Opto Sigma red helium neon (He-Ne) lasers are designed for multi-purpose applications such as confocal laser scanning microscopy, spectroscopy, basic research, or education. They are available with polarized or non-polarized outputs in powers from 0.5 to 20 mW. Power supplies are sold separately. These lasers have a robust mechanical design, excellent beam quality and long service life, up to 20,000 hours. Customized models are also available in the spectral range red, green and yellow with output powers between 0.5 and 35 mW. Options are single mode or multimode output, random or linear polarization and Brewster window tubes for educational and scientific purposes.