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5) Adjust the positions of the enterance and exit irises at the beginning and end of the PPC so that the beam passes centeres through them.
6) Adjust height and lateral position of first two mirrors and ensure mirrors such that the beam hits both of them in the center. Then adjust the orientation of the mirrors so that the exiting beam direction is normal to entrance beam.
7) Position the large silver mirror such that the beam is centered on it, and adjust the mirror position such that the reflected beam is parallel to table and then adjust its angle it is entering prism close to its far edge.
8) Now adjust angle of prism to find the angle of minimum deviation using rotation stage (coarse). Do this by placing an IR card far away and rotating prism to find angle where beam is furthers to the right.
9) Now make sure reflected beam and incident beam are coplanar by adjusting the angle of the prism and looking at the height of the reflected beam on the IR card. The reflection is very faint and needs an IR viewer to be seen.
10) Now make sure the refracted beam is coplanar with the reflected and incident beam by adjusting the other angle of the prism.
11) Redo finding angle of minimum deviation using fine adjustment. This will be the angle where the beam is the rightmost possible.
12) Algin retroreflector axis. Adjust height of retreflector such that the return beam is centered on the roof mirror. Then adjust close side of rail such that the returning beam is hitting the prism a little further into the prism (2 to 3 mm). Then adjust the back position such the rail is exactly parallel to the beam. Slide the retroreflector back and forth along the rail to check that it is moving along the axis of the beam.
13)
Pockels cell
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2x table beam expander
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