Particles hitch a ride inside a beam of light

[bluerose]

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--just thought this is cool enough to share----

from link Particles hitch a ride inside a beam of light - Physics Update
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Particles hitch a ride inside a beam of light
By Physics Today

Since its introduction in the 1970s, optical trapping has become a mainstay in science research. It has been used to tug at strands of DNA, to levitate aerosols, and to cool atoms to microkelvin temperatures. It has not, however, been very effective at manipulating light-absorbing particles, particularly in air or other gases. That's because conventional traps rely on radiation pressure, the momentum imparted by refracting light, to pull a particle into an optical beam. But photophoretic forces, which result from the imbalanced momentum exchange between an anisotropically heated particle and its surrounding gas, tend to push an absorbing particle away from intense light. Andrei Rode and colleagues at the Australian National University in Canberra have now developed a technique that exploits photophoretic forces to confine and move light-absorbing particles in air. And unlike conventional techniques that manipulate particles over just millimeter distances, theirs could conceivably send particles gliding across an entire room. The key was to use a Laguerre–Gaussian beam, in which a donut-like ring of light surrounds a dark core. A particle that finds its way into the core, such as the 50-µm carbon-coated glass sphere shown here, gets trapped in the transverse (x–y) plane and propelled in the direction of light propagation (z) by photophoretic pushes. Two beams aimed from opposite directions can hold a particle in place, a potentially useful technique to isolate particles such as carbon soot—a suspected global warming contributor—for sensitive measurements. (V. G. Shvedov et al., Phys. Rev. Lett. 105, 118103, 2010.)—Ashley G. Smart

[bluerose]

Physics enthusiasts and/or Physics students/grads... something we can replicate in our laboratories?? ^_^
I always wanted to try those particle-trapping devices, and prolly do lab research with that topic.. though our thesis more kinda leaned towards optics in the industry.

[fritzd]

Far, naa man ta toy Optical Trapping experiment nga i-setup sa physics department sa? Ingon man to si Sir Mayo, ning-graduate nalang ta, wala gihapon. Actually sayon ra gyud siya buhaton, ang pinaka-simple nga optical trapping setup. I think ang optics lab sa P6 department sa USC kay nana tanan required equipment. hehehe One way kay gamit lang ug optical fibers kay focussed single mode Gaussian beam naman ang gawas sa fiber. Imo lang i-counterpropagate ang 2 beams gikan sa 2 optical fibers. Ang pag-align tingali ang pinakalisod tingali ana. hehehe

[bluerose]

lagi! bisan nalang unta to pinakasimple na particle - trapping set-up.
ipropose kaha ni nila mga students sa? makaya rajud ni.. ^_^ hehe ganahan pud tawn ko mubisita didto if nana kalambuan, or mga new stuff..
medical physics kay in progress na ba? or wala pa gihapon fritz? ikaw man jud nakavisit..

[walaybuot69]

This was supposed to be one (optical trapping) of the thesis of undergrad students during my time (batch 2005) but because of the childishness of the person who brag about being THE ONE, nothing was done. The equipments just sit in the dust.

[bluerose]

so si THE ONE ra ang nakatrap ug particle diay ani...
batch 05 ka? batch 08 mi ang wla pasad mi kagamit ug ingon-ani na set-up..