an introductory information about optical tweezers
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An Introductory Information about Optical Tweezers. Mustafa Yorulmaz Koç University , Material Science and Engineering. Outline. History of optical tweezers Basics of optical tweezers Physics beyond optical trapping Types of optical tweezers Possible uses and research areas - PowerPoint PPT PresentationTRANSCRIPT
An Introductory Information
about Optical Tweezers
Mustafa Yorulmaz
Koç University,
Material Science and Engineering
February 20, 2008 Koç University, Material Science and Engineering
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Outline
History of optical tweezers Basics of optical tweezers Physics beyond optical trapping Types of optical tweezers Possible uses and research areas A typical setup of optical tweezers Illustrative examples from our laboratory
February 20, 2008 Koç University, Material Science and Engineering
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History of Optical Tweezers
The technique of trapping was first applied in 1984 at Bell Laboratories
In 1986, they showed a demo of optical tweezers
They showed the damage-free manipulation on cells using an infrared laser in 1987.
1970 - Optical Tweezers: A. Ashkin (*)
(*) http://www1.bell-labs.com/org/physicalsciences/timeline/1970_ashkin_pop.html
February 20, 2008 Koç University, Material Science and Engineering
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Basics of Optical Tweezers Optical Tweezers are examples of optical trapping which is a
subfield of laser physics. They are used to trap and manipulate particles (in range from m
to nm) and also to measure the forces (in range from 1 to 100 pN) on these particles
A strongly focused laser beam is used for trapping the particles. The particles that are of interest has to show dielectric property.
* http://www.physics.uq.edu.au/lp/tweezers/papers/nieminen2001jqsrt70/
February 20, 2008 Koç University, Material Science and Engineering
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Physics Beyond Optical Trapping Trapping occurs due to radiation
pressure of laser which results by the momentum change of light.
There are two forces that let the particle to be hold in trap: Scattering force: due to reflection of
light (to push object) Gradient force: due to refraction of
light (to pull object)
nparticle>nmedium so that Fgradient>Fscattering
Using high NA objectives and high power lasers maximizes the trapping force.
Schematic diagram showing the force on a dielectric sphere due to both reflection and refraction of two rays of light.
February 20, 2008 Koç University, Material Science and Engineering
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Types of Optical Tweezers
Single beam optical tweezers
Holographic Optical Tweezers
Experimental setup for our aerosol holographic tweezers
http://people.sabanciuniv.edu/meric/projects/twz1.jpg
http://www.dundee.ac.uk/elecengphysics/tweezers/Research/aerosols_HOT.htm
Dual beam optical tweezers
http://www.the-scientist.com/article/display/15545/
http://www.ffn.ub.es/ritort/research.html
February 20, 2008 Koç University, Material Science and Engineering
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Possible uses and research areas
By using optical tweezers, it is possible to study and manipulate particles like
atoms, molecules and small dielectric spheres (in range from m to nm).
make force measurements of biological objects in piconewton range.
Dielectric objects are attracted to the center of the beam, slightly above the beam waist, as described in the text. The force applied on the object depends linearly on its displacement from the trap center just as with a simple spring system.
http://www.answers.com/topic/optical-tweezers?cat=technology
Optical tweezer for force measurements
In the lasest research; this technique has been used forbiological investigations involving cellscutting and ablating biological objects (cell fusion and DNA cutting)force measurements of cell structures and DNA coilingelasticity measurements of DNA
So, optical tweezers has opened up several important new areas of study in biophysics
February 20, 2008 Koç University, Material Science and Engineering
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A Typical Setup of Optical Tweezers
CCDCCD
Collimationf1f2
M1
M2 M3
M4
f5O1
Telesentricf4f3
ComputerComputer
MicroscopeMicroscope
IlluminationIllumination
Nd: YAG Laser (1064nm)Nd: YAG Laser (1064nm)
February 20, 2008 Koç University, Material Science and Engineering
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Illustrative Examples From Our Laboratory: Manipulation of Microspheres
Thanks to Ahmet Faruk Coşkun
February 20, 2008 Koç University, Material Science and Engineering
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Illustrative Examples From Our Laboratory: Manipulation of Vibrio Cholerae
Thanks to Ahmet Faruk Coşkun
February 20, 2008 Koç University, Material Science and Engineering
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Thanks..
Questions?