Patent ID: 7212294

Claim:
A method for determination of the level of at least two measurement points with respect to each other, comprising the steps of: producing a light beam having a cross-sectional intensity distribution with a preferred direction and directing the light beam in a first direction, deflecting the light beam through 90° with respect to the first direction to a second direction, with the second direction being rotated through a rotation angle corresponding to a position of the measurement point about an axis formed by the first direction, receiving the light beam deflected to the second direction on a detector surface which is positioned successively at each measurement point by movement of the detector surface and without changing the position at which the light beam is deflected, determining the incidence level of the light beam and the orientation of the preferred direction of the cross-sectional intensity distribution of the light beam on the detector surface for each measurement point, determining the rotation angle for each measurement point from the respective orientation of the preferred direction on the detector surface; and determining the level of the measurement points with respect to each other based upon the incidence level and rotational angle determined for each measurement point on the detector surface itself.