Process and device for determining the alignment of two rotatable machine parts, the alignment of two hollow cylindrical machine parts or for testing a component for straightness along a lengthwise side

A process and a corresponding device for determining the alignment of two rotatable machine parts, the alignment of two hollow cylindrical machine parts or for testing a component for straightness along one lengthwise side, with a first measurement unit with a light source for emitting a light beam which has been expanded in one plane, and a second measurement unit with an optical detector unit which has two linear sensors which are arranged parallel to one another, and with an evaluation unit to evaluate a light pattern which has been produced by the two-dimensionally expanded light beam for determining the misalignment of the axes of the machine parts relative to one another, or optionally, the straightness of the component, by the determination the points of incidence of the two-dimensionally expanded light beam on the sensors.