http://www.kitlaser.com/blue-laser-pointers.html
The roots of modern high end blue laser pen technology go back to a burst of innovation in the years following Theodore Maiman's demonstration of the ruby laser in 1960. Most major types of lasers were first demonstrated in those early years, but their technology has advanced greatly since then and today is on a roll.The next big step in solid-state lasers was laser action on the 1.06-micrometer line of neodymium. Neodymium had particularly good laser properties; developers studied many other crystalline hosts.