| 摘要 |
A SCANNING ELECTRON MICROSCOPE HAS MEANS (1, 3) FOR GENERATING A BEAM OF ELECTRONS WHICH IS SCANNED OVER A SPECIMEN (11) HELD WITHIN A HOLDER (12) IN A CHAMBER (5) WHICH CONTAINS A GASEOUS MEDIUM. A NEGATIVE POTENTIAL IS APPLIED TO THE HOLDER (12) SO AS TO GENERATE AN ELECTRIC FIELD WHICH ACCELERATES SECONDARY ELECTRONS, FORMED BY THE INTERACTION OF THE PRIMARY BEAM WITH THE SPECIMEN (11), IN DIRECTION AWAY FROM THE SPECIMEN SURFACE AND INTO A COLLISION ZONE (21) IN THE CHAMBER. IN THAT ZONE, THE ACCELERATED SECONDARY ELECTRONS COLLIDE WITH GAS MOLECULES OF THE GASEOUS MEDIUM, THEREBY INITIATING A CASCADE OF COLLISIONS WHICH, IN EFFECT, AMPLIFIES THE SECONDARY ELECTRON SIGNAL. THAT SIGNAL (WHICH MAY TAKE THE FORM OF PHOTONS GENERATED AS A RESULT OF THE COLLISIONS) IS DETECTED BY DETECTING MEANS (10, 7, SUCH AS A PHOTO-MULTIPLIER). (FIGURE 1)
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