IES LS-4-20

Radiometry is the science of the measurement of optical radiation, and is part of the general science of measurement, metrology. Photometry, a special branch of radiometry, is the measurement of radiation accounting for human visual response. This Lighting Science (LS) document describes the various types of photometry and photometric instrumentation, including laboratory and field equipment and measurement types, and instructions for some types of field measurements. However, it does not provide instructions or methodology for performing laboratory tests. For that kind of information, the reader is referred to the IES Lighting Measurement (LM) series of documents.