A ruby laser is a solid-state laser that uses a synthetic ruby crystal as its gain medium. The first working laser was a ruby laser made by Theodore H. "Ted" Maiman at Hughes Research Laboratories on May 16, 1960.
A ruby laser rod. Inset: The view through the rod is crystal clear
Maiman's original ruby laser
Components of original ruby laser
Ruby laser pistol constructed by Stanford Univ. physics professor in 1964 to demonstrate the laser to his classes. The plastic body recycled from a toy raygun contained a ruby rod between two flashtubes (right). The pulse of coherent red light was strong enough to pop blue balloons (shown at left) but not red balloons which reflected the light.
A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers, called laser diodes.
Laser rods (from left to right): Ruby, alexandrite, Er:YAG, Nd:YAG