Abstract: A computer-implemented method includes receiving a focal image stack. The focal image stack includes multiple images of a measurement object. Each of the images captures a region of a surface of the measurement object with a defined focal plane position in a depth direction. The defined focal plane positions of the plurality of images are different from each other. The method includes generating an initial image with an extended depth of field in the depth direction based on the focal image stack. The method includes generating a corrected image by correcting a set of imaging errors in the initial image. The set of imaging errors includes a distortion error.

Abstract: A method for generating a depth map of a region of a surface of a workpiece includes receiving a stack of images. The images image the region of the surface of the workpiece with defined focal plane positions that are different in a depth direction and a focal plane position is assigned to each. Image points of the images are respectively assigned to a corresponding object point on the surface. The method includes determining a focus value of each image point of each image. The method includes fitting a function along the depth direction to the focus values of those image points that are assigned to the same object point. The method includes determining a depth value of each object point on the surface in the depth direction based on an extremum of the fitted function. The method includes generating the depth map based on the determined depth values.

Abstract: A magnifying imaging optical unit is part of a metrology system for examining objects. The magnifying imaging optical unit has at most four mirrors which image an object field in an object plane into an image field in an image plane. According to one aspect, an entrance pupil of the magnifying imaging optical unit has a boundary shape which deviates from an ellipse and the aspect ratio of which is not equal to 1. In accordance with a further aspect, reflection surfaces of small-area mirrors which are used for guiding imaging light along an imaging beam path deviate from a spherical shape by at most 10 ?m. This results in a magnifying imaging optical unit in which an imaging result which satisfies the stringent requirements of a metrology system results for a given manufacturing outlay.

Abstract: A method for generating a depth map of a region of a surface of a workpiece includes receiving a stack of images. The images image the region of the surface of the workpiece with defined focal plane positions that are different in a depth direction and a focal plane position is assigned to each. Image points of the images are respectively assigned to a corresponding object point on the surface. The method includes determining a focus value of each image point of each image. The method includes fitting a function along the depth direction to the focus values of those image points that are assigned to the same object point. The method includes determining a depth value of each object point on the surface in the depth direction based on an extremum of the fitted function. The method includes generating the depth map based on the determined depth values.

Abstract: An illumination optical unit is part of a mask inspection system for use with EUV illumination light. A hollow waveguide serves to guide the illumination light. For the illumination light, the hollow waveguide has an entrance opening in an entrance plane and an exit opening in an exit plane. An input coupling mirror optical unit is disposed upstream of the hollow waveguide in the beam path of the illumination light and has at least one mirror for imaging a source region of an EUV light source into the entrance opening of the hollow waveguide. An output coupling mirror optical unit serves to image the exit opening of the hollow waveguide into an illumination field. This yields an illumination optical unit whose use efficiency for the EUV illumination light has been optimized.

Abstract: A computer-implemented method includes receiving a focal image stack. The focal image stack includes multiple images of a measurement object. Each of the images captures a region of a surface of the measurement object with a defined focal plane position in a depth direction. The defined focal plane positions of the plurality of images are different from each other. The method includes generating an initial image with an extended depth of field in the depth direction based on the focal image stack. The method includes generating a corrected image by correcting a set of imaging errors in the initial image. The set of imaging errors includes a distortion error.

Abstract: A method for generating a depth map of a region of a surface of a workpiece includes receiving a stack of images. The images image the region of the surface of the workpiece with defined focal plane positions that are different in a depth direction and a focal plane position is assigned to each. Image points of the images are respectively assigned to a corresponding object point on the surface. The method includes determining a focus value of each image point of each image. The method includes fitting a function along the depth direction to the focus values of those image points that are assigned to the same object point. The method includes determining a depth value of each object point on the surface in the depth direction based on an extremum of the fitted function. The method includes generating the depth map based on the determined depth values.