Beam current normalization in an X-ray microanalysis instrument
US4288692A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 6, 1979 |
| Grant date | Sep 8, 1981 |
| Priority date | — |
| Expiry date | Aug 6, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/28
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.