15.3 Solutions
763
Brewster windows are used in laser technology (Fig. 15.37). The tubes of gas
lasers are sealed by mounting them in such a way that laser light is incident
at Brewster’s angle. Mirrors mounted outside the tube reflect the light back
and forth through the tube. A small hole in one mirror permits the laser light
to leave. Because the windows are tilted to the axis such that light is incident
at Brewster’s angle, the parallel component can traverse back and forth in the
tube with minimum attenuation. The perpendicular component after several
traversals gets substantially attenuated. Thus the light leaving the laser is
polarized in the parallel direction
tan θ B = μ = 1.5
∴ θ B = 56.3
◦
, which is also the inclination of the Brewster window.
763
Brewster windows are used in laser technology (Fig. 15.37). The tubes of gas
lasers are sealed by mounting them in such a way that laser light is incident
at Brewster’s angle. Mirrors mounted outside the tube reflect the light back
and forth through the tube. A small hole in one mirror permits the laser light
to leave. Because the windows are tilted to the axis such that light is incident
at Brewster’s angle, the parallel component can traverse back and forth in the
tube with minimum attenuation. The perpendicular component after several
traversals gets substantially attenuated. Thus the light leaving the laser is
polarized in the parallel direction
tan θ B = μ = 1.5
∴ θ B = 56.3
◦
, which is also the inclination of the Brewster window.