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[Ketzaltlipoka]

Vaya! Ahora que vengas para acà tendràs que enseñarme como hacer esos trucos, Jorge. Se ven muy chingones,!!!

[johnm]

Now, if I could only get rid of the string . . .

So just for fun here is our tinyest top being controlled without a string.


It is an oddly shaped crystal of Iceland spar (calcite=calcium carbonate) about 1-3 micrometers on a side trapped in a focused laser beam (commonly called a laser tweezer).  By controlling the polarization of the incident laser on this birefringent material, we can controll the direction and to some extent the speed of rotation.

This was taken a couple years ago when we assembled the parts for this experiment in our senior physics lab.  Unfortunately, although many students have since built the tweezer, I'm the only one to have successfully coupled the angular momentum of the laser to a particle with our set up--must be all my experience with tops.

[ta0]

  This board blows my mind! Thanks for posting!

John, you must be the person who has built and spun the largest range of tops ever: from 10" all the way to (say) 2.5 microns:  250mm/0.0025mm = 100,000 or 5 orders of magnitude!!!

In addition, you rotated it with polarized light which is another way of saying the "spin" of photons!!!

Without getting too deep,  , are you using left and right circularly polarized light to impart momentum to the particle in both directions? Or are you just using linearly polarized light that you manually rotate and the particle follows?

[the Earl of Whirl]

That is amazing!

[Dick Stohr]

Without getting too deep,  , are you using left and right circularly polarized light to impart momentum to the particle in both directions? Or are you just using linearly polarized light that you manually rotate and the particle follows?

John, I really do not want to know.
I am just glad you did it!!!!!!!!!!!!!!!!!!!!

[Pulpowsky]

¡Virgen santa!

Este foro es la Hxxxxx.

My god!

This forum is superb!

[johnm]

  Dick, don't read the following! 

Without getting too deep,  , are you using left and right circularly polarized light to impart momentum to the particle in both directions? Or are you just using linearly polarized light that you manually rotate and the particle follows?

You've got it Ta0, we start with linearly polarized light and convert to right and/or left circularly polarized light by rotating a 1/4 wave plate.

[ta0]

Thanks for the explanation, John.

I don't have an optical tweezer at home but I did have some Iceland Spar crystals laying around  . So . . . here is a picture of a top I just improvised with two crystals. It is not a great spinner but it is more than 10,000 times the size or 1,000,000,000,000 the weight of the Cincy top! 

[johnm]

Nice picture Ta0.  With the double image of the number "2" written on the pencil you've clearly shown everyone the birefringence (two refractive indices) of this material.  This lack of crystal symmetry allows us to transfer the angular momentum of the light to the particle.

[Neff]

...brain... hurts...

[the Earl of Whirl]

It appears that Neff is not the only one with someone following him!!!

[ta0]

Nice! 
He is a good player as you can see on another video in which he does a freestyle.

I believe he contacted me once before. I need to check on that.