 36

37 Appendix: S-R theorem demonstrtion Let us consider crrier of chrge qin given point of its trjectory (position vector ) nd ssume tht the collector electrode is kept t constnt voltge V=1 by bttery nd ll other electrodes re grounded. Note tht in these conditions the electric field is just the Reference Field E v of the S-R theorem. We do not intend to clculte the chrge tht the crrier in position induces on the collector electrode. We just wnt to clculte its vritioncused by the crrier motion. Let us suppose to displce by the crrier. Becuse of the displcement the crrier gins n energy dw = qeidx= qeivdt= qe vdt c v v c vc c The bttery keeps the potentil of the collector electrode constnt by bringing chrge dq from ground to the electrode nd therefore by supplying n energy dw = VdQ= 1 dq b There is no other energy exchnge, hence for energy conservtion dw = dw b c b nd therefore i c dq = = qe v dt vc c Sergio Cov SENSORS SIGNALS AND NOISE PhotoDetectors 1 -PD 1 rv 2013/12/20 37

COURSE OUTLINE. Introduction Signals and Noise Filtering Sensors: PD1 PhotoDetector Fundamentals. Sensors, Signals and Noise 1

COURSE OUTLINE. Introduction Signals and Noise Filtering Sensors: PD1 PhotoDetector Fundamentals. Sensors, Signals and Noise 1 Sensors, Signls nd Noise 1 COURSE OUTLINE Introduction Signls nd Noise Filtering Sensors: PD1 PhotoDetector Fundmentls Photons nd photodetector principles 2 Photons nd Spectrl rnges Reflection nd Absorption