Ir Measurement Notes; Field Of View - Extech Instruments 42570 User Manual

IR Measurement Notes

1. The object under test should be larger than the spot (target) size calculated by the field of view
diagram (printed on the side of the meter and in this guide).
2. Before measuring, be sure to clean surfaces that are covered with frost, oil, grime, etc.
3. If an object's surface is highly reflective, apply masking tape or flat black paint to the surface
before measuring. Allow time for the paint or tape to adjust to the temperature of the surface it is
covering.
4. Measurements are not possible through visibly transparent materials, such as glass.
5. Steam, dust, smoke, etc. can obscure measurements.
6. The meter automatically compensates for deviations in ambient temperature. However, it can
take up to 30 minutes for the meter to adjust to extremely wide changes.
7. To find a hot spot, aim the meter outside the area of interest then scan across (in an up and
down or side to side motion) until the hot spot is located.

Field of View

The meter's field of view is 50:1. For example, if the meter is 50 inches from the target (spot), the
diameter of the target must be greater than 1 inch. Other distances are shown in the field of view
diagram. Measurements should normally be made as close as possible to the 1" spot distance. The
meter can measure from longer distances, but the measurement may be affected by external
sources of light. In addition, the spot size may be so large that it encompasses surface areas not
intended to be measured.
@250cm @100"
5cm 2"
@125cm
@50"
2.5cm
1"
@63cm
@25"
1.25cm 0.5"
7 42570-en-GB_V1.6 12/14