| 摘要 |
1289154 Polarizing apparatus PHILIPS ELECTRONIC-ASSOCIATED INDUSTRIES Ltd 5 Nov 1969 [8 Nov 1968] 54222/69 Addition to 1185970 Heading G2J [Also in Division H4] The arrangement of Fig. 1 of the parent Specification, which converts circularly polarized light into plane polarized light having a polarization plane which rotates at a constant angular velocity, is rendered equivalent to the Fig. 2 embodiment of the parent Specification without addition of any further electro-optic crystals by placing a mirror 14 as shown in Fig. 2 so that the light transverses the arrangement in the opposite direction and is reflected by half-silvered mirror 5 on to a photoelectric system 15. The arrangement comprises polarizer 3, #/4 plate 6 and electro-optic crystals 8 and 11 to which alternating voltages at the same amplitude but 90 degrees out of phase are applied. Mirror 14 may be replaced by a lens having a plane or concave mirror in its focal plane. The crystals 8 and 11 may comprise potassium dideuterium phosphate (KDDP). Half-silvered mirror 5 may be placed between polarizer 3 and #/4 plate 6, Fig. 1 (not shown) in which case a further #/4 plate is placed before detection system 15, the two #/4 plates being equivalent to a #/2 plate. An arrangement in the parent Specification employing (2n-1) crystals n#2 may be replaced by an arrangement including only n crystals followed by a retrodirective element e.g. a mirror. |
