Patent ID: 8072607

Claim:
Measuring device for measuring optical properties of a transparent substrate, comprising: a light transmitter arranged relative to a surface of the substrate facing the light transmitter with a defined angle of incidence between an optical axis of the light transmitter and a surface normal of the substrate and emitting diffuse light for illuminating the substrate; and at least one light receiver arranged in an optical path of light emitted from the light transmitter and passing through the substrate with an emergent angle between an optical axis of the light receiver and the surface normal of the substrate; wherein: a) the light transmitter comprises a hollow cylinder with a highly reflective, diffusely dispersive cylindrical inner surface, a first light source arranged in an interior of the hollow cylinder, and a light exit opening arranged in a first base of the hollow cylinder at a distance from the light source, and the light source is arranged at such a distance from the light exit opening and with such direction of propagation of light that light emitted from the light source and multiply reflected in the hollow cylinder emerges as diffuse light from the light exit opening; and/or b) the light receiver comprises a hollow cylinder with a highly reflective, diffusely dispersive cylindrical inner surface, a light sensor arranged in an interior of the hollow cylinder, and a light entrance opening arranged in a first base of the hollow cylinder at a distance from the light sensor, and the light sensor is arranged at such a distance from the light entrance opening and with such a direction of incidence of the light that light entering the light entrance opening and multiply reflected in the hollow cylinder emerges on the light sensor as diffuse light; and wherein the angle of incidence is not equal to the emergent angle.