4. Push the navigation pad to confirm and exit the menu mode.
11.6
Changing the measurement parameters
For accurate measurements, it is important to set the measurement parameters:
•
Emissivity
.
•
Reflected temperature
.
•
Object distance
.
•
Atmospheric temperature
.
•
Relative humidity
.
•
External IR window compensation
.
Emissivity
is the most important measurement parameter to set correctly. If the
Emissivity
is set to a low value, the
Reflected temperature
also becomes important. The parameters
Object distance
,
Atmospheric temperature
, and
Relative humidity
are relevant for longer
distances. The
External IR window compensation
must be activated if a protective win-
dow or external lens is used.
You can set the measurement parameters globally. You can also change the
Emissivity
,
Reflected temperature
, and
Object distance
parameters locally for a measurement tool.
For more information, see section 13.5
Changing the measurement parameters
11.7
Performing a non-uniformity correction
(NUC)
11.7.1
General
When the thermal camera displays
Calibrating...
it is performing what in thermography is
called a ”non-uniformity correction” (NUC). An NUC is
an image correction carried out by
the camera software to compensate for different sensitivities of detector elements and
other optical and geometrical disturbances
3
. For more information, see section 27
.
An NUC is performed automatically, for example at start-up, when changing a measure-
ment range, or when the environment temperature changes.
You can also perform an NUC manually. This is useful when you have to perform a critical
measurement with as little image disturbance as possible. You may, for example, want to
perform a manual calibration just before you start recording a video sequence.
11.7.2
Performing an NUC manually
To perform a manual NUC, push and hold down the image archive button
for more
than 2 seconds.
Note
You can also assign the function
Calibrate
to the one of the programmable but-
tons. For more information, see section 7.11
11.8
Hiding all overlay
The camera overlay consists of overlay graphics and image overlay information. The
overlay graphics include items such as measurement tool symbols, result tables, and
status icons. The image overlay information, which you activate on the
Settings
menu,
provides additional information such as the date, emissivity, and atmospheric tempera-
ture. For more information, see section 6.5.6
.
#T810253; r. AL/84068/84441; en-US
54
3. Definition from the European standard EN 16714-3:2016, Non-destructive Testing—Thermographic Testing—
Part 3: Terms and Definitions.
