Method for the Measurement of the Total Flux of a Fluorescent Lamp

In the measurement of the total flux of a fluorescent lamp with a physical photometer, the inconstancy of the photometer’s spectral properties and the imperfection of its approximation to the average eye cannot be avoided. To overcome these defects, monochromatic comparison of radiant flux emitted by the fluorescent lamp and the standard lamp is made in a large integrating sphere. The entrance slit of the double monochromator is connected with a window of a 3.5-meter diameter integrating sphere, and the monochromatic light of the lamps is measured with a multiplier phototube whose linearity and stability are known. Besides, uncertainty of the spectral distribution of the standard tungsten lamp produces errors in measured values of luminous flux of fluorescent lamps, but the order of magnitude of these errors is within 0.3%.