Blue and violet laser pointers

Blue laser pointers, which became available around 2006, have the same basic construction as DPSS green lasers. They most commonly lase at 473 nm, which is produced by frequency doubling of 946 nm laser radiation from a diode-pumped Nd:YAG or Nd:YVO4 crystal (Nd-doped crystals usually produce a principal wavelength of 1064 nm, but with the proper reflective coating mirrors can be also made to lase at other non-principal neodymium wavelengths).
In 2006 many factories began production of blue laser-modules for mass storage devices, and these entered the mass consumer market as laser pointers, as well. There were DPSS type frequency-doubled devices. For high output power BBO crystals are used as frequency doublers; for lower powers, KTP is used. The Japanese company Nichia controlled 80% of the blue laser diode market in 2006.[8]
Blue lasers can also be fabricated directly with InGaN semiconductors, which produce blue light without frequency-doubling. 450 nm blue laser diodes are currently available on the open market. The devices are brighter than the 405 nm laser diodes, since the longer wavelength is closer to the peak sensitivity of the human eye. Commercial devices like laser projectors have driven down the prices on these diodes, as of March 2010.


http://en.wikipedia.org/wiki/Laser_pointer