US 12,259,232 B2
Method and inspection device for optically inspecting a surface
Stefan Leute, Herten (DE); and Koichi Harada, Kanagawa (JP)
Assigned to ISRA VISION GMBH, Darmstadt (DE)
Appl. No. 17/917,812
Filed by ISRA VISION GMBH, Darmstadt (DE)
PCT Filed Mar. 22, 2021, PCT No. PCT/EP2021/057217
§ 371(c)(1), (2) Date Oct. 7, 2022,
PCT Pub. No. WO2021/204521, PCT Pub. Date Oct. 14, 2021.
Claims priority of application No. 10 2020 109 945.2 (DE), filed on Apr. 9, 2020.
Prior Publication US 2023/0140278 A1, May 4, 2023
Int. Cl. G01B 11/25 (2006.01); G01N 21/88 (2006.01)
CPC G01B 11/2513 (2013.01) [G01B 11/2518 (2013.01); G01N 21/8806 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method for optically inspecting a curved surface (10) of an object by means of an inspection device, said method providing the following steps:
generating, by means of an illumination device of the inspection device, a temporally periodic pattern with different illumination patterns is on the surface during an image recording sequence and recording, during the image recording sequence a number of images of the pattern on the surface by means of an image recording device of the inspection device,
wherein the illumination device and the image recording device are arranged in the reflection angle (α) and wherein the object is moved relative to the inspection device during inspection of the surface;
wherein generating one of the different illumination patterns is synchronised, respectively, with the image recording of one of the images of the pattern such that each image from the image recording sequence is recorded, respectively, with a known illumination pattern of the different illumination patterns;
determining the phase of the pattern from the succession of recorded known illumination patterns in at least one image point;
detecting defects on the surface from deviations of the illumination pattern recorded in at least one image from the generated known illumination pattern;
wherein the duration of the image recording sequence is chosen such and the illumination pattern is generated by the illumination device such that the area of the illumination pattern visible in the image points of the images recorded during each image recording sequence can be regarded as constant by selecting the period length of the pattern in the illumination pattern such that, depending on a topology of the surface in direction of the pattern course, an intensity change does not exceed a selected criterion, so that a sequence reflection zone, which is defined as the surface area covered in total by the reflection zones in the respective images from the image recording sequence, can be regarded as constant.