Abstract: A microscope includes a holder for holding a sample, an objective for imaging at least apart of a sample held by the holder, a detection module, a control unit for setting the focus position of the objective in a first direction for the recording by means of the detection module, and a focusing module for maintaining a set focus position of the objective. The focusing module includes the control unit, a second detector and first focusing optics with adjustable focal length. The focusing module is switchable into a focus-hold mode, wherein an intensity-modulated object is imaged into the sample via the first focusing optics and the objective, and an image of the imaged object is recorded by means of the second detector. The control unit holds the focus position of the objective on the set focus position, based upon the recording of the second detector.

Abstract: A microscope is provided with a holder for holding a sample carrier, an imaging unit which comprises a first detector and a first imaging optical system for imaging at least one part of a sample held by the sample carrier along a first optical axis onto the first detector, a control unit and a detection unit which comprises an illuminating module, a second detector and a second imaging optical system. The control unit only analyzes the measured values originating from the analysis area by the second detector in order to determine the direction of the change of position of the focus of the first imaging optical system along the first optical axis with the aim of positioning the boundary surface of the sample carrier directed towards the sample side in the depth of field area of the first imaging optical system.

Abstract: A microscope includes a holder for holding a sample, an objective for imaging at least apart of a sample held by the holder, a detection module, a control unit for setting the focus position of the objective in a first direction for the recording by means of the detection module, and a focusing module for maintaining a set focus position of the objective. The focusing module includes the control unit, a second detector and first focusing optics with adjustable focal length. The focusing module is switchable into a focus-hold mode, wherein an intensity-modulated object is imaged into the sample via the first focusing optics and the objective, and an image of the imaged object is recorded by means of the second detector. The control unit holds the focus position of the objective on the set focus position, based upon the recording of the second detector.

Abstract: A method is provided for determining the distance between two optical boundary surfaces spaced apart from each other in a first direction. A first image is ascertained wherein the plane into which the pattern acquired coincides with a first of two optical boundary surfaces or has the smallest distance to the first optical boundary surface in a first direction. A position of the first image in the first direction is determined. A second image is ascertained wherein the plane into which the pattern acquired coincides with a second of two optical boundary surfaces or has the smallest distance to the second optical boundary surface in the first direction. The position of the second image in the first direction is determined. The distance is calculated by means of determined positions of the first and second image.

Abstract: A microscope is provided with a holder for holding a sample carrier, an imaging unit which comprises a first detector and a first imaging optical system for imaging at least one part of a sample held by the sample carrier along a first optical axis onto the first detector, a control unit and a detection unit which comprises an illuminating module, a second detector and a second imaging optical system. The control unit only analyzes the measured values originating from the analysis area by the second detector in order to determine the direction of the change of position of the focus of the first imaging optical system along the first optical axis with the aim of positioning the boundary surface of the sample carrier directed towards the sample side in the depth of field area of the first imaging optical system.

Abstract: A method is provided for determining the distance between two optical boundary surfaces spaced apart from each other in a first direction. A first image is ascertained wherein the plane into which the pattern acquired coincides with a first of two optical boundary surfaces or has the smallest distance to the first optical boundary surface in a first direction. A position of the first image in the first direction is determined. A second image is ascertained wherein the plane into which the pattern acquired coincides with a second of two optical boundary surfaces or has the smallest distance to the second optical boundary surface in the first direction. The position of the second image in the first direction is determined. The distance is calculated by means of determined positions of the first and second image.