month I would like to discuss infrared thermometers. These
are often called "laser thermometers," however,
the laser dot is only for aiming or teasing animals, and it
has nothing to do with temperature measurement or the size
of the area being measured.
are many different types of IR Thermometers. Many are inexpensive
and will do the simple jobs, others are more complex for increasingly
critical tasks, and some are even National Institute of Standards
& Technology certified for accuracy.
infrared thermometers measure the surface temperature of the
subject object. Shiny surfaces or dirt can effect measurements
so checking several areas is a good idea when these conditions
exist. If pointed at a transparent surface such as glass,
the IR Thermometer will measure the surface temperature of
the glass, not the outdoor temperature. All infrared thermometers
work the same way; the internal optics sense emitted, reflected
and transmitted energy from the object being measured and
translate this data into a temperature measurement.
item to consider is the Distance to Spot Size ratio. Most
inexpensive IR Thermometers have a D:S ration of 8 to 1. This
means the area being measured is approximately 1-inch in diameter
at a distance of 8-inches. The spot size increases to 2-inches
when the object is 16-inches from the thermometer and so on.
A key item to remember is the object being measured must always
be larger than the spot size otherwise the temperature measurement
will be skewed by perimeter surfaces that may be different
temperature. As you can see, it is critical to consider spot
size when using an IR Thermometer for accurate measurements.
makes available reasonably priced IR Thermometers for its
customers. Check out the RayTek
MiniTemp. This unit has a D:S ratio of 8:1.
talk next month,
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