LASER POLARIZATION MODULATION TECHNIQUES

1,038,329. Lasers. INTERNATIONAL BUSINESS MACHINES CORPORATION. Feb. 11, 1965 [Feb. 28, 1964], No. 5905/65. Heading H3B. In order to produce a beam of polarized light from a laser a magnetic plate is inserted in the optical cavity to reflect light between one of the cavity reflectors and the active medium so that when the surface of the plate is magnetized the light is elliptically polarized when reflected due to magneto-optic effects. In the arrangement shown a magnetic plate 3 is inserted in the optical cavity 2, 6 of a ruby laser 1 so that when the plate 3 is magnetized in a direction parallel to the plane of incidence of the light from rod 1 and in the surface 4 then after a number of reflections the light becomes fully elliptically polarized in a direction depending on the direction of magnetization, Fig. 3 (not shown). In order to compensate for the effect of metallic reflections on the polarization of the light produced mirror 8 is inserted in the light path between plate 3 and mirror 6 arranged in a plane normal to the surface 4 and at an angle of 45 degrees to the plane of incidence of light acting on surface 4. The surface 4 may have different areas magnetized in different directions, Fig. 8 (not shown), so that the output beam has portions corresponding to the areas polarized in one direction or the other.