OPT: Optical Tweezers

Laser trapping of neutral particles is a powerful tool for studying everything from atoms to bacteria. Optical Tweezers are a trapping method for microscopic particles, and with our new apparatus you will initially try to trap and study the forces on microscopic plastic spheres.

Write-Up in Word (docx) and PDF Format.

(The experiment is currently located in MP248; last write-up revision: September 2021.)

SAFETY!

This apparatus must not be disassembled in any way. It contains a powerful laser that could damage your eyes if the apparatus is altered in any way. You must receive safety instruction from the supervising professor before touching the equipment.

Some additional resources:

• A tip sheet written by student Yu Xian Peh (October 2019).
• An American Journal of Physics article by M.S. Rocha (2009) on "Optical tweezers for undergraduates: Theoretical analysis and experiments"
• Bead tracking software written in Python by student Jamie Woodbury (2011)
  • Spot Tracker Read Me
  • SpotTracker.py spot tracking Python program (requires Python Imaging Library)
  • SpotTrackerTools.py required for SpotTracker.py
  • TrappedBead.tif a 5MB sample image file with 94 frames of one bead.
• Other student written bead analysis software written in Python (Michael McLean 2021; Christopher Dydula & Jamie Woodbury 2011)
  • Optical Tweezers Analysis Software ReadMe
  • OpticalTrapVideoAnalysis2.py
  • PILBeadTracking2.py
  • TrapAnalysis.py
  • BeadTrackingToolsEdit1.py
• Thorlabs manuals
  • OTKB - Optical Tweezers Kit User Guide
  • OTKBFM - Back Focal Plane Detection Module User Guide
  • PM100D - Optical Power and Energy Meter Operations Manual
  • ITC510 - Laser Diode Combi Controller
  • 19590-M01 - Optical Trap Application Setup (Original Thorlabs guide when this experiment was developed.)

Optical Tweezers Apparatus