Blackbody Source Model

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.