A new absolute calibration method for a broad range of light intensities

We introduce a self-consistent absolute calibration method using a photomul tiplier tube (PMT) covering a full dynamic range from a single photon to a macroscopic ambient light intensity. The method is based on the one-photoel ectron counting (OPEC) of the PMT. The one-photoelectron peak can be clearl y identified in the intensity distribution of the PMT output and provides a clear calibration standard. Our method starts from the identification of a single photoelectron peak and is applied all the way up to the mJ/pulse in tensity range. Therefore, the main idea is the accurate determination of th e gain of the PMT, and the major error comes from the gain. Most of the err ors due to environmental variations are cancelled out because we take into account only the ratio of the intensity of the light to that of the one-pho toelectron. The spectral range of the method depends on the photocathode ma terial of the PMT and covers the range from 150 nm to 800 nm.