Visible light microscope (VLM) setup

For details on how to operate the VLM and display the image on the computer screen, refer to Sec. 2.3. In short:

• Insert the sample stage without a sample in place. Bring the snout into the operating position (micrometer reading 15.00 mm for inboard STXM, 27.0 mm for outboard STXM). Move the VLM by moving XDET, YDET and ZDET to be in focus on the exit window of the snout, with the snout approximately centered on the window (see Fig. 12.1). To do this you might need to move the sample stage a little bit further upstream (so as to be able to move far enough upstream with the VLM).
• Mark the position of the exit window on the computer screen with a permanent marker (can be removed with ethanol). Remember to align the field of view to the lower right corner of the Desktop before doing this.
• Record the detector stage position for $X$ and $Y$. This gives you the reference VLM position for it being on the beam axis. Enter them into the alignment file /mnt/x1a/alignment_stxm[i,o].dat. They are the parameters vlm_[x,y]det_um. This establishes the $X$ and $Y$ position of the VLM, for which it is on the beam axis.
• You may also preliminarily set up a detector stage position for $Z$. For this move the VLM a few mm downstream of where the exit snout is in focus (this is the position, where the zone plate would about in focus) read the ZDET position and enter it into the alignment file as vlm_zp_zdet_um.

Figure 12.1: The exit window as viewed by the VLM.