Isotech first introduced the Model 988 to assist in relation to the
SARS outbreak during the early 2000s. Used to increase the accuracy of
thermal imagers being used to measure human skin temperature in
temperature screening of applications. It can also be used to check
non-contact clinical thermometers. Following the increased demand in
relation to COVID-19, Isotech have now introduced an updated blackbody
source, Model 989.
Model 989 has the same performance as the earlier 988 but is smaller
and has two easy mounting points fitted allowing for ease of use. When
used in conjunction with IR cameras, the device can easily be suspended
from above or below using standard tripod mounting brackets. The
upgraded controller that is used can either be locked to a single
temperature or it can be adjusted over a new wider temperature range of
20°C to 50°C. Model 989 also has a PC interface fitted as standard that
allows the temperature to be both monitored and adjusted from a PC.
This Model 989 blackbody source meets the demand for a simple, cost
effective but high accuracy device for the calibration of thermal
imagers and infrared thermometers that are used at temperatures around
that of the human body. Unlike heat only devices, this model uses a
solid state thermoelectric heat pump so that the block can be both
cooled and heated. This brings two benefits, the blackbody can maintain
its set point in high ambient temperature conditions and it can also
operate below the ambient temperature.
Response time is very fast, typically less than five minutes to
achieve the required temperature (see graphs). The Model 989 can be used
either horizontally or vertically. The device features a high
emissivity ridged plate that is 70mm in diameter. The temperature of the
plate can be set from 20°C to 50°C to a resolution of 0.01°C.
To reduce sensitivity to air draughts and ambient temperature
effects, a stainless steel tube can be fitted in front of the plate with
evaluation showing this has advantages over an open plate design. The
longer tube length is 210mm while the shorter tube is 40mm long and is
particularly useful for checking medical thermometers. For applications
where the unit is used at a single fixed temperature, e.g. 38°C, the set
temperature on the controller can be locked to prevent accidental
change or tampering. The operating unit can be changed from Celsius to
Fahrenheit.