User's Manual
Table Of Contents
- 1 Disclaimers
- 2 Safety information
- 3 Notice to user
- 4 Customer help
- 5 Quick Start Guide
- 6 List of accessories and services
- 7 Description
- 8 Operation
- 8.1 Charging the battery
- 8.2 Turning on and turning off the camera
- 8.3 Saving an image
- 8.4 Recalling an image
- 8.5 Deleting an image
- 8.6 Deleting all images
- 8.7 Measuring a temperature using a spotmeter
- 8.8 Measuring the hottest temperature within an area
- 8.9 Measuring the coldest temperature within an area
- 8.10 Hiding measurement tools
- 8.11 Changing the color palette
- 8.12 Working with color alarms
- 8.13 Changing image mode
- 8.14 Changing the temperature scale mode
- 8.15 Setting the emissivity as a surface property
- 8.16 Setting the emissivity as a custom material
- 8.17 Changing the emissivity as a custom value
- 8.18 Changing the reflected apparent temperature
- 8.19 Changing the distance between the object and the camera
- 8.20 Performing a non-uniformity correction (NUC)
- 8.21 Configuring Wi-Fi
- 8.22 Changing the settings
- 8.23 Updating the camera
- 9 Technical data
- 10 Mechanical drawings
- 11 CE Declaration of conformity
- 12 Cleaning the camera
- 13 Application examples
- 14 About FLIR Systems
- 15 Definitions and laws
- 16 Thermographic measurement techniques
- 17 History of infrared technology
- 18 Theory of thermography
- 19 The measurement formula
- 20 Emissivity tables
Theory of thermography
18
where:
W
λb
Blackbody spectral radiant emittance at wavelength λ.
c
Velocity of light = 3 × 10
8
m/s
h Planck’s constant = 6.6 × 10
-34
Joule sec.
k
Boltzmann’s constant = 1.4 × 10
-23
Joule/K.
T Absolute temperature (K) of a blackbody.
λ Wavelength (μm).
Note The factor 10
-6
is used since spectral emittance in the curves is expressed in
Watt/m
2
, μm.
Planck’s formula, when plotted graphically for various temperatures, produces a family of
curves. Following any particular Planck curve, the spectral emittance is zero at λ = 0,
then increases rapidly to a maximum at a wavelength λ
max
and after passing it ap-
proaches zero again at very long wavelengths. The higher the temperature, the shorter
the wavelength at which maximum occurs.
Figure 18.4 Blackbody spectral radiant emittance according to Planck’s law, plotted for various absolute
temperatures. 1: Spectral radiant emittance (W/cm
2
× 10
3
(μm)); 2: Wavelength (μm)
18.3.2 Wien’s displacement law
By differentiating Planck’s formula with respect to λ, and finding the maximum, we have:
This is Wien’s formula (after Wilhelm Wien, 1864–1928), which expresses mathemati-
cally the common observation that colors vary from red to orange or yellow as the tem-
perature of a thermal radiator increases. The wavelength of the color is the same as the
wavelength calculated for λ
max
. A good approximation of the value of λ
max
for a given
blackbody temperature is obtained by applying the rule-of-thumb 3 000/T μm. Thus, a
very hot star such as Sirius (11 000 K), emitting bluish-white light, radiates with the peak
of spectral radiant emittance occurring within the invisible ultraviolet spectrum, at wave-
length 0.27 μm.
#T559828; r. AK/40423/40423; en-US
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