PURPOSE: To obtain a measuring apparatus enabling attainment of exact standardiza tion by limiting the quantity of light by a diaphragm to be the same as that obtained through paper, when the quantity of light in an air layer is measured.
CONSTITUTION: An apparatus for measuring the characteristic of a sheet-shaped object has a light-sensing element sensing light from a light-projecting part through the sheet-shaped object, and the physical characteristic of the sheet-shaped object is measured on the basis of a signal from the light-sensing element. The apparatus has an upper reflecting plate 30 and a lower reflecting plate 31 disposed on the opposite sides of the sheet-shaped object 3 and a shielding plate 32 disposed between the sheet- shaped object and the lower reflecting plate. The light-projecting part is equipped with a light source 6, a first lens 7 making the light from the light source be a parallel light beam and a second lens 7a limiting hole 30a of the upper reflecting plate is formed projecting hole 30a of the upper reflecting plate is formed to be small in such a degree as not to intercept the light limited by the second lens, in the vicinity of the focus of the light. Besides, a diaphragm 50 adjusting the quantity of light is provided above or below the second lens.
HARA HITOSHI
CHIBA TAKASHI
ISOZAKI KENJI
