The invention relates to an adjustable pinhole, especially for the illumination beam path and/or detection beam path of a laser scanning microscope. Said pinhole consists of at least two planar basic components comprising articulation points in the form of connecting elements, to which at least one cutting edge that can be displaced in one direction is applied. The basic components advantageously contain at least one integrated preferably optical or electromagnetic positioning element, and a device for preferably optical or electromagnetic position detection is provided on the blade or is connected to the same. The inventive pinhole is advantageously provided with two asymmetric openings oriented in opposite directions for the optical position detection and at least one light source radiates through said openings. A gap which is oriented preferably perpendicularly in relation to the direction of displacement is provided upstream or downstream of the openings and the quantity of light radiated through the gap is detected separately for each opening.