| 摘要 |
A device for influencing an electron beam, for example a beam deflecting device in an electron beam lithography machine, comprises a beam influencing coil ( 13 ) operable to influence an electron beam (EB) in the vicinity of the device by way of a magnetic field and a heat dissipation compensating coil ( 14 ) operable to provide a heat output so compensating for any change in heat dissipation of the device due to operation of the beam influencing coil ( 13 )-particularly variable operation to vary the field intensity or to create and remove a field-as to reduce the amount of change, preferably to maintain the net heat dissipation at a constant value. The compensating coil ( 13 ) can be controlled, for example, by measurement ( 19 ) of the heat dissipation of the device and calculating ( 18 ) current supply ( 16 ) to the coil ( 13 ) in dependence on the measured dissipation.
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