Brewster window losses in 6328 A He-Ne lasers

Optical losses introduced in a He-Ne laser cavity by a BSC glass window around the Brewster angle have been estimated. Absorption losses within +or-45' of the Brewster angle are found to be nearly constant and predominantly large compared with the reflection losses. Contrarily, the presence of skew angles increases the reflection losses which become comparable to the absorption losses at a skew angle of about 30'.