Elektroniska sensorer Ljusregistrering

Transkript

1 Elektroniska sensorer Ljusregistrering

2 Fotoner Energikvantum E=hv Våg och partikel egenskaper

3 Fotoelektrisk effekt

4 Fotoelektrisk omvandling

5 Specifications: CCD type: Sony ICX249AK EXview CCD with ultra low dark current and vertical anti-blooming. CCD pixel data: Pixel size: 8.6 x 8.3uM with 64% fill factor, image format 752 x 580 pixels CCD size: Imaging area: 6.47mm (horizontal) x 4.83mm (vertical). Spectral response: Peak response at 590nM, 30% at 400nM (Violet) and 70% at 670nM (Near infra-red). Quantum efficiency: Approx. 65% peak at 590nM. Readout noise: Less than12 electrons RMS - Parallel Port, Less than 8 electrons RMS - USB Port Full-well capacity: Greater than 70,000 e- Anti-blooming: Overload margin greater than 800x Dark current: Dark frame saturation time greater than 100 hours. Less than 0.1 electrons/ second at +10C ambient. Data format: 16 bits interline imager. Computer interface: 8 bit unidirectional parallel port with bi-directional status lines (Standard Centronics interface). 25 pin 'D' style plug for LPT1, 2 or 3, via a 5 metre x 6mm diameter cable, OR USB port design Image download time: Typically 12 seconds with a 200MHz PC and 'Fast Interface' module. USB version approximately 3.5 seconds. Power requirements: 115VAC / 12VA, or 750 milliamps max. Cooling system: Regulated constant-current cooling supply built-in. Single-stage thermoelectric cooler to give a CCD temperature of approximately -30C below ambient. Size: 50 x 100mm black anodised aluminium barrel with M42 thread at CCD window end and 15 pin 'D' style input plug at rear. Weight: 200g.

6 CCD sensorn

7 Photogate

8 Blooming

9 Lateral Overflow Drain

10 Effekter av blooming (Smear) CMOS smear CCD smear

11 Transport av fotoelektroner

12

13 4 phase clocking

14 2 phase clocking

15 Full frame transfer

16 Frame transfer

17 Interline transfer

18 Mikrolinser

19 CCD / CMOS

20

21 Färgregistrering

22 Mosaik mönster

23 3 pass exponering

24 3 chip CCD

25 Jämförelse

26 Absorption

27 3 Lagerteknik

28 Jämförelse

29 CCD scanning format

30 Framerate Approximate Frame Rate (fps) = 1 / [(Npixel / tread) + Texp] Npixel är antalet pixlar som läses ur sensorn Tread är tiden det tar att läsa av en pixel Texp är exponeringstiden

31 True framerate Frame Rate (fps) = 1 / (Frame Acquisition Time + Frame Read Time) Frame acquisition time components: * Time required to clear charge from the parallel register prior to beginning integration. * Shutter opening delay in CCDs employing mechanical shutters. *Exposure time. *Shutter closing delay, if any. Frame read time components: *Time required to clear charge from the serial register prior to beginning readout. *Time required for a parallel row shift times the number of rows in the array. *Serial discard time multiplied by the number of pixels not intended to be read. *Serial conversion (digitization) time per pixel times the number of pixels to be read.

32 Clear time Parallell clear time Seriell clear time

33 Utläsning och shifttime

34 Discard times Parallell discard time Seriell discard time

35 Pixel binning

36 Sammanfattning Frame Acquisition Time = (TPR Nclear) + Topen + Texp + Tclose T(PR) =Parallell clear time Nclear = antalet clear cykler Topen = slutarens fördröjning vid öppning Texp = exponeringstiden Tclose = slutarens fördröjning vid stängning Frame Read Time = TSR + (Trow Nrow) + (TSD Ndiscard) + (tread Nread) TSR = Serial clear time Trow = parallell row shift time Nrow = antalet rader TSD = Serial discard time Ndiscard = Antalet ej lästa pixlar Tread = den seriella omvandlingstiden per pixel Nread = antalet pixlar som ska läsas ut

37 Sekventiell utläsning

38 Simultan utläsning

39 Dubbla seriella register

40 Frågeställningar Vilka parametrar styr bildhastigheten? Vilka möjligheter finns att öka bildhastigheten

41 Brus Read noise (elektroniska komponenter) Dark noise (termiskt) Photon noise (fluktuationer)

42 Dynamic range Dynamic Range = 20 x Log(Nsat/Nnoise) Nsat = maxsignal; FWC Nnoise = min signal; Dark noise + read noise (utan exponering)

43 SNR SNR = Utsignal / brusnivå i utsignal

44 Verkningsgrad Quantum efficiency

45 Öka våglängdsomfånget

46 Bildsensorstorlek Brännvidd Faktorförlängning Bildvinkel

47 Övningsexempel Redogör för parametrarna i den tekniska specifikationen för Kodaks CCD

48 Länkar och litteratur concepts.html Teknisk Fotografi Kjell Carlsson, kap 29