| 摘要 |
A scanning particle beam instrument is provided, the instrument including a scanner (40, fig.3), a radiation detector 18 and a DC amplifier 36, the DC amplifier 36 being operable to amplify a signal generated by the radiation detector diode 34 to produce a video signal, the instrument further including a controller operable to so direct the beam 14 relative to a specimen 16, or to determine when the beam 14 is so directed relative to a specimen 16, that an actual video signal produced by the DC amplifier 36 may be compared with a desired video signal (44, fig.3), to compare actual and desired video signals and to adjust a DC offset of the DC amplifier 36 so as to reduce a difference between the signals. Also provided is a method of producing a video signal using such an instrument. |
