Radiant energy – With charged particle beam deflection or focussing – With detector
Patent
1983-03-01
1985-04-30
Smith, Alfred E.
Radiant energy
With charged particle beam deflection or focussing
With detector
250396R, 250310, 250311, 315382, G21K 108, H01J 314, H01J 2958
Patent
active
045146349
ABSTRACT:
An automatic focussing arrangement for use with scanning electron beam apparatus such as a scanning electron microscope or electron beam microfabrication apparatus sets the focus coil (18) current at each one of a plurality of predetermined values in turn. At each setting, the scanning system (10, 12, 14) is activated to frame-scan the electron beam across a predetermined sharp-edged target. The resultant video signal (22) is monitored for each line of the frame scan to derive the mean value, then the mean value is subtracted from the instantaneous value of the video signal for that line (this may be carried out during a second scan of the same line), and the difference is then squared and integrated. The integrated outputs corresponding to each line scan are monitored to determine the greatest one. This is then stored (32) in association with the corresponding level of the focus drive current, and the process is then repeated. When frame scans have been carried out corresponding to all values of the focus current, the maximum one of all the stored integrated outputs is determined by a computer (38) and this identifies the optimum focus drive current. The focus drive current may then automatically be set to this value via a presettable counter (36).
REFERENCES:
patent: 3937959 (1976-02-01), Namae
Berman Jack I.
Cambridge Instruments Limited
Smith Alfred E.
LandOfFree
Electron beam focussing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electron beam focussing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electron beam focussing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1970015