Analysis of 320X240 uncooled microbolometer focal plane array ...

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CHAPETER 2UNCOOLED MICROBOLOMETER FOCAL PLANE ARRAY2.1 Basic Theory2.2.1 General AnalysisThe bolometer has been in existence for a while. It is a radiation absorbing device whichmeasures the temperature change due to resistance change in a material from the heatingeffect of the absorbed radiation. Bolometers are power absorbing devices capable ofdetecting radiation of all wavelengths. One of the application of the bolometer ismicrowave power measurement where it is usually placed within a microwave waveguideto measure average power. Other applications include power measurement in the audioand radio frequency range.The most simplest form of bolometer is a short piece of wire. When a piece ofwire is radiated with a source, it will heat up due to absorption of radiation. Theabsorption will cause temperature of the wire to rise, which cause the resistance of thewire to change. The change in the resistance is translated into voltage or current which isproportional to the temperature change.Figure 2.1 shows a simple model of a bolometer. A mass with thermalcapacitance of C is connected to the supporting structure through narrow path withthermal conductance of G. In the case of microbolometer, the thermal conductance pathis combined with the electrical conduction path to the readout electronics.6
Figure 2.1 Simplified bolometer structure.A mathematical model of bolometer is given in reference [7]. Consider abolometer system shown in Figure 2.1. The bolometer material has a heat capacity of Cand the support structure has a thermal conductance of G. The change in energy, Ac, ofthe material is proportional to the change in the temperature T. The proportionalityconstant is the heat capacity of the material. The equation is given byAs = CAT . (2.1)The rate of heat flow d(Ae) is proportional to the change in temperature AT with Kdtbeing the proportionality constant and is given by Equation 2.2.
Page 1 and 2: Copyright Warning & RestrictionsThe
Page 3 and 4: ABSTRACTANALYSIS OF 320X240 UNCOOLE
Page 6 and 7: APPROVAL PAGEANALYSIS OF 320X240 UN
Page 8 and 9: This thesis is dedicated tomy famil
Page 10 and 11: TABLE OF CONTENTSChapterPage1 INTRO
Page 13 and 14: CHAPTER 1INTRODUCTIONIn recent year
Page 17: 5radiation (LWIR) between 811m to 1
Page 21 and 22: 9The first function of the right ha
Page 23 and 24: 11corresponding to T 1 . With radia
Page 25 and 26: 13then the transient term goes to z
Page 27 and 28: 15The signal voltage (Eauation 2.26
Page 29 and 30: 172.2.3 NoiseThe detection capabili
Page 31 and 32: 19F is the f/# of the optics, VN is
Page 33 and 34: 21To obtain the temperature fluctua
Page 35 and 36: 23provide protection against detect
Page 37 and 38: ZE1 L4t46LII C. 10 aft( IL.The UFPA
Page 39 and 40: 27reflection (AR) coated Ge window
Page 41 and 42: 29170 synchronization standard sign
Page 43 and 44: 31amplified and integrated detector
Page 45 and 46: 33processing module by a scan conve
Page 47 and 48: Figure 3.3 UFPA camera platform.35
Page 49 and 50: 37high mechanical strength as shown
Page 51 and 52: Unlike the photon sensors, the micr
Page 53 and 54: 414.2 The Controller DesignThe cont
Page 55 and 56: 43performed at Inframetrics to dete
Page 57 and 58: 45c) Heating of the TEC without hea
Page 59 and 60: 47[(RiR2C1)s + — (R1 + R2) 4.1( )
Page 61 and 62: 49The third amplifier stage has the
Page 63 and 64: t 1
Page 65 and 66: 53c) T showing the response time of
Page 67: REFERENCES1. R. A. Wood, "Uncooled

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