Fluke 561s - Manual (Page 10)

561
Users Manual
6
How the Thermometer Works
Infrared thermometers measure the surface temperature of an opaque object. The
Thermometer’s optics sense infrared energy, which is collected and focused onto a detector.
The Thermometer’s electronics then translate the information into a displayed temperature
reading which appears on the display. The laser is used for aiming purposes only.
Operating the Thermometer
The Thermometer turns on when you press the trigger. The Thermometer turns off when no
activity is detected for 7 seconds.
To measure temperature, aim the Thermometer at the target, pull and hold the trigger. Release
the trigger to hold a temperature reading.
Be sure to consider distance-to-spot size ratio and field of view. The laser is used for aiming
only.
Locating a Hot or Cold Spot
To find a hot or cold spot, aim the Thermometer outside the target area. Then, slowly scan
across the area with an up and down motion until you locate the hot or cold spot. See Figure 4.
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Figure 4. Locating a Hot or Cold Spot
Distance and Spot Size
As the distance (D) from the target being measured increases, the spot size (S) of the area
measured by the unit becomes larger. The spot sizes indicates 90 % encircled energy. The
maximum D:S is obtained when the Thermometer is 900 mm (36 in) from the target resulting in
a spot size of 75 mm (3 in). See Figure 5.