Patent ID: 9400436
Filing Date: 2016-07-26
CPC Classification: G01B,G03F

Claim Text:
1. A detection device that detects a mark provided on the back side of an object, the detection device comprising: a first detection unit configured to detect the mark from a front side of the object by using a first light that transmits through the object and is reflected by the mark; a second detection unit configured to detect a surface position of the object by using a second light that is reflected by a part of the front side of the object, the part being a mark-free area of the front side of the object; and a processing unit, wherein the processing unit is configured to acquire a first focus position based on an image of the mark detected by the first detection unit and to acquire a second focus position based on the surface position detected by the second detection unit and to determine a thickness of the object based on a difference between the first focus position and the second focus position.