Dissertation - FTP Directory Listing - University of Surrey

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3.2. Sensor characterisationThe Aspect system was used for characterisation tests, every sensor initially required a few weeks toget full functionality and to allow for diagnosis of any problems found during setup. Once thesensors were fully operational characterisation tests were performed. The level of control possiblewith the Aspect system meant a standard set of tests could be performed for any sensor withrelatively few modifications. The general experimental setup is shown in Figure 2.21. Each sensorhad its own modular support circuit boards so switching sensors took only a few minutes. Eachsensor also had its own directory containing settings and files required to run the sensor (seeappendix B). The characterisation test consisted of taking frames of varying illumination from theLED light source over the full range of the sensor. To ensure a good degree of accuracy a set of 200frames were taken at each illumination level (from dark to saturation), from these the first 10 werediscarded to remove any settling effects present. Each test was performed using the green LEDs(546nm) as CMOS sensors are typically most sensitive to the green part of the spectrum. Once theset of files had been taken they were loaded into a per pixel analysis program. This producedperformance parameters on a per pixel basis (appendix C explains the programs operation) and theaverage results.3.2.1. eLeNA testingAs eLeNA contains many different test structures each one had to be individually characterised. Todo this control signals were modified to read out only certain rows and columns allowing regions ofinterest to be set. A region of 34x34 pixels was read out from the centre of each test structure forcharacterisation of each test structure.3.2.2. LAS testingAs there were so many pixels in LAS (~1.8Mpixels) saving full frames would take up a lot of space onthe hard drive this would also have resulted in a slow frame rate of 20fps allowing dark current tobuild up and effect results. For these reasons a smaller region of interest was readout, the region ofinterest was 20rows by the full 1350 columns. The full number of columns was included as thereadout structure meant reducing the number of columns readout resulted in very small gains inreadout speed.38
3.2.2.1. QE investigationIt was found during testing that LAS demonstrated a much lower than expected quantum efficiency.QE was found to be around 20% for the 3 wavelengths available for testing on the Aspect system.The QE was expected to be closer to 60%, the reason for the low QE wasn’t clear but one idea wasthat reflections caused by different reflective indices of the insulating layers on top of the sensorwere causing dips in quantum efficiency at certain wavelengths of incident radiation. If thewavelengths tested were in these troughs then it could explain the low quantum efficiency seen.In order to test this theory LAS would need to be tested with more wavelengths than possible withthe LED light source. A monochromator and halogen light source from the labs previous test systemwere used to provide a wider range of wavelengths. The experimental setup is shown in Error!Reference source not found..OptoDAQSignals from computerIntegrating sphereLAScamerasetupMonochromatorHalogen lampFigure 3.2 Experimental setup for extended quantum efficiency measurementsInitially it was intended to use the Aspect system to run the sensor but it wasn’t possible to fit themonochromator and light source into the black box. So frame capture was performed using anoptoDAQ camera setup along with the previous test system contained in a larger black box. Thehalogen light passes through a monochromator which allows the wavelength to be selected to a highdegree of accuracy. The light then enters an integrating sphere which emits light of uniformintensity over an area of approximately 2cm 2 . Set back 35cm from the integrating sphere is the LAScamera system which hold the sensor and control circuitry. This is linked to an optoDAQ system tocontrol the sensor and grab images. A labVIEW program was written to control the monochomatorand frame grabbing on the optoDAQ.39
Page 2 and 3: ABSTRACTThe characterisation of fou
Page 4 and 5: LIST OF ABBREVIATIONSAPSCCDCDSCMOSD
Page 6 and 7: 2.8.3. FORTIS .....................
Page 8 and 9: CHAPTER 4Figure 4.1 LED uniformity
Page 10 and 11: Over the next 30 years CCDs improve
Page 12 and 13: There are 3 main types of semicondu
Page 14 and 15: 2.2. Photodetectors2.2.1. The Photo
Page 16 and 17: V G < V FB V FB < V G < V T V T < V
Page 18 and 19: Figure 2.5 Cross sectional diagram
Page 20 and 21: 2.3.1.2. Interline transferIn an in
Page 22 and 23: Figure 2.9 NMOS transistor operatin
Page 24 and 25: in three main categories of CMOS se
Page 26 and 27: transistor M SEL is turned on and t
Page 28 and 29: qK = ×cA SF(2.5)Where:K = conversi
Page 30 and 31: 2.4.6. Signal to noise ratioSNR is
Page 32 and 33: When h/ ≫ this equation reduces
Page 34 and 35: The gain functions in this relation
Page 36 and 37: Where: σ (DNTOTAL) is the total no
Page 38 and 39: The Aspect system is a complete tes
Page 40 and 41: The pixel architecture (Figure 2. .
Page 42 and 43: eset, hence reducing kT/C noise. In
Page 44 and 45: Figure 2.28 Readout structure of TE
Page 48 and 49: Once everything was setup and the c
Page 50 and 51: From this it can be seen that for e
Page 52 and 53: 4.2.2. A test structure results:The
Page 54 and 55: values is 493.7 DN. The noise of te
Page 56 and 57: 20,100e-. Finally Figure 4.9 shows
Page 58 and 59: This test structure demonstrates go
Page 60 and 61: 4.2.5. D test structure results:Fig
Page 62 and 63: Of the two variants it appears D2 p
Page 64 and 65: 100Number of pixels1012000 2200 240
Page 66 and 67: As can be seen the plot exhibits so
Page 68 and 69: 100000uy - uy. dark [DN]10000100010
Page 70 and 71: the halogen lamp had to tested with
Page 72 and 73: have an effect it is not great enou
Page 74 and 75: 10000010000uy - uy. dark [DN]100010
Page 76 and 77: temp.var - dark.temp.var [DN]500004
Page 78 and 79: effect of these changes can’t be
Page 80 and 81: 100Number of pixels1015350 5400 545
Page 82 and 83: 10000Linearityuy - uy. dark [DN]100
Page 84 and 85: lower than the standard diode. The
Page 86 and 87: 6. REFERENCES1. http://cerncourier.
Page 88 and 89: 7. APPENDICES7.1. Appendix A: EMVA
Page 90 and 91: 7.2. Appendix B: Aspect quick start
Page 92 and 93: iii)iv)Once you have followed all o
Page 94 and 95: 5. Running idVIEWi) Before running
Page 96 and 97:
a) Taking Measurements with only on
Page 98 and 99:
a) The EMVA Standard takes into con
Page 100 and 101:
7.3. Appendix C: Per pixel analysis
Page 102 and 103:
Plot the gradient of the PTC by dra
Page 104:
The final tab which both the integr
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