User:Pranav Rathi/Notebook/OT/2010/08/02/x & y Signal Drift Issue
Investigate the x & Y signal drift: What is causing it; AOM or the laser (most probable it’s the AOM), magnitude of the effect, and possible solution.
Setup & procedure
The setup is fairly simple; laser --> AOM --> two mirrors (down and upstream) --> telescope (1:1)--> QPD.
- Measure the beam waist (2 x W=1.5) at the eyepiece lens of the telescope.
- Setup the (1:1) telescope: In this case two planoconvex lenses (f=38.1mm of both) are used.
- Measure the beam waist again (2 x W =1.5) at QPD, to make sure that the ratio is 1:1.
- Straighten the beam after the telescope, using two aperture techniques [].
- Setup the QPD on the xyz translation stage.