In this chapter the basic principles of temperature, its definition and measurement are given. Beginning with a brief outline of the fundamental principles, the reader is introduced to the concept of thermodynamic temperature and some of the primary means of its determination. The requirement for a defined scale is explained and a brief historical outline of temperature scales is given including a description of the current temperature scale, the International Temperature Scale of 1990 (ITS 90). Easy access to that scale, in the context of radiation thermometry, is the concern of the next section with the issues of calibration, traceability and accreditation addressed. This is followed by a discussion of how to determine uncertainties in temperature measurement with the emphasis firmly on non-contact thermometry. The chapter concludes with a forward look, discussing possible approaches that could lead to better non-contact thermometry scale realisation and dissemination in the future.
Radiometric Temperature Measurements and Applications