User:Andy Maloney/Notebook/Lab Notebook of Andy Maloney/2009/07/06/1064 Optical Tweezers

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Beam alignment

The first thing I wanted to check was the beam alignment. I did the exact same procedure I did on Friday to ensure that the beam is still aligned. And yes, it is.

I also wanted to ensure that it stays that way so I'm letting it warm up. While it warms up, I noticed that the condenser did not sit properly in the ø2" lens tube. So, I took it to the machine shop and ground the lens holder down a little bit so that it fit properly. I am still on a knife's edge for deciding if I want to patent my condenser design or if I want to give it to Thorlabs so that another graduate student doesn't have to make their own. Decisions...decisions... On the one hand I need to boost my resume but, on the other, it would be nice to buy the item from someone.

Even after 30 minutes of warm up time, the beam is still aligned.

Detector Stage

I've reassembled the detector stage and put in the 690 nm dichroic mirror. The spectrum we have for the mirror stops at 950 nm but, at 950 nm the transmission is pretty low so it seems that we can use it for our mirror. In the future, we may want to get a 2" diameter dichroic for 1064 but who knows.

Steering Optics

I installed the steering optics and I have been playing around with them for some time now. The worst thing is trying to position them such that the trap is close to the cover slip. I don't have a lot of experience doing this but, I am getting the hang of it. Here's what I did with the steering optics:

  • I actually put in the second lens first. Typically you never do this in optics however, I know the second lens will be fixed while the first one will be used to steer. This means that the first lens will move with respect to the optical axis and the second will not. So, I think it is justified to put the upstream lens in first and adjust it so that the beam does not move from its original position.
    • I should note that this is not the way I did it initially. I first did what my intuition told me which was to put in the downstream steering lens in first. This ended up in me wasting about an hour trying to get things to work.
  • After getting both of the optics in, I started playing around with getting the trap close to the cover slip. This is where I will need the experience of Koch because I just can't seem to get it to work.