Method and device for measuring optical characteristic variables of transparent, scattering measurement objects
AssigneeVon Ardenne Anlagentechnik GmbH
InventorsHolger Proehl, Thomas Knoth, Tina Schoessler, Martin Dimer
Life of this patent
Estimating the term…
Abstract
A method and device are provided for measurement of various transmission and reflection values of transparent measurement objects having transparent layers in an inline coating system, and particularly the turbidity of the measurement object during a relative movement between the measurement object and measuring device. Transmission fractions are measured in two different radiation directions of a lighting source emitting diffuse light by two photodetectors, by which a fraction of diffuse light of the lighting source is suppressed in one direction.
Claims15
A method for measuring optical parameters of transparent, scattering measurement objects, comprising the following method steps:
- illuminating a transparent, scattering measurement object with diffuse light by an illumination source having a light exit opening, wherein a component of the diffuse light in a radiation direction directed from the light exit opening onto the measurement object is suppressed,
- wherein a integrating sphere having a highly reflective and diffusely scattering inner surface is used as the illumination source, having a light source arranged in an interior of the integrating sphere and a light exit opening apart from said light source, such that no light from the light source passes directly through the light exit opening, and wherein said light proportion in one radiation direction is suppressed by an active light trap arranged in the inner surface of the integrating sphere,
- detecting light from the illumination source that has passed through the measurement object by two photodetectors directed toward the light exit opening from directions deviating from one another, wherein the photodetectors detect simultaneously, said light trap having a position and direction such that in the direction of one of the two photodectors no light component emerges from the light exit opening,
- determining diffuse transmission Tdiffuse of the measurement object from a ratio of light intensity of the light scattered in the measurement object and detected by the first photodetector and the known light intensity of the light incident on the measurement object, and
- determining the total transmission Ttotal of the measurement object from a ratio of light intensity of light that has passed through the measurement object and been detected by a second photodetector of a total transmission channel, of the photodetectors and the known light intensity of the light incident from the measurement object.
A device for measuring optical parameters of transparent, scattering measurement objects, comprising the following components:
- an illumination source having a light exit opening for illuminating a measurement object with diffuse light,
- two photodetectors, which lie in the direction of exiting diffuse light from the light exit at a distance from the light exit opening of the illumination source, wherein each detector input is directed at the light exit opening from direction deviating from one another, wherein the photodetectors detect simultaneously,
- wherein the illumination source is formed by a integrating sphere having a highly reflective and diffusely scattering, inner surface, a light source arranged in an interior of the integrating sphere and the light exit opening spaced apart from said light source, such that no light from the light source passes directly through the light exit opening,
- where an inner surface of the integrating sphere has an active light trap in a position and direction such that in the direction of one of the two photodetecters no light component emerges from the light exit opening,
- a sample accommodating space arranged between the light exit opening of the illumination source and the photodetectors in such a way that light emerging from the illumination source firstly passes through a measurement object arranged within the sample accommodating space and then enters the photodetectors.
Dependencies are inferred from the claim text.