Thursday, March 20, 2008

Finished!


I did my final presentation today - I'm finished my project! I still have to write my report for next Friday, but I have no more classes this term. I think my talk went pretty well overall. I wish I had been asked more questions - I had so much to say!

I did run the 980nm laser through the taper yesterday. I observed the exact same effects as with the 1460nm laser, but the fibre was not jumping (which is good). An example video is shown below with a modulated field and oscillating clump of beads. The camera can sense the 980nm light so we can see visually when the light field switches on and off.

4 comments:

Anonymous said...

Apparently, it is not evanescent wave working on these beads. This is really strange. Congradulations of finishing your report!

alphaLaura said...

Thanks - I'm delighted to be finished!

I wish I knew what was causing this. I just hope it's not something very trivial.

Anonymous said...

I can't start imagining what is causing this. Are your bead electrically charged? what is the size of them? The movement seems to be too fast to be due heat exchange.

I don't think this is a typical optical tweezers experiment. I'm not an expert, but I understand those use sub-micron particles and tend to trap them inside the beam.

alphaLaura said...

Hi there opt-tech,

These beads weren't electrically charged - they were, as far as I can recall, made from some sort of polymer. Approx 5 micrometers in diameter.

Yes, the aim of the game was to trap the beads in the field. I should have observed the nearby beads being pulled towards the fiber and along the fober in motion with the evanescent field.