| 摘要 |
1278659 Colour projection: diffraction gratings AGFA-GEVAERT A G 4 June 1969 [4 June 1968] 28352/69 Heading G2J In the photographic recording of a colour image of an object on a black-and-white photo-sensitive layer, an image of the object is projected on to the layer by an objective and also images of colour selective filters 4b-4e located in the objective plane are projected as diffraction gratings, e.g. 5, 6, 7, on to the said layer by a lenticular screen 3, the filters 4b-4e being of different widths and/or relative angular positions and having different grid constants and/or azimuth angles for the different colours. As the grids are thus related to orders of diffraction reproduction of the coloured image from the black-and-white layer is achieved by illuminating the layer with reference to the desired orders of diffraction. The filter strips 4b-4e of desired widths to give a continuous series of bands are located between the two halves 1a; 1b of the objective. An area 4a on the optic axis corresponding to the zero diffraction order has no filter. Immediately adjacent this area are yellow filters 4b, and moving outwards from the centre on either side respectively red, blue and green filters 4c-4e. They are so arranged that no gaps appear between the areas covered by individual lenslets of lenticular screen 3. If desired the strips may be angled to one another, e.g. green 17, Fig.3, and blue 18 of same width but at right angles, and red 19 at 45‹ to these two but wider by a factor #2. The two outer strips 4e are each of such width that the image of one of them formed on the layer by one lens of the screen 3 coincides with the image of the other of the outer strips 4e. If the lenticular screen 3 is cylindrical the transmission factor of these strips 4e is half that of the other strips. Alternatively the images of strips 4e may abut. The screen may also comprise spherical lenses. The reproduction of coloured images is as described in Specification 1267861. In an alternative embodiment there is formed on the layer superimposed black-and-white images of a plurality of objects. In this embodiment the colour-selective filter is replaced by a slit the width and/or azimuthal angle of which is arranged to be adjusted between successive exposures, or is arranged to be replaced by another slit of different width and/or azimuthal angle between successive exposures. |
