Except for sources containing small quantities of by-product material, a specific licence is required to obtain or possess light standard sources. The exempt amount of radioactive material in the United States is 100 ÂµCi carbon-14 per source.
A calibration certificate may be delivered with each lot of light standard sources. The document contains specific data about the luminance, the activity content and the wavelength of the phosphor applied. An official certificate is available on request.