JPS5555230A - Method of measuring veiling glare rate - Google Patents

Abstract

PURPOSE:To enable the compensation of measurement when the luminous intensity of a background image differs from that of a black linear image in a measuring position and to raise the accuracy of the measurement, by providing a reference position on the image surface of an optical measuring system separately from the measuring position. CONSTITUTION:Light receivers 1-N are juxtaposed at such a spacing that they are not simultaneously covered with a black linear image B. One of the light receivers is fixedly used as a reference position light receiver. The change in the output of each measuring position light receiver corresponds to IS that in the luminous intensity in the measuring position. The change in the output of the reference position light receiver corresponds to that Ir in the luminous intensity in the reference position. The value Is(t2) of the change Is at time t2 shows the luminous intensity at the time when the measuring position is totally covered with the black linear image B. The luminous intensity of a background image is shown by a value Is(t1) at the time t1 when each of the measuring position and the reference position is not affected by the black linear image B. As a result, the accuracy of measurement of veiling glare rate is not affected by the fluctuation in the brilliance of a background illumination system and is therefore raised.