| 摘要 |
886,439. Television. TECHNICOLOUR CORPORATION. Sept. 8, 1960 [Sept. 9, 1959], No. 30827/59. Class 40(3). [Also in Group XX] In combination with means for producing at an image surface a real spatially discontinuous image consists of discrete image elements, there is provided optical diffracting means having periodic optical variation on an axis along which the said real image is discontinuous so as to produce from each pencil of light incident thereon at least two diffracted pencils of emergent light corresponding respectively to different orders of diffraction (one of which may or may not be the zero order), such diffracting means being disposed at such a distance from the image surface that at least two resultant 'images of every image element, each corresponding to at least one of the said diffracted pencils, are produced at the image surface. As shown in Fig. 2, in order to reduce the striated or grained appearance of a real image consisting of discrete small areas or lines 3 of varied area, width or brightness, a diffraction grating 2 is positioned between the image surface I and an observer, so that for each image element 3 there are produced by the diffracted rays 6 two additional virtual images 4. By altering the spacing of the grating from the image surface each image 4 may be split up into two, each of these two images corresponding to one image element. The additional image elements may be formed by a grating providing zero order, first order and second order diffracted rays or, if desired, by a blazed grating producing zero order and a single first order diffraction ray. In another form of grating the zero order is suppressed. The grating may be used in television, in which case it is mounted as shown in Fig. 1 in front of the picture tube 22. The image on the tube is produced-as two sets of parallel slightly spaced lines of two rasters, the line 9 of one raster, Fig. 8A being interleaved with the lines 10 of the other raster. The grating forms additional images at 10 from light emanating from the lines at 9 and likewise produces from the original image lines at 10 additional images at or close to the lines 9. The grating may be an amplitude or a phase grating and preferably has a pitch not greater than 1/10 of the pitch of the original image elements. In the case of an amplitude grating, the attenuation may vary abruptly from a minimum to a maximum or may vary continuously, for example, sinusoidally. |
