Model No. PS-2148
Usage Notes
5
®
temperature, allow the detector to cool between each measurement by
moving it away from all hot objects. Then place the sensor near the
object to be measured and monitor the detector temperature as it
increases. Record the intensity when the detector temperature reaches a
certain value.
Alternatively, you can mount the shutter on the sensor and control the
temperature by opening and closing it.
Non-contact Temperature Sensor Simulation
Based on data collected by the IR sensor, and a calibration constant,
you can calculate the temperature of an object.
If the target object approximates a blackbody, then the voltage of the
thermopile is
V
=
k
(
T
s
4
-
T
d
4
)
Where
k
is a constant that you will determined empirically using an
object of known temperature.
You must also know the temperature of the active area of the detector,
T
d
. The embedded thermistor does not measure
T
d
directly; rather it
measures the temperature of the opposite side of the thermopile
(
T
d
-
∆
T
). However, since
∆
T
is always much less than
T
d
(measured in
Kelvin), the thermistor temperature is a good approximation of
T
d
.
*
The constant
k
depends on several factors unique to each measurement
setup including the properties of the particular sensor used, deviation of
the target surface from an ideal blackbody, and any intervening
medium such as air. For more accurate results, the value of
k
should be
empirically determined with an object of known temperature that is
similar to the objects of unknown temperature that you intend to
measure.
For the temperature calibration procedure you will need an object of
variable temperature, of which you can make a direct temperature
measurement. A cup of hot water is a convenient object. Ideally it
should have a matte surface so that its emissivity is close to 1.
You will also need a temperature sensor to measure the temperature
directly. The PASCO Fast-response Probe (PS-2135) works well
because it responds quickly to small changes. Use the probe with a
PS-23125 Temperature sensor or any other PASPORT sensor that
supports external probes; or connect the probe directly to the
temperature port of the Xplorer GLX interface.
Place the IR sensor close to the cup (but not touching) so that the
surface of the cup fills the sensor’s entire field of view. In this way the
surface is seen as an infinite plane, and the distance between the object
*To make the detector
temperature visible in
DataStudio, go the
Experiment Setup
window and select
Temperature with units of
K.
This measurement is the
temperature of the
detector. Do not confuse
it with the temperature of
the target object.
Summary of Contents for PASPORT PS-2148
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