IMPAC pyrometer IGA 15 plus
8
4.4
Spot size
The size of the measuring spot of the pyrometer and with that the minimum size of the measuring
object is dependent on the distance. The smallest spot size of 4 mm in diameter is achieved only
in a measuring distance of 800 mm. The spot is decreasing if the distance to the measuring object
is decreasing of increasing from 800 mm.
A spot size table is printed on the right side of the pyrometer corresponding to the below shown
spot size diagram.
Smallest objects with only 1.25 mm diameter can be measured with the additional close-up lens
(optional accessory).
Note:
The pyrometer can measure objects at any distance but the object has
to be bigger or at least as big as the spot size of the pyrometer in the
measuring distance.
For longer measuring distances than 800 mm the size of measuring spot can
be calculated approximately with the following equation:
M = (0.019 x a) - 11
M = spot size in mm
a = measuring distance in mm
With close-up lens (optional):
If using the close-up lens, the emissivity setting of the instrument (EMI) has to
be corrected with the following factor (emissivity see
):
EMI = 0.92 x EMI
object
For longer measuring distances than 250 mm with the close-up lens the size
of measuring spot can be calculated approximately with the following equa-
tion:
M = (0.05 x a) - 11
M = spot size in mm
a = measuring distance in mm
Spot size M [mm]
Measuring distance a [mm]
0
400
7.5
4
800
11
1500
17
Measuring distance a [mm]
Spot size M [mm]
0
11
250
125
500
6.1 1.25
13.5
