| 摘要 |
1,174,005. Optical apparatus. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. Feb.3, 1967 [Feb.4, 1966], No.5335/67. Heading G2J. An element for use in A.T.R. spectroscopy is coated with a thin film 2, Fig. 2, of low refractive index and a second film 3 of high refractive index so that a beam 10 coming through the element is partially reflected at interface R 1 , 3 as beam 22 and partially transmitted as beam 18. On reaching the interface R 3,4 . the beam 18 interacts with the sample 4 and returns as beam 20 for further splitting up at interface R 1,3 . into beams 22<SP>1</SP>, 18<SP>1</SP>, so that the initial beam has a portion forming multiple reflections in the layer 3 and thus enhancing the absorption which is characteristic of sample 4. By arranging the reflectivity of interface R 1,3 to match that at interface R 3,4 and controlling the phase of components 22<SP>1</SP> so that they are 180 degrees out of phase with component 22, by suitably dimensioning the films 2, 3, and using polarized light, substantially complete absorption can be achieved at a wavelength characteristic of sample 4. |
