Post : Variable frequency laser using shaken ball berings
URL : http://hackaday.com/2012/09/19/variable-frequency-laser-using-shaken-ball-berings/
Posted : September 19, 2012 at 7:01 am
Author : Brian Benchoff
Tags : arxiv, laser, physics, variable frequency laser
Categories : laser hacks

http://hackadaycom.files.wordpress.com/2012/09/laser.jpg

Lasers normally emit only one color, or frequency of light. This is true for laser pointers or the laser diodes in a DVD player. [Kevin] caught wind of state-of-the-art research into making variable wavelength lasers using shaken grains of metal and decided to build his own (http://fabymartin.com/2012/09/makerfaireyyc/) .

When [Kevin] read a NewScientist blog post (http://www.newscientist.com/article/mg21428712.000-shaking-metallic-grains-turns-them-into-tunable-laser.html) on building variable frequency lasers built with shaken metallic grains, he knew he had to build on. He dug up the arxiv article (http://arxiv.org/abs/1205.5977) and realized the experimental setup was fairly simple and easily achievable with a bit of home engineering.

[Kevin]'s device works by taking thousands of small ball bearings and putting them in a small vial with Rodamine B (http://en.wikipedia.org/wiki/Rhodamine_B) laser dye. To vibrate the particles in the dye, [Kevin] mounted his container of dye and bearings on an audio speaker and used a frequency generator to shake the ball bearings.

When a small 30mW green laser shines through the vial of ball bearings and dye, the laser changes color to a very bright yellow. By vibrating the vial at 35 to 45 Hz, [Kevin] can change the frequency, or color of the laser.

[Kevin] can only alter the frequency of the laser by about 30 nm, or about the same color change as a reddish-orange and an orangish-yellow. Still, it's pretty amazing that [Kevin] was able to do state-of-the-art physics research at home.

Sadly, we couldn't find any videos of [Kevin]'s variable frequency laser. If you can find one send it in to the tip line and we'll update this post.

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