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. When [Kevin] read a NewScientist blog
post on building variable frequency lasers built with shaken
metallic grains, he knew he had to build on. He dug up the arxiv
article 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 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] c