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 … [Read more...]