From Advanced Projects Lab
Optical Tweezers
Resources
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[1] Directions on how to use a QPD in an optical tweezer setup.
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[2] Here are some slide prepping instructions from Berkeley.
Our own setup
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Slide Setup
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Stokes' Setup
Using NI Vision Assistant
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[4] Image Acquisition/Saving Images
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[5] How to track the microspheres in NI Vision Assistant using pattern matching.
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We actually tried both using pattern matching and brute force point and click methods. Neither worked very well, so we recommend using the QPD to get position measurements
Our calculations using Brownian Motion
Calculating Trap Forces Using Stokes' Drag Force
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[7] iPython Calculations
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| 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 |
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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.
Trapping Video
[8]
