Laser wavelength

Steve Knight

The red laser pointers you see are laser diodes, wavelength not particularly well characterised, it varies with operating temperature, ~0.25 nm / deg.  I would recommend a green laser, these are normally diode pumped solid state lasers.  Wavelength always 532nm, determined by energy levels in Neodymium rather than band gaps in a semiconductor.  Blue lasers are diode lasers as well so again wavelength not well characterised.  An old style red gas laser would be good, these are Helium Neon lasers, wavelength always 632.8nm.