Abstract: A method is useable for determining a thickness of a cover slip or object carrier in a microscope, which has an objective facing toward a sample chamber. Two optical media border two opposing surfaces of the cover slip or object carrier and form two partially reflective interfaces, which are arranged at different distances from the objective. The method includes: deflecting a measurement light beam by the objective with oblique incidence on the cover slip or object carrier; generating two reflection light beams spatially separated from one another by the measurement light beam being partially reflected on each of the two interfaces; receiving the two reflection light beams by the objective and conducting them onto a position-sensitive detector; registering the incidence locations on the position-sensitive detector; and determining the thickness of the cover slip or object carrier based on the registered incidence locations.

Abstract: The present disclosure discloses methods and systems for detecting an IR security mark in a document based on known color information and halftone frequency information. The method includes receiving a document from a user, including an IR security mark. Then, location information, color information and halftone frequency information are received from the user. The document is scanned. Based on the color information and the location information, the IR security mark is extracted from the scanned document. After this, halftone frequency information of the extracted IR security mark is verified. Based on the verification, text in the extracted IR security mark is identified and is then compared with one or more pre-stored IR security marks to ascertain whether the IR security mark in the document is an authentic security mark.