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Abstract

An optical lithographic device having a machine frame (1) to which is fastened a lens system (11) having a vertical optical main axis (13). Below the lens system (11), a positioning device (35) is fastened on a support member (3) of the machine frame (1), by means of which device an object table (27) is displaceable relative to the lens system (11) over a guide surface (5) of the support member (3) extending perpendicular to the optical main axis (13). The device is provided with a force actuator system (67) fastened to a reference frame (83) and controlled by a feedforward control system (95). The force actuator system (67) exerts a compensatory force on the support member (3) with a direction opposite to a direction of a reaction force simultaneously exerted by the positioning device (35) on the support member (3), and with a value which is substantially equal to a value of the said reaction force. The control system (95) further comprises a negative acceleration feedback (107), whereby the force actuator system (67) exerts a control force on the support member (3) which is determined by an acceleration of the support member (3) measured by an acceleration transducer (111, 113, 115). The use of the force actuator system (67) prevents undesirable movements of the support member (3) under the influence of a reaction force exerted by the positioning device (35) on the support member (3) and under the influence of external forces. The optical lithographic device can be used inter alia for illuminating semiconductor substrates, where a semiconductor pattern provided on a mask (17) is imaged on a semiconductor substrate (25), which is positioned on the object table (27), by means of the lens system (11).

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First Claim