User`s manual

16
STRETCHER GRATING ALIGNMENT.
1. Replace the rotation stage with the grating G1. Set position of
rotation stage to “0”.
2. With rotation stage set so that the zero order beam from the
stretcher grating goes back through aperture A1, adjust the
vertical and horizontal tilts of the grating mount for best
alignment to aperture A1.
3. Set rotation stage at 14 degrees for 800 nm. Littrow (auto
collimated) diffracted beam should go back through A1.
4. If not, adjust rotation of the grating about it‟s face for best
vertical alignment to the A1. These is done by carefully
loosening the retaining screw in the grating mount so that the
grating holder can be rotated in the mount . Caution: grating
holder can fall from tilt stage if this step is not performed
carefully or if retaining screw is too loose..
5. Reiterate between step 2 (adjust only the vertical tilt of the
mount) and step 3 (adjust only the rotation of the grating) until
no further adjustment is necessary.
STRETCHER MIRROR ALIGNMENT
1. Operate the Ti : sapphire laser in continuous wave regime at
800 nm.
2. Rotate stretcher grating angle so that first order diffracted
beam hits the center of mirror SM. The beam height must be
maintained at 120 mm. The distance from SM to the center of
stretcher grating G1 should be 35 cm. The angle between input
and diffracted beams is equal 14 degrees (rotation stage position
should be approximately at 21 degrees).
3. Adjust mirror SM, so that reflected beam hits the center of
mirror PM. The distance from the mirror SM to the mirror PM
should be 70 cm.
4. Adjust mirror PM, so that reflected beam hits the mirror SM
at the height of approximately 114 mm. The second reflected
from SM beam will hit the stretcher grating at the height of 114
mm. The second reflected from G1 beam hits the lower mirror
of the stretcher vertical retroreflector VR1. Exiting
retroreflector, the beam hits the G1 at the height of 126 mm and
reflected beam hits the SM at the height of 126 mm, too. The