Understanding Infrared Thermography Reading 3

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Selecting the infrared scanning system requires matching thermographic equipment performance capabilities to test criteria. To be effective, thermographic equipment used should offer resolution, sensitivity and versatility somewhat beyond that envisioned to be necessary to detect and identify the defects, the thermographer expects to encounter. The most critical of the scanner performance characteristics are (1) minimum resolvable temperature, (2) spatial resolution and (3) scan speed. Figure 5.13 is an example of stimulated thermography that is ideal for the thermographer. Here the deicing mechanism on the wing of a DC·9 aircraft is evaluated. The deicing system also serves as the energizing source and the thermogram indicates areas that are not being heated as cool spots. The warm rings represent the instantaneous effect of the deicing mechanism. Charlie Chong/ Fion Zhang
Figure 5.13: Test of aircraft deicing element showing unheated areas on the wing of a DC-9 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
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Portable Handheld Devices Charlie C
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Temperature sensitivity and readabi
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Hand Held Infrared Module Charlie C
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Note that the laser beam docs not r
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Emissivity set controls, located in
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IR Sensor Module Charlie Chong/ Fio
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IR Sensor Module Charlie Chong/ Fio
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Two-color Pyrometers or Ratio Pyrom
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Phenomena which are non-dynamic in
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Some ratio thermometers use more th
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Infrared Radiometric Microscopes Ch
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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
Page 401 and 402: Excessive heating due to a defectiv
Page 403 and 404: Inductive currents flowing with in
Page 405 and 406: Moisture in Airframes The detection
Page 407 and 408: Process Control and Product Monitor
Page 409 and 410: The differences produced by this co
Page 411 and 412: Night Vision, Seareh, Surveillance,
Page 413 and 414: Thermogram of helicopter taken at n
Page 415 and 416: Aircraft Under IR Trap Charlie Chon
Page 417 and 418: Instruments used for these applicat
Page 419 and 420: 8 to 12 μm spectral region over wh
Page 421 and 422: Animal Studies Body heat allows inf
Page 423 and 424: Injured equine foreleg (left) appea
Page 425 and 426: Work energy is expended by friction
Page 427 and 428: 5.4 Fluid Flow Investigations For s
Page 429 and 430: Figure 1.7: Thermographs of valve (
Page 431 and 432: ■ Building Insulation and Other F
Page 433 and 434: Figures 5.8 and 5.9 illustrate thes
Page 435 and 436: Figure 5.9: Example of air exfiltra
Page 437 and 438: Example of air exfiltration Charlie
Page 439 and 440: ■ Refractory Systems Industrial s
Page 441 and 442: Refractory Thermogram Charlie Chong
Page 443 and 444: ■ Subsurface Discontinuity Detect
Page 445 and 446: Figure 5.11: An example of passive
Page 447 and 448: The equipment necessary to perform
Page 449 and 450: Figure 5.12: Example of active (hea
Page 451: Typical failure modes of the materi
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Page 457 and 458: Figure 5.14: Conceptual sketch of t
Page 459 and 460: In this case. however, the heat pul
Page 461 and 462: Figure 5.15: Erosion/corrosion dama
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Page 465 and 466: When there has been adequate solar
Page 467 and 468: Liquid Level Detection Thermal capa
Page 469 and 470: Unstimulated and Stimulated Approac
Page 471 and 472: Subsurface Discontinuity Detection
Page 473 and 474: 1. A major area of infrared nondest
Page 475 and 476: 5. The diagnostics involved in dete
Page 477 and 478: 9. Thermography has been successful
Page 479 and 480: Appendix A Glossary The following a
Page 481 and 482: Ambient temperature - Temperature o
Page 483 and 484: Figure A-1 Apparent ambient tempera
Page 485 and 486: 13.Blackbody, blackbody radiator -
Page 487 and 488: Alas! Heat Capacity Volumetric = C
Page 489 and 490: 27.Detector, infrared - A transduce
Page 491 and 492: Thermal Effusivity In Thermodynamic
Page 493 and 494: Alas! Exitance = Rodiosity for my A
Page 495 and 496: 45.Frame repetition rate - The time
Page 497 and 498: Thermal Inertia Thermal inertia is
Page 499 and 500: Instantaneous field of View (lFOV)
Page 501 and 502: 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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Understanding Infrared Thermography Reading 3

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