Scan time calculators XFM

Owned by Microscopy Cluster (Unlicensed)
Last updated: Dec 19, 2023 by AS Microscopy Wiki
3 min read

 

The scan time calculators for 2D mapping and XANES imaging will help you determine an appropriate amount of beam time to request when writing an XFM experiment proposal.

The calculators are Excel spreadsheets similar to the XFM scan control spreadsheet. We give a brief description how to use the spreadsheets, and they can be downloaded below.

Please note, currently we scan rectangular areas only.

2D mapping time calculator

You will need to enter into the spreadsheet:

  • Horizontal width in mm

  • Vertical width in mm

  • Pixel size (resolution) in mm. Thus 2 microns is entered as 0.002

  • Pixel dwell time in milliseconds (ms). Typical dwell times are usually between 0.8 and 30 ms, but of course there are exceptions.

The calculator will show the calculated individual scan time in minutes and hours. The Total scan time sums up the individual scans (highlighted in yellow).

Pixel sizes and dwell times have been pre-filled in the spreadsheet. Feel free to change them!

Example 2D mapping scan

Below is a screenshot of the 2D scan time calculator. A 3mm wide by 2mm high scan at 2 micron pixel size with 5 ms dwell time takes approximately 126 minutes or 2.1 hours.

Notice there is a Line overhead and Calculated velocity. Do not edit these fields. The line overhead is the ‘turnaround time’ at the end of a raster scan line. This overhead time can vary depending on scan conditions, but 45 ms is reasonable. The calculated velocity is for your information. When you come to the beamline, we actually enter the scan velocity in our control script rather than the dwell time, so the scan velocity is useful to have.

Download the 2D scan time calculator here:

 

2D XANES imaging calculator

2D XANES imaging is a time consuming technique. Besides the image size and pixel dwell time, the number of XANES energies selected will impact the scan time.

You will need to enter into the spreadsheet:

  • Horizontal width in mm

  • Vertical width in mm

  • Pixel size (resolution) in mm. Thus 2 microns is entered as 0.002

  • Pixel dwell time in milliseconds (ms). Typical dwell times are usually between 0.8 and 30 ms, but of course there are exceptions.

  • Number of Energy steps. This can vary from about 60 to 120, but some users select over 200. Around 100 energy steps seems to be the average.

The calculator will show the calculated individual scan time in minutes and hours. The Total scan time sums up the individual scans (highlighted in yellow).

Pixel sizes and dwell times have been pre-filled in the spreadsheet. Feel free to change them!

Example 2D XANES imaging scan

Below is a screenshot of the 2D XANES imaging scan time calculator. A 1mm wide by 0.2mm high scan at 2 micron pixel size with 2 ms dwell time and 100 energy steps takes approximately 211 minutes or 3.5 hours.

Notice there is a Line overhead and Calculated velocity. Do not edit these fields. The line overhead is the ‘turnaround time’ at the end of a raster scan line. This overhead time can vary depending on scan conditions, but 45 ms is reasonable. The calculated velocity is for your information. When you come to the beamline, we actually enter the scan velocity in the control script rather than the dwell time, so the scan velocity is useful to have.

There is also another factor that is important to keep in mind. Between each scan, it takes about 21 seconds to start the next energy scan. This scan time overhead is included in the calculation.

Download the 2D XANES imaging scan time calculator here:

 

 

Â