From HFML-FELIX Wiki
Cavity dumping
[edit | edit source]A 75 micron thick Silicon film can be rotated in and out of the FELICE optical beam (in Molecular Beam line). It can be moved by a stepper motor, which has no read-back, and should remain powered-off as much as possible to avoid overheating, so the procedure to find Brewster's angle is slightly complicated.
Homing the cavity dumper slab
[edit | edit source]- Move the Molecular beam table to a position roughly half way. For very accurate measurements: ensure the upstream bellow length is 316 mm.
- Switch on the stepper motor driver. Rotate the slab until you see a HeNe spot emerge vertically from the ZnSe Brewster window. Optimize it so it coincides with the cross-hair positioned on the ceiling. This is your zero.
Slab orientations
[edit | edit source]| Position | Description |
|---|---|
| 0 | Brewster's angle (HeNe hits ceiling) |
| -3300 | Slab parallel with optical beam |
| -24400 | Maximum opening for optical beam transmission (slab fully out) |
Notes
[edit | edit source]- Don't forget to switch off the stepper motor driver to avoid over heating it!
- After finishing a cavity-dumping shift, re-orient the slab to the 'Maximum opening' position (see table)
