Beam into the chamber

The first step is to get beam into the microscope chamber. Go to some relatively large beamline slit settings (like 200/200/0 slits, for ENS_I=200 $\mu$m, EXS_I=200 $\mu$m, and EXSY_I wide open). Look in the upstream inboard viewport; you should see the snout as a long metal tube with a glass section in its middle (see Fig. A.2). Inside this glass section is a mirror that lets you look down the direction of the beam path towards the exit window between the beamline vacuum and the inside of the STXM IV chamber. You should be able to see beam on the phosphor around the exit window, and adjust the chamber accordingly.

If the microscope is close to being aligned, you can simply monitor the flux on a detector to evaluate the alignment of the microscope chamber to the beam. If you are really starting from the beginning, you will need to remove the zone plate and OSA (see Sec. 2.4), and scan a 5-10 $\mu$m diameter pinhole as the sample to evaluate the illumination of the exit window.

Figure A.2: Picture of the STXM IV snout. The kinematic mount platforms for the zone plate and OSA are shown as mZP and mOSA, respectively. The glass cones on which they are mounted are shown as cZP and cOSA. The mirror on which you look to see the x-ray beam on the phosphor around the exit window is indicated with Mirror.

Start with the ZP and OSA removed. From the File$\rightarrow$Edit Alignment menu in SM, select Insert laser. This will move the detector platform so that beam should pass between detector D1 and the VLM, and strike a phosphor plate located in front of an alignment laser. (You may have to move the detector platform around a bit to make sure x-rays are hitting on the phosphor alongside but not directly at the $\sim 1$ mm laser aperture). Now select Insert photodiode from the Edit Alignment menu, so that beam strikes the IRD silicon photodiode. You should get a signal comparable to what is shown in Table A.3. Update values of photodiode_xdet_um and photodiode_ydet_um in the alignment file; see Sec. B.1.