Practical example: slits alignment

Info

The objective of this example is not to teach a specific alignment procedure for slits but rather to demonstrate how to the interaction with flint works and how to define offsets on motors.

The procedure presented below is based on the following main steps (in case there are other ways to align slits…):

  1. Define the 0 position of the hardware motors at half beam position to define gap = 0
  2. Scan slit_offset at a small gap opening to find the 0 position of slit_offset.
  • Get a first image in flint to see, if slits are aligned … gap not closed even though slit_vertical_gap = 0
DEMO_SESSION [1]: ct(.1,beamviewer)
  • Open gap to large extend using the hardware motors
DEMO_SESSION [2]: umv(slit_top,3,slit_bottom 3)

  • Aim of the next steps: align the hardware motors to the half beam position to define slit_vertical_gap = 0

  • Scan top blade and align half beam position

DEMO_SESSION [3]: ascan(slit_top,-2,2,20,.1,beamviewer)
         Out [3]: Scan(number=4, name=ascan, path=/tmp/scans/demo_session/data.h5)

DEMO_SESSION [4]: cen(beamviewer.counters.roi1_sum)
DEMO_SESSION [5]: goto_cen(beamviewer.counters.roi1_sum)

DEMO_SESSION [6]: plotselect(beamviewer.counters.roi1_sum)

DEMO_SESSION [6]: goto_cen()

DEMO_SESSION [7]: slit_top.position=0
  • Now slit_top is aligned, move it out of the way and repeat the same procedure for slit_bottom
DEMO_SESSION [9]: umv(slit_top,3)

DEMO_SESSION [10]: ascan(slit_bottom,-2,2,20,.1,beamviewer)

DEMO_SESSION [11]: goto_cen()

DEMO_SESSION [12]: slit_bottom.position=0
  • Now slit_bottom is aligned as well. Move both hardware motors to 0 postion, which is equivalent of closed gap
  • Now set slit_vertical_gap = 0
DEMO_SESSION [13]: umv(slit_top,0)

DEMO_SESSION [14]: loopscan(1,.1,beamviewer)
         Out [14]: Scan(number=6, name=loopscan, path=/tmp/scans/demo_session/data.h5)

DEMO_SESSION [15]: wa()
Current Positions: user
                   dial

     sy    sz[mm]    slit_top    slit_bottom    slit_vertical_gap    slit_vertical_offset
-------  --------  ----------  -------------  -------------------  ----------------------
0.00000   0.00000     0.00000        0.00000              0.00000                 0.00000
0.00000   0.00000    -0.43800        0.05600              0.00000                 0.00000

DEMO_SESSION [16]: slit_vertical_gap.position = 0
  • Open gap a little bit to be able to scan the offset
DEMO_SESSION [17]: umv(slit_vertical_gap, .1)

DEMO_SESSION [18]: ascan(slit_vertical_offset,-2,2,40,.1,beamviewer)

DEMO_SESSION [19]: goto_cen()

DEMO_SESSION [20]: wa()
Current Positions: user
                   dial

     sy    sz[mm]    slit_top    slit_bottom    slit_vertical_gap    slit_vertical_offset
-------  --------  ----------  -------------  -------------------  ----------------------
0.00000   0.00000     0.07000        0.03000              0.10000                 0.02000
0.00000   0.00000    -0.36800        0.08600              0.10000                 0.02000

DEMO_SESSION [21]: slit_vertical_offset.position=0
  • Now the slit (slit_vertical_gap and slit_vertical_offset) should be aligned.