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US 8,571,826 B2Granted
Correction of imaging errors in alignment system with several measurement planes located in succession in the beam path
AssigneePruftechnik Dieter Busch AG
InventorHeinrich Lysen
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Abstract
A method for correction of the measured values of optical alignment systems with at least two measurement planes which are located in succession in the beam path. From each measurement plane, the beam path to the light source is transformed back in order to compute new incidence points using a beam which has been corrected by taking into consideration imaging errors.
Claims9
Method for the alignment of objects with respect to each other, comprising the steps of:
- directing a light beam of low divergence from a light source arranged on a first object, through an optical system of an alignment device with at least two detectors which are arranged on a second object, the detectors being located in succession in the beam path for determining the incidence points of the light beam on measurement planes of the detectors,
- mathematically transforming the point of incidence of the beam on each measurement plane according to optical rules backwards through the optical system to the light source,
- with the transformation, determining a measurement beam with corrected incidence points on the individual measurement planes, and
- using the corrected incident points for determination of the existence of any misalignment of the objects with respect to each other;
- and
- correcting the alignment of the objects based on any misalignment of the objects determined to exist.
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Dependencies are inferred from the claim text.