7. Digital Imaging

Digital imaging allows you to collect X-ray and image data in a digital format for printing and image analysis. These images are acquired by either scanning the beam across the sample or moving the sample under the beam in a discrete grid. The signals collected at each point in the grid (X-rays (WDS or EDS), secondary electrons or backscattered electrons) are plotted, with pixel brightness related to signal intensity (i.e. higher intensities are plotted with brighter colours)

  1. Start the mapping program (Analysis Map Analysis)
  2. Select the proper group and sample.
  3. Select the signals you want to acquire ( Measurement Element Condition)
    1. WDS
      1. Click on the element button and select the elements you want to map using WDS
      2. Click on the condition button and set up the conditions for the elements of interest. If you are trying to image minor elements you should find the correct peak position by using the peak search routine (Monitor Peak Search) on an appropriate standard. The settings for measurement time and background conditions are not used.
    2. EDS
      1. Set up the EDS elements the same way as the WDS elements.
    3. IMS
      1. Select the image signal you want to connect. N.B. only one signal can be collected at a time. If you select SEI and COMP, the image will take twice as long to acquire.
  4. If you are acquiring an SEI or a BEI image, adjust the brightness, contrast, focus and magnification of the image.
  5. Set up the EOS conditions (Measurement EOS condition) Set the desired current using the Probe Current knob. Click on the Read button. Wait until the current is read, and check that the probe scan is off and probe diameter is set to what you want (Almost always zero).
  6. Set up the EDS conditions. If you are not mapping by EDS skip this step.
    1. Open the condition window (Measurement EDS Condition). The easiest way to set up the EDS condition is start the EDS and click the read button. Don't shut down the EDS window, it has to be running during the map acquisition.
    2. Open the EDS analyzer window (EDS Analyser) and set the Count Mode to High. Close the analyser window.
  7. Set up the stage condition. (Measurement Stage condition)

  1. Click the position input button to open the stage window.
  2. Move to the area you want to map, and position the crosshairs roughly in the middle of the area. Click the Read button and then the Store button. Select To Centre.
  3. Next you must decide if you will acquire the image by scanning the sample with the beam or by moving the sample under the beam. Scanning the beam is only recommended in special circumstances.
    1. If you are not collecting X-ray data.
    2. If you are mapping an area less than 100 microns a side.
  4. Click the Beam or Stage(Uni) button. Don't use the Stage(Bi) button.
  5. Beam Scanning
    1. Select 1024 x 1024 pixels.
    2. Make sure that the magnification is the same as the image on the CRT
    3. Click apply, and Close
  6. Stage Scanning
    1. Select appropriate values for number of pixels, pixel size and dwell time. There are no set values for these parameters. Be aware that doubling the number of pixels quadruples the acquisition time. Dwell time should be at least 50 ms if you are interested in minor elements. Dwell times can be as low as 5 ms if you are only mapping for major elements. Since the beam is at least 1 um and probably closer to 2 um, pixel sizes of less than 1 um are not useful
    2. Use the Confirm button to check the mapped area. Click confirm. The stage will move to each corner of the map area. If the area is not correct, you can adjust the size by varying the pixel size and number of pixels. Click the Read button and then the Store button. Select To Centre and check again with Confirm.
    3. When the area is correct click Confirm again and adjust the focus at each corner.
    4. Click apply, and Close.
  7. Close the stage condition window and start the acquisition. (Measurement Preset Measurement)
  1. You can observe the acquisition in real time. Open the Map Analysis program (Process Map Analysis) and click the Realtime button. Select 4 or 9 under Max Maps and then click Start.