Abstract: The invention relates to alignment marks for a process for aligning two objects relative to each other by means of an image recognition system wherein the lines are optoelectronically scanned and the obtained brightness values are integrated line-by-line. The advantages of the alignment marks according to the invention reside in that position inaccuracies due to the mutual optical influence of the alignment marks in the optoelectronic evaluation are avoided and furthermore in a high evaluation speed.

Abstract: In the described optical device a linear object element forms an image by two straight lines crossing each other at a specific angle. Thus it is possible to achieve a crosswise movement of the image point downstream of the optical device with only a single linear scanning movement upstream of the optical device. In particular it is possible to scan plane structures with a single scanning movement.

Abstract: For the automatic focussing of an optical instrument on an object, a measng diaphragm is inserted into the illuminating radiation path, which diaphragm is to be projected onto the object plane and focus plane during focussing. This intermediate image of the measuring diaphragm is projected via a detector diaphragm which is complementary to the measuring diaphragm, onto a detector, the output signal of which is a scale for the quality of the focussing and which acts on a focussing drive in the sense of optimum focussing via a control device.

Abstract: A parallelizing gauge in a wedge error correction head for the parallel adjustment of a substrate plate to the plane of a light exposing mask, with a means being provided for introducing and removing substrate plates and masks into and/or out of the intermediate space between the light source and the substrate support. At least three foil segments are provided, each being distributed over the circumference of the wedge error correction head and extending radially inwardly, and each being controllably movable in a radial direction.

Abstract: The invention concerns a process for the two-sided exposure of a semiconductor or substrate plate, especially exposure of a wafer, through exposure masks which are arranged in plane parallel, parallel and rotational alignment to either side of a semiconductor plate. The invention further concerns an apparatus for parallel and rotational alignment to either side of a semiconductor plate. The invention further concerns an apparatus for parallel and rotational alignment of a semiconductor or substrate plate, especially alignment of a wafer, in relation to two exposure masks, operating on either of the two surfaces of the semiconductor or substrate plate, for the purpose of a two-sided exposure, in accord with the process established by the invention.