BRIGHTNESS PRESENTATION APPARATUS

摘要

PURPOSE:To accurately calibrate brightness, by providing incident and emitting apertures in an integrating sphere coated with a white material on the inner surface thereof and providing a white reflecting plate coated with the same white material at the center of the integrating sphere. CONSTITUTION:A white material having high reflectivity and angle distribution for the distribution of reflected light approximate to cos theta is applied to the inner wall surface of an integrating sphere 1 and the surface of a white reflecting plate 2. The light from a light source 4 is incident to the interior of the sphere 1 from the incident opening part (a) thereof to be diffused and reflected by the back surface of the reflecting plate 2. This light is subjected to multipath reflection by the inner wall surface of the sphere 1 and the reflecting plate 2 to finally irradiate the surface of the reflecting plate 2 uniformly. At this time, the light incident to the reflecting plate 2 is measured by an illuminometer light receiving part 3 and the photoelectric output is thereof serves as the output corresponding to luminous intensity by an implifier 6 while said output is converted to a brightness value by a luminous intensity- brightness converting circuit 7 to be displayed on a display part 8. The reflecting plate 2 is measured by a brightness meter 5 arranged behind an emitting opening part (b) and the output thereof is adjusted so as to become the aforementioned brightness value displayed on the display part 8 or correction coefficient is calculated to calibrate the brightness meter 5.