| 摘要 |
1,137,144. Polarizers. IMPERIAL CHEMICAL INDUSTRIES Ltd. April 12, 1967 [May 4, 1966], No. 19754/66. Heading G2J. [Also in Divisions B2 and G1] In apparatus for measuring the thickness of a film by measuring the absorption of infrared radiation passed through the film, the radiation is incident upon the film at an angle such that any radiation being doubly reflected by the surfaces of the film is polarized in the plane of incidence and a polarizing element is provided to remove any radiation polarized in that plane. The polarizer may be a transmission polarizer comprising two or more films of selenium or silver chloride or, where the radiation is made to pass twice through the film, a selenium reflection polarizer. |
