Patent ID: 7420670

Claim:
A measuring instrument for measuring at least one of the position and width of an object, the measuring instrument comprising: a light source configured to illuminate at least a part of the object; a detector; an illuminating beam path extending from the light source to the object; a detection beam path extending from the object to the detector; at least one of an illuminating optics disposed in the illuminating beam path and an imaging optics disposed in the detection beam path, the imaging optics being configured to image the at least a part of the object onto the detector; a position evaluation device configured to determine a distance between two points of the object; and an optical device configured to impose a profile of a continuously monotonic function on an intensity of light from the light source and configured to reduce outwardly the light intensity of the illuminating or detection beam path with respect to a respective optical axis of the illuminating or detection beam path, the optical device being disposed in at least one of a pupil plane of the imaging optics, a pupil plane of the illuminating optics, and a plane in the illuminating or imaging beam path conjugate with the pupil plane of the imaging optics or the pupil plane of the illuminating optics.