Light distribution photometry in Japan.

Of the representative distribution photometers constructed in Japan, a large-size photometer without mirrors, a compensation method for the variation in light output of a lamp, and an automatic recording of a sinusoidal isocandela diagram are illustrated. Next, a new idea for integrating the luminous flux of a lamp proposed by Ishii and Muroi and a photometer based on it are explained. The error due to two kinds of light distribution from light sources in the sphere photometer using a light distribution photometer are discussed. Finally, a theory is introduced on the photometric error due to the error in positioning the light source in the light distribution photometer. Application of the theory shows that the error in luminous flux is negligible if reasonable care is taken in positioning the lamp.