Dr Blevin has made outstanding contributions to precision metrology in the fields of optical radiometry and photometry. His research has greatly increased the accuracy attainable in measurements of radiant power. In realizing Australia's photometric units he has demonstrated major advantages in using detector-based radiometric techniques instead of the traditional primary standard of light. As a result the unit of luminous intensity, the candela, which is one of the seven SI base units, has been radically redefined and related numerically to the watt. Sixteen national standards laboratories, including all the major ones, are now realizing the candela according to its new definition.