User:Anthony Salvagno/Notebook/Research/2009/02/11/Tweezer Alignment

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Designing Path

This is the setup we attempted today. The red lines denote laser path. Notice there are no lenses for beam expansion or steering. Also note... not to scale.

Trapping with the red laser is proving difficult. We think there may be several problems with the setup. First, the laser as measured is less than 10mW which is a very low power. Second, the beam is not spherical it is elliptical which can hinder trapping in one dimension. Another problem is that the camera cannot look at the spot that the laser is aimed at. For some reason the camera doesn't show the whole FOV, but rather some small portion of it (I don't even think it's centered). Also the beam may not be collimated properly.

Anyways we set up a path that was mostly constructed from mirrors. We didn't need a beam expander, because the measured width of the beam was larger than the back aperture. I guess this is good. We just used mirrors to put the beam into the objective and tried to perform a basic tweezing experiment.

Larry prepared a sample of microbeads (I had left some out from a long time ago, January perhaps). We did not achieve trapping. Not much else to say here.