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APPENDIX I
The OS730K’s field of view
HOW TO MAKE ACCURATE IR MEASUREMENTS
The OS730K has a distance-to-spot (D:S) ratio of 30:1. This means that the target area
(spot) whose infrared radiation (temperature) is being measured increases in diameter
by 1 inch for every 30 inches you move
away
from the target. Conversely, the diameter
of the target area measured decreases by 1 inch for every 30 inches you move
closer
to the target.
All IR thermometers (IRTs), including the OS730K, take the
average
temperature of all
objects within a circular
target area (spot)
. Although the distance “D” in the D:S ratio is
defined as a linear value and the “S” defines the diameter of the spot (see above figure),
the critical parameter is the
target area
. Depending on the distance to the target (the
object whose temperature you want to measure), the target area may include both the
target and background objects near or behind the thermometer’s field of view, which
defines the target area or spot.
13
S
inches
mm
D
D:S=30:1
25@750 50@1500
1@30
2@60
3@90
75@2250