Radiant energy – Inspection of solids or liquids by charged particles – Electron probe type
Patent
1979-08-06
1981-09-08
Anderson, Bruce C.
Radiant energy
Inspection of solids or liquids by charged particles
Electron probe type
250397, 250399, G01N 2300
Patent
active
042886929
ABSTRACT:
X-ray spectral data are normalized to beam current by basing data accumulations upon a fixed beam current integral rather than a fixed acquisition time. A current proportional to beam current is obtained from an aperture in an electron column instrument to provide a continuous monitor of beam current during data accumulation. The current is applied to a digital current integrator producing output pulses at a frequency proportional to the current. Connected to the digital current integrator is a one-shot producing a pulse of fixed width for each integrator pulse. The interval between one-shot pulses is defined as "delay time," and a signal representative of that time interval is produced and utilized to control the actual analysis time such that a prescribed beam current integral is obtained. The delay time signal may be combined with the normal system dead time signal to derive an effective dead time signal for controlling the length of actual analysis time to correct for variations in beam current as well as system dead time.
REFERENCES:
patent: 3909612 (1975-09-01), Gibbard
"+AI Acquisition with Integrator", Schamber, 1976.
"Instrumentation", Rucklidge, Mineralogical _Ass. of Canada Short Course in Microbe Tech., Edmonton, Canada, May 1976.
"Artifacts Observed in Energy-Dispersive X-ray Spect. in the SEM", Fiori et al., National Bureau of Standards Publication, 1978.
"Electron Beam Microanalysis", Beaman et al., ASTM Special Tech. Pub. 506.
McCarthy Jon J.
Schamber Frederick H.
Anderson Bruce C.
Tracor Northern, Inc.
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