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5.2. Using the Thermal Imager
For basic operation follow these steps:
1. Set the function switch to any position.
2. Press the “
IR
” button to switch the thermal imager ON, Target the
object by the thermal imager lens.
3. The display will show the temperature measurement in the upper left
hand corner for the targeted area along with the currently selected
Emissivity value.
4. In the Thermal imaging mode, the laser pointer and display cross hairs
can be used to assist in targeting, these tools can be switched on or off
in the setting menu.
5. In the Thermal imaging mode, the highest temperature will be auto
marked by a red cross, and the lowest temperature will be auto marked
by a blue cross, the two spots can be switched on or off in the setting
menu.
6. In the Thermal imaging mode, the meter continues to operate normally
as a multimeter allowing any of the electrical functions to be used.
7. Press the HOLD Button to hold the thermal image frame, then hold down
the HOLD Button, you will capture the screen and save a bitmap with
measure data into SD card, the saved bitmap later can be analysed by
the PC software or smart phone APPs.
8. The thermal imager’s FOV (Field of view) is 21 by 21 degrees.
9. FOV is the largest area that your imager can see at a set distance.
10. This table lists the horizontal FOV, vertical FOV and IFOV for lens.
Focal Length
Horizontal FOV
Vertical
FOV IFOV
7.5mm
21°
21°
4.53mrad
•
IFOV
(Instantaneous Field of View) is the smallest detail within the FOV
that can be detected or seen at a set distance, the unit is rad, The
formula is this: IFOV = (Pixel Size)/(Lens focal length)
• D:S theoretical (= 1/IFOV theoretical) is the calculated spot size based
on the pixel size of the Thermal Imager detector array and lens focal
length.
Example:
If Thermal Imager uses 9mm lens, because the Pixel size of
detector is 34um.
• Horizontal FOV is 21°, Vertical FOV is 21°, the IFOV is 34um/7.5mm =
4.53mrad; D:S theoretical (=1/IFOV theoretical) = 220:1.
• D:S measure (=1/IFOV measure) is the spot size needed to provide an
accurate temperature measure; Typically D:S measure is 2 to 3 times
smaller than D:S theoretical, which means the temperature measurement
area of the target need to be 2 to 3 times larger than that determined by
the calculated theoretical D:S.
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