For low-temperature applications of radiation thermometry the target's surroundings are often at a comparable temperature to that of the target itself. Thus, when the target is not a blackbody, the potential for large reflection errors is high. This paper discusses two complementary methods that can be used to overcome this reflection error. The first relies on the observation that, regardless of the target's emissivity, the target together with its surroundings are a good approximation to a blackbody. Thus measurements are made with no emissivity compensation. The second method utilises the fact that in low-temperature radiation thermometers the radiance of the detector itself causes an offset. Thermometer manufacturers recognise that in some situations, with the appropriate sequence of emissivity compensation and offset correction, the detector offset can be used to correct for the reflection error due to the surroundings. As a consequence many radiation thermometers are designed to operate in this manner. However, there are distinct regimes where one particular reflection compensation method is more effective than the other. This paper analyses the two methods, gives guidelines on when to use one method over the other, and determines the resulting residual errors
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