Align KB2 with WFS Grating

The goal is to get the optimal wavefront for nano focusing. 

  1. Install a burn paper at IP
    1. Look at the paper with a inline camera (45° mirror)
    2. Make an X-ray burn
    3. Assure that the burn mark is at the expected location at IP
  2. Install the wavefront sensor (WFS) grating. 
    1. The mount has been aligned with back reflection of the beamline He-Ne to make sure it is perpendicular to the beam. 
    2. The tilt and jaw are not critical. 
    3. The in-plane rotation angle is more important b/c of the Talbot algorithm. 
  3. Look at the WFS image with the downstream camera
    1. Assure the KB mirror edge
    2. Assure the slits edge 
    3. Make the WFS image centered
  4. Using Matt’s algorithm/GUI to see the Fourier transform result
    2. Adjust KB mirror’s pitch to minimize the high order aberration (make the bottom three plots as close to 0 as possible. For the H and V High Order Lineout, it’s more important for the center part than the outer parts to be close to 0. 
    3. At the same time, we also want the Focus position (in Z) for the H and V to be the same. 
    4. Sometimes it is impossible to only adjust the KB mirror’s pitch, we might need to adjust one of the KB mirror’s locations to compensate for the focus postion’s difference in Z. 
  5. We should have a good wavefront once this is done. 

Find best Z using Imprints

  1. Imprint target: thin gold film on glass substrate
  2. Use 10-30% transmission to make a few fiducial marks.
  3. Test the translation stage x and z travel range. 
  4. Scan x and z with various transmissions (10e-3 to 10e-7)
    1. Syntax: RE(bp.rel_scan([seq],x.sample_x,0,-2.5,x.sample_z,-2,2,51))
    2. Modify the scan range accordingly: RE(bp.rel_scan([seq],x.sample_x,0,-5,x.sample_z,-4,4,101))
  5. Check the imprints under the Olympus microscope upstairs:
  6. We should see some imprints disappear while the Z is off. If we see all imprints show up, it could be: 
    1. The scanning range is not right and we should modify accordingly
    2. The pulse energy is too high, we should add more attenuation to lower the transmission 
    3. When the wavefront is optimal, we should be able to see imprint at good Z locations with down to 10e-7 transmission