1. The SPELEEM must be in imaging mode, field of view of 20 µm. The large energy slit must be inserted, to allow proper imaging of the beam shape. Otherwise, the dispersion of seconday photoelectrons will make it impossible to understand its real size.
   
   
2. Not to burn the detector with intense secondary electron yield, make sure that the contrast aperture is inserted. Umeasure/Uview must be up and running, with the frame grabber in preview mode, exposure less than 20 msec.
   
   
3. Open the beamline and select appropriate photon energy and undulator gap. Check that the deflection mirror sending the beam to the other branch-line is not inserted (and vice-versa for the other branch-line!)
   
   
4. The alignment of the photon beam is done from UMeasure, using the beamline alignment panel of the beamline controls window. Start with the beam alignment checkbox, selecting "horizontal", corresponding to the HRM PITCH of horizontal refocussing mirror. The HRM ROLL shown in the figure is normally not be activated.
   
   
5. In order to find the beam, it is convenient to scan the pitch of the horizontal refocussing mirror (HRM pitch). Up to a few hundreds steps typically necessary to find the photon beam. Do not move the vertical refocussing mirror (VRM pitch), before finding the beam. If the intensity on the detector is low, decrease the start voltage down to few eV, in order to detect more easily the secondary emission at the margins of beam spot. But, be ready to quickly increase start voltage if the intensity on the detector gets too high when you find the central part of the photon beam. If there is no signal at all on the detector, you can also image a larger field of view.
   
   
6. Once you find the beam, maximise intensity using the HRM pitch and VRM pitch.
   
   
7. Only expert users should change the "beam focusing", which is normally set by the beamline personnel. Normally few tens steps are enough to focalise the beam to few microns in the vertical direction and obtain a relatively homogeneous illumination of the sample.

IMPORTANT

NOTE: The alignment of the refocussing section is very sensitve to HRM and VRM roll. To avoid accidental misalignment, HRM and VRM roll are not activated in Umeasure. Deviation on the ideal roll value enlarges and tilts the beam. To properly align the beam, do the following:
1) Move HRM ROLL in steps of 50 and compensate with VRM pitch, until the beam moves along the vertical direction.
2) Optimise vertical focus.
3) Move VRM ROLL in steps of 50band compensate with HRM pitch, until beam moves along the horozontal direction.
4) Optimise horizontal focus.