Distance And Measuring Spot Size; Emission Factor - Trotec BP20 Manuel D'utilisation

The BP20 has a dual laser, which automatically displays the size
of the measurement spot. The distance between the two laser
beams corresponds to the diameter of the measuring spot.
12.5 mm spot
@ 150 mm
To deactivate this, press the laser On/Off button again.The laser
symbol goes out.
For measurements in the darkness the background illumination
can be activated and deactivated with the background illumination
button .

8. Distance and measuring spot size

(Distance-to-spot-ratio D:S)
To achieve accurate measuring results the target must be
larger than the measuring spot of the infrared thermometer.
The determined temperature is the average temperature of the
measured surface. The smaller the target the shorter the distance
from the infrared thermometer must be. The exact measuring
spot size can be taken from the diagram.
This is also printed on the instrument. For accurate measurements,
the target must be at least twice as big as the measuring spot.
B - 5

9. Emission factor

The emission factor is a value used to describe the energy
radiation characteristic of a material. The higher this value,
the higher the capacity of the material to emit its own thermal
radiation, without the influence of reflections.
Metal surfaces or glossy materials have a low emission factor
and therefore give inaccurate measured values. Please take this
into account when using the infrared thermometer.
For compensation the surface of glossy parts can be covered
by matt adhesive tape or matt-black paint. The instrument
cannotmeasure through transparent surfaces such as glass.
Instead it measures the surface temperature of the glass.
Many organic materials and surfaces have an emission factor of
approx. 0.95. A table showing the emission factors of various
materials can be found in chapter 15.
The infrared thermometers have a function (see chapters 10)
which enables adjustment of the emission factor within a range
from 0.10 to 1.00 µm so that exact measurements can be obtai-
ned for various materials.
Operating Manual – Laser-Pyrometer