Standards for photometry.

A survey is given of the standards used in photometry and spectroradiometry. After an introduction in Sec. I, the candela and lumen standards are discussed in Sec. II. Some problems related to heterochromatic photometry and the changes in the IPTS are mentioned in Secs. II.B and II.C, respectively. Section III deals with standards for spectroradiometry-the tungsten strip lamp, the anode of the carbon arc, and the high pressure xenon arc-and also with some irradiance standards. A comparison of photometric and radiometric standards is given in Sec. IV. It is concluded that with the present standards an accuracy of 1% is hardly obtainable.