Optical Tweezers

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Optical Tweezers

• Brandon S Bentzley
• Advised by Dr. Ochoa

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Overview

• What are optical tweezers?
• Physics behind the optical trap
• Why do we need optical tweezers?
• My optical tweezers
• The Setup
• The Tweezed
• Pictures
• Feature Presentation
• My dual beam tweezers
• The setup
• Pictures
• Special Presentation
• Conclusions

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What are Optical Tweezers?

• A way of grabbing very small objects.
• Objects are trapped by a laser beam focused with
  a microscope objective.
• We see whats going on with a CCD camera.

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The Physics

• The Ray Optics Regime
• Wavelength of the laser ltlt Size of the object
  being trapped
• nmedium ? nsphere
• The photons change direction and therefore
  momentum.
• change in momentum gradient force
• reflection of photons scattering force
• For a stable trap to exist the gradient force
  must have a maximum greater than the scattering
  force.

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Why Do We Need Optical Tweezers?

• Biomedical applications
• A non-invasive method for trapping and
  manipulating microscopic biological samples
• Pharmaceutical applications
• The study of the effects of drugs on the
  molecular level
• Physics applications
• Provides an accessible testing ground for
• ideas at the atomic scale

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My Optical Tweezers
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The Setup
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What I am Tweezing

• Polystyrene (CH2CHC6H5) spheres with a diameter
  of 6 micrometers
• A greater index of refraction than the
  surrounding water, n1.55
• Used for a myriad of purposes

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Pictures
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Mike and I carefully building the optical
tweezers setup.
I am diligently correcting the inches side of a
meter stick with an argon laser.
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Feature Presentation

• Rated NC-17 for the touching of spheres by laser
  without consent. Should only be viewed by a
  physics major.

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Encore Presentation
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Dual Beam Optical Tweezers

• The initial laser beam is split into two separate
  and independently controlled beams in order to
  capture two objects simultaneously.
• Used for applications where two objects need to
  be brought together

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Special Presentation
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Conclusions

• Accomplished
• Mastered the science of building and operating
  optical tweezers
• Wrote a manual intricately describing the
  construction of the tweezers
• A trap with more than a two minute duration
• Multiple captures and multiple alignments
• Simultaneously capturing multiple spheres with
  independent lasers
• Will Accomplish
• Use of the argon laser
• An application for our tweezers

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Questions?

• I really know what I am talking about.
• Come on guys I know there are more
• OK I know whats going on here

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Shouting Out Some Love to

• Dr. Ochoa
• Provost Briggs
• Dr. Hirsh and the rest of the chemistry team
• Mike Richman and Hvasta