Dave Mitchell's DigitalMicrograph™ Scripting Website

Function

Enables screen current density (read off the fluorescent screen) to be converted into a true current.

Version

version:20140322, v1.0

Author

D. R. G. Mitchell

Acknowledgements

Thanks to Gilberto Casillas-Garcia for assistance with current measurements.

Comments

Currents measured using the large or small pop-up fluoescent screens are usually reported as current densities (requiring the area of the screen to be known in order to convert to current). They also read low due to backscattering and secondary electron generation (by about 1.2x at 200kV and about 1.55x at 80kV). If the relationship between screen current densities and accurate beam currents (measured with a drift tube) are stored in this script, it can be used to convert fluorescent screen current densities to reasonably accurate beam currents on the fly - in both TEM and STEM mode.

System Requirements

Should be compatible with all recent versions of DigitalMicrograph.

Known Issues

Data reported here were obtained on a JEOL ARM 200F at 200 and 80kV. You need a way of measuring the actual current accurately - this is difficult without a GIF/Drift Tube or Faraday Cup/Holder of some kind.

Supported

Yes

Included Files

Main script file.

Source Code