Understanding Infrared Thermography Reading 3

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Changes in the corrections setting for target effective emissivity are also monitored. In addition. digital cameras are available to save visible images in computer compatible format for archiving with corresponding thermograms. For most systems. the displayed temperature readings are based on the assumption that the entire target surface has the same effective emissivity. Some systems. however. allow the assignment of several different emissivities to different areas of the target selected by the operator with the resulting temperature correction. A color scale or gray scale is provided along one edge of the display with temperature shown corresponding to each color or gray level in the selected range. The operator can place one or more spots or crosshairs on the image and the apparent temperature value of that pixel will appear in an appropriate location on the display. The isotherm feature allows the operator to select a temperature band or interval and all areas on the target within that band then appear enhanced in a predetennined gray shade or color hue. Detailed processing and image diagnostics relies on software that allows manipulation and analysis of each pixel in the thermogram prescnting information in a wide variety of qualitative and quantitative forms for the convenience of the user. Some of these capabilities are described in this chapler. Charlie Chong/ Fion Zhang
In addition to the spot measurement capability discussed previously. line profiles may be selected. The analog trace. in X, Y. or both. of the lines on the image intersecting at the selected spot will then appear at the edge of the display. Some systems allow the operator to display as many as seven sets of profiles simultaneously. Profiles of skew lines can also be displayed on some systems. Selected areas on the thermogram in the form of circles, rectangles or point-to-point free forms, can be shifted, expanded. shrunk or rotated or used to blank out or analyze portions of the image. Detailed analysis of the entire image or the pixels within the area can include maximum, minimum and verage values. number of pixels or even a frequency histogram of the values within the area. Color scales can be created from 256 colors stored in the computer. Electronic zoom features allow the operator to expand a small area on the display for closer examination. or to expand the colors for a small measurement range. Autoscale features provide the optimum display settings for any image if selected. Three-dimensional features provide an isometric thermal contour map or thermal profile map of the target for enhanced recognition of thermal anomalies. 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
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Infrared Detector An infrared detec
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Figure 3.2: Response Curves of Vari
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The mercury cadmium telluride (HgCd
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Infrared Optics - Lenses, Mirrors a
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Field of View (FOV) A field of view
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What is IFOV? A measure of the spat
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Instantaneous Field of View (IFOV)
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3.5 Scanning and Imaging When probl
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Line Scanning When the measurement
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Two-dimensional Scanning - Thermal
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Figure 3.5: Optomechanlcally scanne
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Pyroelectric Vidicon Thermal Imager
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Figure 3.6: Typical uncooled infrar
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IRFPA Charlie Chong/ Fion Zhang htt
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3.6 Performance Parameters of Infra
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Performance parameters of qualitati
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Temperature Range Temperature range
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Temperature Sensitivity Temperature
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Speed of Response Speed of response
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Figure 3.7: Instrument speed to res
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Figure 3.8: Instrument field-of-vie
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D ≡ αd D = spot size (approximat
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Output Requirements Output requirem
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Spectral Range Spectral range denot
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Spectrall y selective instrumems us
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Figure 3.9: Spectral response of an
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3.7 Performance Characteristics of
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The total field of view for a line
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Instantaneous Field of View IFOV In
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Recalling! Temperature sensitivity
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IFOV - MTF The 0.35 MTF refers to:
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Fig. 2a. Slit Response Function. Ca
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Minimum Resolvable Temperature Diff
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EXAM score! D=σ∙d IFOV ratio = d
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Charlie Chong/ Fion Zhang
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Answer: D= σ•d, IFOV ration= 1/
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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
Page 253 and 254: Special Purpose Devices Special pur
Page 255 and 256: FLIR- Forward Looking Infrared Char
Page 257 and 258: Typically, the total field of view
Page 259 and 260: Pyroelectric devices have no direct
Page 261 and 262: Figure 3.12: Infrared focal plane a
Page 263 and 264: Infrared focal plane array imager C
Page 265 and 266: Infrared focal plane array imager C
Page 267 and 268: On-board capabilities include isoth
Page 269 and 270: ccc Electron Microscope Image of mi
Page 271 and 272: Platinum Silicide IrFPA 19 t«lU 98
Page 273 and 274: Quantitative IR Image Charlie Chong
Page 275: Quantitative Thermal Measurements S
Page 279 and 280: Stored images can be retrieved, dis
Page 281 and 282: Calibration Accessories Infrared ra
Page 283 and 284: Online printers and plotters are re
Page 285 and 286: Q1. The thermal resolution of an in
Page 287 and 288: Q7. The 3 to 5 μm spectral region
Page 289 and 290: Q13. A line scanner can be used to
Page 291 and 292: Q19. For which of the following app
Page 293 and 294: Q25. Two-color (ratio) pyrometers m
Page 295 and 296: Chapter 4 Operating Equipment and U
Page 297 and 298: ■ Emissivity Differences ∆τ Em
Page 299 and 300: Causes of Real Temperature Changes
Page 301 and 302: Mass Transport Differences (Fluid F
Page 303 and 304: Figure 4.1: An indication of water
Page 305 and 306: Thermal Capacitance Differences ∆
Page 307 and 308: ■ Induced Heating Differences (by
Page 309 and 310: Induced Heating Differences Charlie
Page 311 and 312: ■ Energy Conversion Differences E
Page 313 and 314: Figure 4.3: Catalytic reformer vess
Page 315 and 316: Infrared Thermogram Energy Conversi
Page 317 and 318: Infrared Thermogram Energy Conversi
Page 319 and 320: ■ Combination of Heat Transfer Me
Page 321 and 322: Infrared Thermogram of a running mo
Page 323 and 324: ■ Spectral Considerations in Prod
Page 325 and 326: 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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