U.S. Philips Corporation

Guido C Van De Looy

Gijsbertus Bouwhuis

Adrianus Gerardus Bouwer

Antonius H Akkermans

A device is described for detecting a magnification error in an optical imaging system comprising a lens system (L.sub.1, L.sub.2) which is telecentric at one side. Two gratings (RG.sub.1, RG.sub.2) arranged in the object plane (MA) are imaged onto two gratings (WG.sub.1, WG.sub.2) arranged in the image plane (W; WT) and the radiation beams (b.sub.1, b.sub.2) by means of which these images are formed are incident on two radiation-sensitive detection systems (D.sub.1, D.sub.2) which supply periodic signals (S.sub.1, S.sub.2). By phase comparison of these signals a magnification error (S.sub.ME) and, if desired, a focussing error can be measured very accurately.

Device for detecting a magnification error in an optical imaging system

An opto-lithographic device comprising a lens system (13) arranged between a mask support (25) and a substrate table (33) and telecentric on one side, the lens system (13) and the mask support (25) being secured to a first holder (21) and a second holder (23), respectively, which can be displaced both simultaneously and relatively by means of a first actuator (183, 187, 189) and a second actuator (197, 199) for adjustment of focusing and enlargement. The invention provides the possibility of a simple correction of focusing and enlargement when this focusing and this enlargement are varied inter alia due to pressure or temperature variations.

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Eindhoven, Netherlands

Guido C Van De Looy