Patent ID: 11953431
Assignee: AXALTA COATING SYSTEMS IP CO., LLC
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 17:
18. A method of measuring color of a target coating comprising:
illuminating the target coating with a beam of electromagnetic radiation at an entrance angle, where a spherical coordinate system is used, where a surface of the target coating is a reference plane of the spherical coordinate system, an origin of the spherical coordinate system is about a point where the beam impacts the surface of the target coating, a zenith of the spherical coordinate system is a line normal to the surface of the target coating, wherein the entrance angle is a polar angle measured from the zenith, wherein the beam is defined with an azimuth angle of 0, wherein the target coating comprises flakes, wherein a target population of flakes is defined by all the flakes in the target population of flakes having the same angled flake normal polar angle, and wherein the beam illuminates the target population of flakes;
measuring an intensity of the electromagnetic radiation with a first detector positioned at a first polar angle measured from the zenith, wherein the first detector is positioned to receive electromagnetic radiation reflected from the beam by the target population of flakes;
measuring the intensity of the electromagnetic radiation with a second detector positioned at a second polar angle measured from the zenith, wherein the entrance angle for the source is the same for the position of the first detector and for the position of the second detector, wherein the second polar angle is different than the first polar angle, and wherein the second detector is positioned to receive electromagnetic radiation reflected from the beam by the target population of flakes; and
wherein a specular line extends from the surface of the target coating at a specular angle, wherein the specular angle is the polar angle equal to the entrance angle, wherein the specular line has the azimuth angle of 180°, wherein a positive aspecular exit angle is defined between the specular line and a first exit line, wherein the first exit line extends from the first detector to the origin, and wherein a negative aspecular exit angle is defined between the specular line and a second exit line extending from the origin to the second detector, and wherein;
the negative aspecular exit angle is greater than the positive aspecular exit angle.