Optical Tweezers

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Optical Tweezers

Resources

  • [1] Directions on how to use a QPD in an optical tweezer setup.
  • [2] Here are some slide prepping instructions from Berkeley.

Our own setup

Using NI Vision Assistant

  • [3] Image Acquisition/Saving Images
  • [4] How to track the microspheres in NI Vision Assistant using pattern matching.
    • We recommend not doing it using pattern matching and either brute force point and click track the spheres, or use the QPD to record position. The pattern matching gave variable results.

Our calculations using Brownian Motion

  • 2.56 micrometer spheres
    • 4.6 mW Beam [5]

Calculating Trap Forces Using Stokes' Drag Force

  • [6] iPython Calculations
  • Beam Power (mW) Escape Velocity (microns/second) Trap Force (pN)
    5.5 20.57 0.44
    8.5 33.49 0.72
    11.7 40.00 0.86
    15.3 62.60 1.34
    19.0 84.71 1.82
    23.0 110.77 2.38
    Trap force graph stokes 1.png
  • A simple calculation would say that I need a 10 billion watt laser to achieve a 1 Newton trapping force. We should totally do that. The spheres would be so incredibly trapped.