Understanding Infrared Thermography Reading 3

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MWIR OR LWIR? For general purpose use and for measuring cooler targets cooler than about 500 °C (932 °F). most manufacturers of radiation thermometers offer instruments operating in the 8 to 14 μm atmospheric window. For dedicated use on hotter targets. shorter operating wavelengths are selected. usually shorter than 3 μm. One reason for choosing shorter wavelengths is that this enables manufacturers to use commonly available and less expensive quartz and glass optics, which have the added benefit of being visibly transparent for more convenient aiming and sighting. Another reason is that estimating emissivity incorrectly will result in smaller temperature errors when measurements are made at shorter wavelengths. Thermographers have learned that a good general rule to follow, particularly when dealing with targets of low or uncertain emissivities, is to work at the shortest wavelengths possible without compromising sensitivity or risking susceptibility to reflections from visible energy sources. Charlie Chong/ Fion Zhang
3.7 Performance Characteristics of Scanners and Imagers Because an infrared thermogram consists of a matrix of discrete point measurements, many of fhe performance parameters of infrared thermal imager are the same as those of radiation thermometers. The output of an infrared line scanner can be considered as one line of discrete point measurements. The parameters of temperature range, absolute accuracy. repeatability, sensor environment and spectral range are esscntially the same for radiation thermometers, line scanners and imagers. Others are derived from or are extensions of radiation thermometer performance parameters. Qualitative thermal imagers (also called thermal viewers) differ from quantitative thermal imagers (also called imaging radiometers) in that thermal viewers do not provide temperature or thermal energy measurements. For thermographers requiring qualitative rather than quantitative thermal images, therefore, some performance parameters are unimportant. Charlie Chong/ Fion Zhang
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Infrared Thermal Testing Reading II
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Infrared Thermography ~-- ... ... .
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Infrared Thermography Charlie Chong
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See Through & Fun Thermal Camera Ex
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How to see through clothing 2 I'
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Apache IR Thermal Weaponry ■ http
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Charlie Chong/ Fion Zhang
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Greek alphabet Letter Name Sound An
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Greek letter l fl 0 I1 p u w Charli
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SGuide-IRT Content Part 1 of 2 ■
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1.1 Introduction to Principles & Th
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The infrared thermal imaging equipm
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The three modes of heat transfer ar
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The three modes of heat transfer ar
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Temperature and Temperature Scales
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Boston Tea Party - New governances
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The Mighty Fahrenheit & ⅝”, Eng
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Absolute zero is equal to - 273.16
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The Fourier conduction Law expresse
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The Fourier conduction Law ( One di
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Convective Heat Transfer Convective
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Figure 1.2: Convective heat flow T
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Newton's cooling law defines the co
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Radiative Heat Transfer Radiative h
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Figure 1.4: Infrared radiation leav
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Thermal infrared radiation impingin
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Reflections off Specular and Diffus
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Reflections off Specular and Diffus
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Radiant Energy Related to Target Su
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The Stefan-Boltzmann law: W= σƐT
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Figure 1.6: Typical blackbody distr
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1.4 Practical Infrared Measurements
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Characteristics of the Target Surfa
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Referring back to Figure 1.5, the t
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Characteristics of the Transmitting
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Figure 1.10; Transmission of 10m (3
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Figure 1.11: Transmission, absorpti
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Figure 1.12: Transmission curves of
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Chapter 1 Review Questions Q&A 1. b
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Q4. Heat can only flow in the direc
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Q10. The follow ing spectral band i
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Q16. In forced convection, the boun
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Q22. In the 8 to 14 μm spectral re
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2.1 Materials Characteristics A kno
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For an emissivity reference table t
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Errors because of point source refl
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View Angle The angle between the in
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Thermal Conductivity Thermal conduc
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Thermal Diffusivity As in emissivit
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Partial 2.1 Table 2.1: d i'ffusivit
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Partial Table 2.2 Table 2.2: Normal
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Chapter 2 Review Questions Q&A 1. c
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4. When measuring the temperature o
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10. A highly textured surface is sa
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3.1 Thermal Instrumentation Overvie
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Thermopile- Thermoelectric Seebeck
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What is a IR Thermopile? (non-conta
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IR Thermopile Quad Sensor (non-cont
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Thermocouple A thermocouple is a te
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Bourdon Gas Thermometers 5 f\G.3 0
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Liquid Crystal Thermometer A liquid
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Bimetallic Thermometers Dial Spiral
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In RTD devices; Copper, Nickel and
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Platinum Resistance Thermometer Cha
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RTD Materials Different materials u
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Operations of RTD An RTD takes a me
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Benefits of Thin Film RTD There are
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Thermistor +V r===~ Op A p V to A I
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3.2 Contacting Thermal Measuring De
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■ Thermocouple Thermocouples are
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■ Thermistors Thermistors arc als
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3.3 Optical Pyrometers Optical pyro
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Pyrometer A pyrometer is a type of
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Brightness Pyrometers -Wien’s Law
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The processing electronics unit amp
Page 151 and 152: Infrared Detector An infrared detec
Page 153 and 154: Figure 3.2: Response Curves of Vari
Page 155 and 156: The mercury cadmium telluride (HgCd
Page 157 and 158: Infrared Optics - Lenses, Mirrors a
Page 159 and 160: Field of View (FOV) A field of view
Page 161 and 162: What is IFOV? A measure of the spat
Page 163 and 164: Instantaneous Field of View (IFOV)
Page 165 and 166: 3.5 Scanning and Imaging When probl
Page 167 and 168: Line Scanning When the measurement
Page 169 and 170: Two-dimensional Scanning - Thermal
Page 171 and 172: Figure 3.5: Optomechanlcally scanne
Page 173 and 174: Pyroelectric Vidicon Thermal Imager
Page 175 and 176: Figure 3.6: Typical uncooled infrar
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Page 179 and 180: 3.6 Performance Parameters of Infra
Page 181 and 182: Performance parameters of qualitati
Page 183 and 184: Temperature Range Temperature range
Page 185 and 186: Temperature Sensitivity Temperature
Page 187 and 188: Speed of Response Speed of response
Page 189 and 190: Figure 3.7: Instrument speed to res
Page 191 and 192: Figure 3.8: Instrument field-of-vie
Page 193 and 194: D ≡ αd D = spot size (approximat
Page 195 and 196: Output Requirements Output requirem
Page 197 and 198: Spectral Range Spectral range denot
Page 199 and 200: Spectrall y selective instrumems us
Page 201: Figure 3.9: Spectral response of an
Page 205 and 206: The total field of view for a line
Page 207 and 208: Instantaneous Field of View IFOV In
Page 209 and 210: Recalling! Temperature sensitivity
Page 211 and 212: IFOV - MTF The 0.35 MTF refers to:
Page 213 and 214: Fig. 2a. Slit Response Function. Ca
Page 215 and 216: Minimum Resolvable Temperature Diff
Page 217 and 218: EXAM score! D=σ∙d IFOV ratio = d
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Page 221 and 222: Answer: D= σ•d, IFOV ration= 1/
Page 223 and 224: Break Time - Kenya Coffee Picker Ch
Page 225 and 226: Portable Handheld Devices Charlie C
Page 227 and 228: Temperature sensitivity and readabi
Page 229 and 230: Hand Held Infrared Module Charlie C
Page 231 and 232: Note that the laser beam docs not r
Page 233 and 234: Emissivity set controls, located in
Page 235 and 236: IR Sensor Module Charlie Chong/ Fio
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Page 239 and 240: Two-color Pyrometers or Ratio Pyrom
Page 245 and 246: Phenomena which are non-dynamic in
Page 247 and 248: Some ratio thermometers use more th
Page 249 and 250: Infrared Radiometric Microscopes Ch
Page 251 and 252: Line Scanners Line scanners are div
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Special Purpose Devices Special pur
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FLIR- Forward Looking Infrared Char
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Typically, the total field of view
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Pyroelectric devices have no direct
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Figure 3.12: Infrared focal plane a
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Infrared focal plane array imager C
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Infrared focal plane array imager C
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On-board capabilities include isoth
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ccc Electron Microscope Image of mi
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Platinum Silicide IrFPA 19 t«lU 98
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Quantitative IR Image Charlie Chong
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Quantitative Thermal Measurements S
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In addition to the spot measurement
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Stored images can be retrieved, dis
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Calibration Accessories Infrared ra
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Online printers and plotters are re
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Q1. The thermal resolution of an in
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Q7. The 3 to 5 μm spectral region
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Q13. A line scanner can be used to
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Q19. For which of the following app
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Q25. Two-color (ratio) pyrometers m
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Chapter 4 Operating Equipment and U
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■ Emissivity Differences ∆τ Em
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Causes of Real Temperature Changes
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Mass Transport Differences (Fluid F
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Figure 4.1: An indication of water
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Thermal Capacitance Differences ∆
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■ Induced Heating Differences (by
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Induced Heating Differences Charlie
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■ Energy Conversion Differences E
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Figure 4.3: Catalytic reformer vess
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Infrared Thermogram Energy Conversi
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Infrared Thermogram Energy Conversi
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■ Combination of Heat Transfer Me
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Infrared Thermogram of a running mo
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■ Spectral Considerations in Prod
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Infrared Thermogram Charlie Chong/
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Infrared Thermogram ..... " I Charl
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Figure 4.5: Spectral selectivity fo
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Figure 4.7: temperature thermogram
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Figure 4.8 shows the transmission s
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Figure 4.9: Measuring temperature o
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IR Filter Charlie Chong/ Fion Zhang
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Figure 4.10: Line scanner for conti
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Preparation of Equipment for Operat
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If the instrument is out of cal ibr
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The batteries mentioned on the miss
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Comments: ■ ■ ■ Thermal resol
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Figure 4.11 : Test configuration fo
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3. Reduce the ΔT until the image i
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■ Imaging Spatial Resolution Imag
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A sample setup is illustrated in Fi
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5. If the modulation transfer funct
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Figure 4.13: Test configuration for
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4. Open slit until V meas = V max .
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■ Learning the Startup Procedure
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■ Setting the Correct Effective E
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Figure 4.14: Test configuration for
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■ Measuring and Reporting Tempera
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■ Recognizing and Avoiding Reflec
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■ Measuring the Appropriate Backg
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■ Temperature Differences Between
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■ Liquid and Compressed Gases Som
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Dewar Flask for LN Loosely fitting
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■ Electrical Safety Failure to re
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Table 4.1: Electric shock current t
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4.4 Record Keeping Keeping thorough
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Easily accessible and easily unders
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Q1. Apparent but not real temperatu
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Q5. The higher the temperature of a
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Q9. Differential thermography can b
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5.1 Overview of Applications Becaus
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Electrical Applications Electrical
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High electrical resistance is the m
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Excessive heating due to a defectiv
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Inductive currents flowing with in
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Moisture in Airframes The detection
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Process Control and Product Monitor
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The differences produced by this co
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Night Vision, Seareh, Surveillance,
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Thermogram of helicopter taken at n
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Aircraft Under IR Trap Charlie Chon
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Instruments used for these applicat
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8 to 12 μm spectral region over wh
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Animal Studies Body heat allows inf
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Injured equine foreleg (left) appea
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Work energy is expended by friction
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5.4 Fluid Flow Investigations For s
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Figure 1.7: Thermographs of valve (
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■ Building Insulation and Other F
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Figures 5.8 and 5.9 illustrate thes
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Figure 5.9: Example of air exfiltra
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Example of air exfiltration Charlie
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■ Refractory Systems Industrial s
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Refractory Thermogram Charlie Chong
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■ Subsurface Discontinuity Detect
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Figure 5.11: An example of passive
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The equipment necessary to perform
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Figure 5.12: Example of active (hea
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Typical failure modes of the materi
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Figure 5.13: Test of aircraft deici
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DC - 9 Charlie Chong/ Fion Zhang
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Figure 5.14: Conceptual sketch of t
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In this case. however, the heat pul
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Figure 5.15: Erosion/corrosion dama
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737 aircraft Charlie Chong/ Fion Zh
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When there has been adequate solar
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Liquid Level Detection Thermal capa
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Unstimulated and Stimulated Approac
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Subsurface Discontinuity Detection
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1. A major area of infrared nondest
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5. The diagnostics involved in dete
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9. Thermography has been successful
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Appendix A Glossary The following a
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Ambient temperature - Temperature o
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Figure A-1 Apparent ambient tempera
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13.Blackbody, blackbody radiator -
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Alas! Heat Capacity Volumetric = C
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27.Detector, infrared - A transduce
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Thermal Effusivity In Thermodynamic
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Alas! Exitance = Rodiosity for my A
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45.Frame repetition rate - The time
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Thermal Inertia Thermal inertia is
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Instantaneous field of View (lFOV)
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Laser pyrometer - Laser pyrometer -
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Figure 3.2: Response Curves of Vari
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Compare: Minimum resolvable tempera
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86.Radiation rererenee source - A b
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101. Sector - For a line scanner, a
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113. Subtense, angular - The angula
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121. Thermal wave imaging - A term
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125. Thermogram - A thermal map or
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Appendix B Cost Benefit Determinati
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Although the calculations are quite
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96 ASNT Level Ill Study Guide: Infr
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Appendix C, Commonly Used Infrared
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Appendix C, Commonly Used Infrared
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Peach - 我爱桃子 Charlie Cho
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Good Luck Charlie Chong/ Fion Zhang
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