User:Anthony Salvagno/Notebook/Research/2010/08/23/More laser learning

We are trying some new methods to characterize our beam.

Beam Waist
The results we were getting on Fri are consistent with half of what we should be getting. So we think that the razor blade method actually gives you the beam radius instead of the diameter. Pranav spoke to a friend of his and verified this. We are now trying to measure the beam diameter with a circular aperture instead. We think we can get the proper radius by closing the aperture to get 86% of the power and then measuring that diameter. Pranav said he has a program that can find the beam waist location based on two points. According to the program the beam waist is smallest at ~420mm and we measured it there to be 1.7mm so we are scrapping this and doing the razor blade method every 3in to get some better results.
 * 45mm away -> 1.6mm diameter
 * 825.5mm away -> 1.39mm

Beam Power
We haven't really measured 2W from this laser yet. We borrowed a power meter from next door and using theirs we got 1.8W and then we tested it on the old laser to see if we could get accurate numbers. We got 2W when the laser was set to 2W. We then calibrated our power meter to give us 2W and tested it at different powers, which we got the correct values for. Finally we measured the new laser and got ~1.7W which isn't great but better than the 1.5 we were reading this morning. By the close of business on Fri we were reading 1.5 as well (which is no good).