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Optical Tweezers experiment =]

  1. Mar 24, 2014 #1


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    I'm an undergrad at IPFW and I just got on this project setting up an optical trap.

    Our (my professors) main goal is to find out at what intensity (he keeps saying temperature) of light the objects behave as free particles. I see where this could be of interest, but aren't there bigger things that could be done with this? I don't really know a whole lot about this kind of experiment, or optics really for that matter, but it seems like (especially since it's a rather new field to my understanding) there are a lot bigger questions that could be addressed. Apparently there's a lot of dispute over the proportionality of the force exerted on the objects (all the way from -2 to -5 or -6 if memory serves). This seems like a nice, fun, and rather interesting idea to explore, a little bit of classical physics, a little bit of quantum, a little bit of experimentation, and a little innovation. I have a few ideas for how to try to figure this out,

    but I was wondering:

    What other questions would be good (interesting) to explore? I have a little while (2-3 years) until I graduate, and I have to do a senior project. This field shows a lot of promise for me. It's new, it's mysterious, and interesting. The only thing is, if I go with this, I want to take it as far as I can.

    Any ideas?

    Also FYI: Optical tweezers is, in a nutshell, using a laser to exert a force on an object which, coupled with the intensity gradient of the laser and the normal force from the back plate, locks the object into place and allows for rather significant manipulation. I saw a group, in CERN I believe, play tetris with their objects in demonstration of the traps ability.

    One more question:
    How do you (the community) feel this ties in with heisenbergs uncertainty? Am I the only one looking at this and seeing potential (POTENTIAL) for violating heisenbergs principle at least to some degree?
  2. jcsd
  3. Mar 24, 2014 #2


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    I don't know about the rest, since I'm not into lasers that much... But about Heisenberg's uncertainty principle, oh well... In what sense? If you can reach that precision needed to challenge it with any machine, that would be fun... So far, in any experiment I've been into, I haven't been close enough to care about Heisenberg's uncertainty principle (not even as an error).
  4. Mar 25, 2014 #3


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    Well... we very well may not end up getting that precise, I'm not really sure exactly to what degree we are going to be measuring (I'm just getting on the project), but I do know that we're dealing with nanoscopic scales, and if we took what my teacher's proposing we do (decrease the intensity) and do the opposite, that should increase the intensity gradient, locking the objects in more confined and accurate positions (smaller Δx), and by instigating collisions and interactions, we should be able to know pretty accurately the momentum, not just as a scaler but as a vector, within a good amount of accuracy. Whether or not we will achieve ΔxΔp≤h, is as of yet a mystery; I just see the potential, also I've read results from CERN a few years back that they were reporting results ≈h/2, so as far as I'm concerned, HUP makes sense, and h is an intuitive value, maybe he even mathed it out, but I'm not necessarily buying it as the forementioned inequality.
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