What is a Brewster Window?
for more information. Lasers with external mirrors and Brewster windows (plates at the Brewster angle attached to the ends of the tube) will be linearly polarized and really expensive. They will also be more finicky as there may be some maintenance – the optics will need to be kept immaculate and the mirror alignment may need to be touched up occasionally. However, the fine adjustments will permit optimum performance to be maintained and changes in beam characteristics due to thermal effects should be reduced since the resonator optics are isolated from the plasma tube. Some HeNe lasers have an internal High Reflector (HR) mirror at one end of the tube but a Brewster window and external Output Coupler (OC) mirror at the other end. These are also linearly polarized and only half as finicky. 🙂 In the trivial triviality department, the largest commercial two-Brewster laser I know of is the Spectra-Physics model 125, rated at 50 mW (red, 632.8 nm) but often producing much more output powe
