User:Anthony Salvagno/Notebook/Research/2010/08/27/Optics and Laser Knowledge: Notes from this week

Here are some notes to make up for lack of notebooking.

New Laser

 * works very well
 * may not be quite 2W but definitely is close. This is still indeterminable since our power meter isn't that good/not calibrated properly
 * definitely NOT multimodal
 * definitely well polarized

Imaging

 * we tried a lot of cool tricks with optics and we used the CCD to find the sharpest image when lenses are in certain positions
 * we would illuminate an object behind the AOM and then set up some kind of optical system. At the end of the whole thing we put a ccd and moved it into a position that we could then sharply see our image. We would put the QPD at this spot.
 * we did a lot with a simple 1:1 telescope (with convex lenses)
 * we were able to fix the qpd drift problem (due to the AOM) with this setup
 * AOM -> L1 (AOM at f1) -> L2 (same lens as L1, distance 2f from L1) -> QPD (at f from L2)
 * next we played with beam expansion, cue equal signs...

Beam Expansion

 * this is mysterious to me, how image planes work with beam expansion
 * I don't think our beam expander (variable) has a conjugate plane because it is afocal (without a focus) because it uses two convex lenses and a negative lens
 * we could never image anything with the beam expander and always needed some lens in front of the qpd. This leads us to believe that you always need some kind of lens between the QPD and the condenser.
 * you can put a beam expander anywhere. We got similar QPD and imaging results if we put the beam expander before our 1:1 telescope or behind it.
 * still would like to work it with a 1:x telescope instead of our variable telescope