Photocopying – Projection printing and copying cameras – Focus or magnification control
Reexamination Certificate
2005-03-15
2005-03-15
Nguyen, Henry Hung (Department: 2851)
Photocopying
Projection printing and copying cameras
Focus or magnification control
C355S053000, C355S067000
Reexamination Certificate
active
06867846
ABSTRACT:
A wavefront measurement system includes a source of electromagnetic radiation. An imaging system directs the electromagnetic radiation at an object plane that it uniformly illuminates. A first grating is positioned in the object plane to condition the radiation entering the input of a projection optic. A projection optical system projects an image of the first grating onto the focal plane. A second grating is positioned at the focal plane that receives a diffracted image of the source to form a shearing interferometer. A CCD detector receives the image of the first grating through the projection optical system and the second grating that forms a fringe pattern if there are aberrations in the projection optical system. Phaseshift readout of fringe pattern can be accomplished by stepping the first grating in a lateral direction and reading each frame with the CCD detector. The first grating includes a plurality of reflecting lines each formed by a plurality of reflecting dots. The first grating has a pitch that is ½ times the magnification of the projection system times the pitch of the second grating for achromatic operation.
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ASML Holding NV
Sterne Kessler Goldstein & Fox P.L.L.C.
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