OPTICAL ALIGNMENT TOOL AND METHOD OF ALIGNMENT

摘要

An alignment tool for use in calibrating an optical bench and/or alignment of an optical system (e.g. a collector optical system for EUV and X-ray applications), the optical system including multiple nested mirrors (e.g. Wolter I) attached to a mechanical support, the tool comprising a mechanical interface plate, a lower reference ring, an upper reference ring and a pinhole member being disposed spaced apart axially in sequence, a first positioning device (e.g. x,y translation stage), attached to the mechanical interface plate and to the lower reference ring, the first positioning device being adapted for precisely adjusting the position of the lower reference ring in two dimensions, a second positioning device (e.g. x,y translation stage), attached to the mechanical interface plate and to the upper reference ring, the second positioning device being adapted for precisely adjusting the position of the upper reference ring in two dimensions, a third positioning device (e.g. x,y,z translation stage), attached to the upper reference plate and to the pinhole member, the third positioning device being adapted for precisely adjusting the position of the pinhole member in three dimensions, a mechanical interface (e.g. comprising three reference v-grooves), the mechanical interface being mounted on or integral with the mechanical interface plate and being substantially identical in form to that of the mechanical support of the optical system Also disclosed is an apparatus for calibrating an optical bench and/or alignment of an optical system, using the alignment tool, a laser source, and a CCD sensor Also disclosed is a method of calibrating an optical bench, the optical system including multiple mirrors attached to a mechanical support, the method comprising (a) providing the alignment tool, (b) aligning the pinhole member to the axis defined by the mechanical interface, (c) mounting the tool on an optical bench that is to be used to co-align the mirrors of the optical system, (d) positioning a source, for example a laser source, axially and on the side of the pinhole member distant from the mechanical interface plate, (e) aligning the source relatively to the pinhole, (f) positioning a sensor, for example a CCD camera, axially and on the side of the mechanical interface plate distant from the mechanical interface plate, in the area where the focus of the mirrors would be, (g) aligning the sensor along the optical axis relatively to the laser source, (h) aligning the measurement devices, for example micrometers, of the optical bench with respect to the two reference rings, (?) removing the tool from the optical bench Also disclosed is a method of alignment of an optical system, further comprising (I) mounting the mechanical support on the optical bench, (m) positioning a reference mirror on the optical bench, (n) aligning the reference mirror relatively to the laser source and to the reference rings, (o) removing the reference mirror from the optical bench, (p) attaching the mirrors of the optical system to the mechanical support, thereby forming the optical system, and (q) removing the optical system from the optical bench.