Abstract: An optical Faraday isolator includes a slab of Faraday rotator medium coated to define input and output faces and internal reflective surfaces for causing the beam to travel between the input and output faces along a zig-zag path. Permanent magnets polarized in a direction normal to the plane defined by the zig-zag beam path are disposed on opposite sides of the beam path. The magnets are paired on each side with serially alternating polarity and the like poles are in transverse registration on opposite sides of the beam path to produce an intense, unidirectional magnetic field parallel to the beam path within the rotator slab. A quarterwave plate introduces a compensating amount of elliptical polarization to cancel unwanted elliptical polarization effects of the slab and its coatings. A beam shaving aperture at the exit of the slab shaves off divergent backward travelling rays.

Abstract: A meniscus lens is disclosed for use in high power light beam applications, such as in the optics of a high power laser where the laser beam intensity is in excess of one megawatt per square centimeter. The meniscus lens is designed such that light rays reflected from the lens are divergent so that no back focal points are created by the lens. In this manner, undesired dielectric breakdowns and damage to optical components and the like are avoided due to reflected back focal points. In one embodiment of the present invention, the output mirror of a high power laser is deposited upon the convex face of a meniscus lens, such lens being designed to avoid back focal points, whereby the construction of the output mirror is greatly simplified.