Voltmaster IRT 1 Manuel D'utilisation page 26

Functions
MODE button
By pressing the button MODE, switching can be carried out between the
different measurement functions:
"MIN"
"MAX"
Indication of the Min and Max values is shown on the main display.
Target laser
With the laser switched on, the laser point points to the approximate centre of
the measurement area. This makes it easier to make exact measurements.
To activate the laser, with the instrument switched on, press the "Laser
symbol button" until the laser symbol appears on the LCD display. If the
temperature measurement button is now pressed, the laser beam now
indicates the approximate centre of the measurement surface. For
deactivation, with the instrument switched on, press the "Laser symbol
button" until the laser symbol goes off.
Size of measurement area – distance to Spot Ration (D/S)
In order to attain more accurate measurement results, the measurement
object must be greater that the measurement area of the infrared
thermometer. The temperature determined is the average temperature of the
area measured. The smaller the measurement object, the shorter the
distance must be to the infrared thermometer. For the exact size of the
measurement surface, refer to the following diagram. This is also stamped
on the instrument.
For accurate measurements, the measurement object should be
a minimum of double so large as the measurement surface!
26
Indication of the lowest temperature value during the
measurement
Indication of the highest temperature value during the
measurement