| 摘要 |
A scanning particle beam instrument is provided, the instrument including a scanner, a radiation detector and a DC amplifier, the DC amplifier being operable to amplify a signal generated by the radiation detector to produce a video signal, the instrument further including a controller operable to so direct the beam relative to a specimen, or to determine when the beam is so directed relative to a specimen, that an actual video signal produced by the DC amplifier may be compared with a desired video signal, to compare actual and desired video signals and to adjust a DC offset of the DC amplifier so as to reduce a difference between the signals. Also provided is a method of producing a video signal using such an instrument.
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