J E Martin

TL;DR: In this article, a new electrical-substitution absolute radiometer operating at 5 K, based on a standard commercial helium cryostat, which has been developed at NPL for optical radiant power measurements, is described.

TL;DR: The total radiant exitance of a black body at the temperature of the triple point of water, T$\text{tp}}$ (273.16 K), and at a series of other temperatures in the range from about 233 K (-40 degrees C) to 373 K (100 degrees C), has been measured by using a cryogenic radiometer as discussed by the authors.

TL;DR: In this paper, narrow band filter radiometers have been used to measure the spectral radiance of black bodies held at the melting/freezing points of aluminium, silver and gold with an accuracy of 0.04%.

TL;DR: To substantiate the NPL primary standard cryogenic radiometer as an absolute instrument it has been compared with the cryogen radiometer which was successfully used to determine the Stefan-Boltzmann constant.

TL;DR: In this paper, the NPL total radiation thermometer T-T68 is reported for the temperature range - 130 to + 60°C and tabulated with previous measurements made in the range -40 to +100°C.