Eastman-Kodak Company

James M Cicchiello

Tomi Lahcanski

Apparatus and method are described for determining the transmission factor or the density of a translucent element, such as an optical filter, using the cosine-to-the-fourth law. The apparatus includes a source of light of constant color and intensity. A detector is mounted on a track for movement along rectilinear path with the plane of the operative face of the detector parallel to the path. A reading of the intensity of light from the source sensed by the detector is taken in one position with the element in the light path and in another position with the element absent. The positions being such that the two readings are equal. The angles .THETA. and .alpha. of incidence of light on the detector in the two positions are determined and computer means determine value of ##EQU1## to give the value of the transmission factor.

Growing community of inventors

Rochester, NY, United States of America

James M Cicchiello