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FLIR E6-XT User Manual

FLIR E6-XT
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Thermographic measurement
techniques
12
12.1 Introduction
An infrared camera measures and images the emitted infrared radiation from an object.
The fact that radiation is a function of object surface temperature makes it possible for
the camera to calculate and display this temperature.
However, the radiation measured by the camera does not only depend on the tempera-
ture of the object but is also a function of the emissivity. Radiation also originates from
the surroundings and is reflected in the object. The radiation from the object and the re-
flected radiation will also be influenced by the absorption of the atmosphere.
To measure temperature accurately, it is therefore necessary to compensate for the ef-
fects of a number of different radiation sources. This is done on-line automatically by the
camera. The following object parameters must, however, be supplied for the camera:
The emissivity of the object
The reflected apparent temperature
The distance between the object and the camera
The relative humidity
Temperature of the atmosphere
12.2 Emissivity
The most important object parameter to set correctly is the emissivity which, in short, is a
measure of how much radiation is emitted from the object, compared to that from a per-
fect blackbody of the same temperature.
Normally, object materials and surface treatments exhibit emissivity ranging from approx-
imately 0.1 to 0.95. A highly polished (mirror) surface falls below 0.1, while an oxidized
or painted surface has a higher emissivity. Oil-based paint, regardless of color in the visi-
ble spectrum, has an emissivity over 0.9 in the infrared. Human skin exhibits an emissiv-
ity 0.97 to 0.98.
Non-oxidized metals represent an extreme case of perfect opacity and high reflexivity,
which does not vary greatly with wavelength. Consequently, the emissivity of metals is
low only increasing with temperature. For non-metals, emissivity tends to be high, and
decreases with temperature.
12.2.1 Finding the emissivity of a sample
12.2.1.1 Step 1: Determining reflected apparent temperature
Use one of the following two methods to determine reflected apparent temperature:
#T559828; r. AP/56791/57153; en-US
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FLIR E6-XT Specifications

General IconGeneral
Accuracy±2°C or ±2% of reading
Field of View45° × 34°
Weight0.575 kg (1.27 lb)
Image Frequency9 Hz
Dimensions244 × 95 × 140 mm (9.6 × 3.7 × 5.5 in)
Spectral Range7.5 – 13 µm
Operating Temperature Range-15°C to 50°C (5°F to 122°F)
Storage Temperature Range-40°C to 70°C (-40°F to 158°F)
Water and Dust ResistanceIP54
Resolution240 × 180 pixels
Thermal Sensitivity<0.06°C
Temperature Range-20°C to +550°C
Display3.0 in 320 × 240 color LCD
Image ModesThermal, MSX, Picture-in-Picture
Battery Life4 hours
Digital Camera640 x 480 pixels
File FormatRadiometric JPEG
Battery TypeRechargeable Li-ion battery
ConnectivityWi-Fi, USB

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