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Using LEED

Acquiring images

  1. Switch off the light sources in the chamber, i.e. external lamps and ionization gauge filament by pressing EMIS on the gauge controller:

    Exposing the camera to strong light may damage the CCD sensor (sensitivity loss)!
  2. Cover the CF160, CF100 and CF38 viewports towards LEED with the plastic covers.
  3. Connect the electric plug of the camera power supply to the socket.
  4. Start the KolLEED software. On the card Acquire setect Grab:
  5. Observe the LEED pattern on the computer display. With the averaging turned off the framegrabbing is quite fast but with visible noise.
  6. Select the parameters of the images you would like to save. Write down a list containing parameters for each image to be saved, i.e. the corresponding energy, screen voltage and filament current (if changed).
  7. To improve the quality of the saved images turn the averaging on and subtract the background. It is done by turning the screen voltage off and software button sequence Stop - Averaging on - Grab - Clear background - Get background. Then turn the screen voltage on again. From this point on the framegrabbing is much slower but the noise is significantly reduced.
  8. Now set the controller parameters (energy, screen voltage, filament current if changed) to the values in your list.. At each setting you can acquire the image into memory by clicking on the image or on Add To Browser. Provisional filenames in the format <untitled_> will appear in the browser. Write down the corresponding _numbers to every set of parameters in your list.
  9. When finished go to Browser card of the software, select each image and Save it into the correct folder under a filename consulting your list. We suggest writing all parameters into every filename, e.g. 171104_cleanPt_80eV_5kV_1.1A.jpg, means clean platinum measured on 4 Nov 2017 at 80 eV energy, 5 kV screen voltage and 1.1 A filament current.
  10. When you close KolLEED all acquired but unsaved images will be lost (without any confirmation).
  11. Do not forget to disconnect the electric plug of the camera power supply before switching on any light in the chamber (lamps, ionization gauge).

Last Updated on Monday, 11 May 2020 13:35