US 11,988,558 B2
Method and device for identifying interference pigments in a coating
Markus Mundus, Münster (DE); Guido Bischoff, Münster (DE); Thomas Kantimm, Münster (DE); and Martin Schmitz, Münster (DE)
Assigned to BASF COATINGS GMBH, Muenster (DE)
Appl. No. 17/432,609
Filed by BASF COATINGS GMBH, Münster (DE)
PCT Filed Feb. 19, 2020, PCT No. PCT/EP2020/054381
§ 371(c)(1), (2) Date Aug. 20, 2021,
PCT Pub. No. WO2020/169678, PCT Pub. Date Aug. 27, 2020.
Claims priority of application No. 19158943 (EP), filed on Feb. 22, 2019.
Prior Publication US 2022/0120614 A1, Apr. 21, 2022
Int. Cl. G01N 21/55 (2014.01); G01J 3/46 (2006.01); G01J 3/50 (2006.01); G01N 21/25 (2006.01); G06T 7/90 (2017.01)
CPC G01J 3/504 (2013.01) [G01J 3/463 (2013.01); G01N 21/251 (2013.01); G01N 21/55 (2013.01); G06T 7/90 (2017.01); G06T 2207/10024 (2013.01); G06T 2207/10152 (2013.01); G06T 2207/30156 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method for identifying an interference pigment (103) in a coating (101), comprising at least the following steps:
illuminating the coating (101) applied to a surface with light at a first illumination angle (θinc1) relative to the normal to the surface,
recording a first image of the coating (101) applied to the surface with light at a first aspecular measuring angle (θas1), measured in relation to the Bragg angle (θspec), assigned to the first illumination angle (θinc1);,
illuminating the coating (101) applied to the surface at at least one second illumination angle (θinc2) different from the first, relative to the normal to the surface,
recording at least one second image of the coating (101) applied to the surface at the first aspecular measurement angle, measured in relation to the Bragg angle (θspec2), assigned to the at least one second illumination angle (θinc2), or a corrected first aspecular measurement angle (θas2), measured in relation to the Bragg angle (θspec2), assigned to the at least one second illumination angle (θinc2) wherein the corrected first aspecular measurement angle (θas2) is obtained from the first aspecular measurement angle (θas1) by correction in accordance with an optical refraction of the light that has changed at the at least one second illumination angle (θinc2)as compared with the first illumination angle (θinc1),
spatially analyzing and evaluating the first image and the at least one second image,
spectrally analyzing and evaluating the first image and the at least one second image, and
identifying the interference pigment (103) on the basis of the spatial and spectral analysis and evaluation of the first image and the at least one second image, the first and the at least one second illumination angle (θinc1, θinc2) and the first aspecular measurement angle (θas1) or the corrected first aspecular measurement angle (θas2);
wherein the aspecular angle is calculated according to the following formula:
θas=arcsin[ncoating/nsurroundings*sin(arcsin(nsurroundings/ncoating*sin(θinc))+α)]−θinc.