Patent ID: 9671601
Date: 2017-06-06
CPC Classifications: G02B,G03B,G03F

Claim:
1. A method for autofocusing in a context of microscopic examination of a specimen, the method comprising: providing the specimen located at a focus of a microscope objective of a microscope; providing a deflection device arranged on an opposite side of the microscope objective relative to the specimen; providing an autofocus beam path directed toward the microscope objective, and from the microscope objective to a reflective autofocus interface in a specimen region, reflecting the autofocus beam path at the autofocus interface and directing the reflected autofocus beam path via the microscope objective and via the deflection device toward an autofocus detector; generating interfering sub-beams of the autofocus beam path by splitting of the autofocus beam path at two reflecting regions of the deflection device, wherein the sub-beams are spaced apart in a propagation direction of the autofocus beam path, each of the two reflecting regions reflecting a sub-beam of the autofocus beam, whereby two sub-beams both travel through the microscope objective, meet at the focus of the objective and are reflected at the reflective autofocus interface; arranging the autofocus detector in a plane conjugated with the microscope objective pupil in order to acquire an interference pattern that is generated; and adjusting the focus of the microscope by using a Fourier transform to (1) evaluate the acquired interference pattern with respect to a phase angle of the interference pattern (2) determine locations of maxima in a planar coordinate system of the Fourier transform of the interference pattern, and (3) evaluate relative locations of the maxima with respect to one another and/or with respect to a location of one of the maxima in the coordinate system of the Fourier transform.