| 摘要 |
<p>A device for positioning a body (5) by means of at least two electromagnets (13, 15). A position sensor (29) measures the size of an air gap (23) between one of the electromagnets (13, 15) and a guide beam (1). An output signal of the position sensor (29) is offered to an electronic control unit (35) which passes a control current through the electromagnets (13, 15) in dependence on a difference between the measured and a desired size of the air gap (23). An electronic multiplier (47, 59) is connected between the control unit (35) and each of the electromagnets (13, 15), multiplying a control signal from the control unit (35) by the output signal from the position sensor (29). In this way it is achieved that a force exerted by the electromagnets (13, 15) on the guide beam (1) depends exclusively on the value of the control signal and not on the size of the air gap (23), so that a position-independent control is obtained. Such an accurate position-independent control may be used in an optical lithographic device for the irradiation of semiconductor substrates. Alternatively, such an electromagnetic support with a position-independent control may be constructed so as to form a micromanipulator. <IMAGE></p> |
