User:Anthony Salvagno/Notebook/Research/2009/10/07/Tweezer Alignment

Sorry for the delay in writing this out. I have been working on this since Friday and just haven't had time to write anything down. But I have got the tweezers working and I can't wait to try and get new data. Here are my notes:

Alignment
If you have the unfortunateness of this task I ask that you take your time. It makes no sense to try and rush the job because it won't get done right. Laziness tried to rear it's ugly head here several times but I wouldn't let it. Anyways here are some useful tricks:
 * Use 2 mirrors to set up an optical axis. The reason for this is because it is easy to adjust the beam path with two mirrors.  My method was to place a CCD on a rail with the rail oriented parallel to my beam path.  This way I could analyze the beam profile along the rail and determine if the path is straight along that line.
 * Place everything on translation stages. This makes it easier to align things into the path of the beam without adjusting posts and screws and such.  You still have to mess with that stuff, but much less so.
 * Iris's can be fun. With an iris you can place the iris in locations where a lens may go and use the center of the iris to locate your beam spot.  If it goes through the center you are good to go.  Using 2 irises creates a line that you want the path to follow.  If the beam spot hits both iris centers than you have a straight line.
 * Cage system works great for lenses. With this you can align everything in a straight line and then add crucial elements once aligned.
 * Periscope setup. For this you place two mirrors in line vertically.  Once the proper angles are formed (45 degrees each is nice) you can translate each mirror to move the beam but still keep the beam path straight.  Moving the bottom mirror up and down will move the beam path left and right.  Moving the top mirror up and down will move the path up and down.

Right now I can't think of much else, but if it comes to me I'll post it.

Tweezers as they are now
Picture to come later. Right now I have a working Optical Tweezers. Changes include placing the periscope closer to the steering telescope, using only 2 mirrors for initial optical path (I think it was like this in the first design), and a new design for the QPD. Originally the QPD was in a cage and on some mics that had a lot of slop to them. Now it is directly on a post attached to a sturdy X-Y translator. Also I made a 15 pin to BNC cable to control the laser from labview. Amazingly it works! That made my night.

Acknowledgments
Special thanks to Andy for all his dedicated work with the Tweezers and for helping me get it set up and showing me how to do it all. I think I am at the comfort level of DIY now.