Improved Transfer Standard Sources for Calibration of Field Spectrometers Used for Earth Observation Applications

摘要

NPL, in conjunction with many NMIs, has been seeking to improve the accuracy of its primary scales of spectral irradiance and radiance. In common with other laboratories this has been done through the use of an ultra-high temperature blackbody characterised using filter radiometers calibrated against a cryogenic radiometer. Whilst such work is of importance to the Earth Observation (EO) community, it is also recognised that of at least equal importance is an improvement in the quality of the scales that are provided to the end user. This paper will describe new transfer standard sources of both spectral radiance and irradiance that have been developed not only to improve accuracy to the end user, but also to provide it in a form that is both robust and convenient to use. For example the radiance source has a spatial non-uniformity of <0.05% over a 50 mm diameter aperture and can maintain its accuracy (<0.3%) for more than 100 hrs of operation.