User:Andy Maloney/Notebook/Lab Notebook of Andy Maloney/2009/06/27/1064 Optical tweezers

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Setup change

Today I came in thinking I could move the microscope myself. Dumb dumb dumb... At any rate, I fussed with the 1064 optical tweezers today and I had to make a modification to the setup. Before I modified the setup, I played around with the output power of the laser and looking at the optical axis I made yesterday to see if the beam would deviate with power. I didn't find any conclusive evidence that it did but I kept working with it above 1 W.

The modifications I made where as follows:

As you can see, I had to move the power modulator from yesterday. I had to do this because the entrance and exit pupils do not live on the same plane.

I didn't realize this at first. So, I wasted time trying to see what was going on. An hour wasted when I should have looked at the specs of the thing before I started fussing with it.

Grrr... Why do I keep teaching myself this lesson? Well, it was only an hour...

After realizing this, I decided that I wanted to maintain a nice optical axis so I opted to put the power modulator before the mirrors. I think the power modulator has built in ND filters but, I don't know what the OD of them are nor do I know how to use them. I'm guessing that they are controlled by the only knob on the thing.

After realignment, I put in the 10X Galilean Beam Expander. This guy is mounted on a XY stage pieced together from parts and a 2" kinematic mirror mount. This is so I have the ability to move the expander up and down, left and right, and pitch and yaw. Aligning the beast was a bit cumbersome but I did it. Here's what I did:

  1. Mount an iris on the expander entrance pupil.
  2. Close the iris so that I could only see the outer edge of the beam around the open iris with the infrared viewer.
  3. Adjust the X and Y position so that the beam is in the center of the iris.
  4. Open the iris and view with the camera the position of the beam. The camera was close to the expander and was centered.
  5. Move the camera away from the expander and see where the beam moved to.
  6. Adjust pitch and yaw.
  7. Close iris and see how changing pitch/yaw affected the XY position. Change accordingly.

I have no idea if this is the best way to do this, but in the end it worked. I just iterated the last steps until my beam did not deflect any with the expander in place.

To do

  • Move the microscope into the new lab.
  • Setup the periscope.
  • Add steering optics.
  • Tweeze!

Koch question: Do we have another dichroic mirror for 1064 that will mount into the cage cube I designed?

Steve Koch 23:55, 27 June 2009 (EDT): I think probably, but I'm not sure. You'll have to check with Larry. I thought we did.