ELECTRON MICROSCOPES AND MICRO-ANALYSERS

• US 3,786,271 A
• Filed: 02/14/1972
• Issued: 01/15/1974
• Est. Priority Date: 02/12/1971
• Status: Expired due to Term

• Current Assignee: David Charles Joy, Graham Roger Booker
• Original Assignee: David Charles Joy, Graham Roger Booker
• Inventors: Joy, David Charles, Booker, Graham Roger
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Anderson, B. C.
• Application Number:
  US05/225,968
• Time in Patent Office: 701 Days
• Field of Search: 250/49.5R,49.5A,49.5PE,398
• US Class Current: 250/398
• CPC Class Codes: H01J 37/256 using scanning beams
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

In a scanning electron beam instrument also capable of being used to exhibit pseudo-Kikuchi (electron channelling) effects by causing the electron beam to rock angularly or spirally about a substantially fixed point on a specimen surface the electron beam is switched rapidly between the rocking (electron channelling) mode and the linear scanning (micrograph) mode to allow the simultaneous display of information derived from both modes.

Claims

1. A scanning electron beam instrument comprising means for forming a beam of electrons and causing said beam to impinge on a suitably placed specimen surface in the path thereof, at least one device for detecting the effect on said specimen surface of the impact thereon of said beam, means for displaying the resulting information, first scanning control means acting on said electron beam and serving to deflect said beam laterally so as to scan linearly a finite region of said specimen surface, second scanning control means acting on said electron beam and serving to deflect said beam angularly about a fixed point on said specimen surface, whereby said beam rocks about said point, and repetitively operating switching means acting on said first and second scanning control means to make each of said control means operative in turn, said switching means acting also on said displaying means whereby information from said detecting device resulting from said linear scanning and said rocking are simultaneously displayed.

2. The instrument set forth in claim 1 including two of said detecting devices and two respective displaying means.

3. The instrument set forth in claim 1 wherein said switching means include means alternately directing information from a single said detecting device to each of two separate said displaying means.

4. The instrument set forth in claim 1 wherein said first and second scanning control means include some elements common to both means.

5. The instrument set forth in claim 4 wherein said first scanning control means comprise a time base generator and associated first and second axially spaced deflecting coils, and said second scanning control means comprise said time base generator and first deflecting coils and a focussing electromagnetic lens acting simultaneously as deflection means.

6. The instrument set forth in claim 5 wherein said switching means comprise firstly means for switching on and off said second deflecting coils and secondly means for altering the power of said first deflecting coils.

7. The instrument set forth in claim 4 wherein said first and second scanning control means comprise deflection means common to both control means, and means for acting on a part of said deflecting means to operate said part at two different levels, one in which said beam rocks about a point on said specimen surface, and a second in which said beam rocks about a point displaced along the axis of said beam from said specimen surface.

8. The instrument set forth in claim 7 wherein said part of said deflecting means comprise an electromagnetic lens serving also as focussing means for said beam.