| 摘要 |
1,266,428. Holographic zone plates. INTERNATIONAL BUSINESS MACHINES CORP. June 2, 1969 [June 6, 1968], No.27723/69. Heading G2J. A holographic zone plate is made by directing coherent light 4 through a partially opaque element 3 having a plurality of relatively transparent circular windows 2, on to a photo-sensitive element, the windows being of such size in relation to the wavelength of the coherent light to scatter the light and the partial opaqueness of the element being such that the amount of light passing through the element is equal to the amount of light passing through the windows whereby a plurality of overlapping interference patterns, one from each window, is produced on the photo-sensitive element, the element then being developed and fixed. The diameters of the windows are smaller than the wavelength of the light. The light may be collimated or convergent 16, Fig.8a. The convergent beam 16 has an angle of convergence such that the non-paraxial and paraxial images are of the same sharpness. A lens may be interposed between the partially opaque element and the photo-sensitive element to reduce background brightening. The zone plate is used to generate multiple images of an object. |
