OPTICAL DECONVOLUTION OF SEISMI RECORDS

摘要

1,215,620. Spatial Filtering. PAN AMERICAN PETROLEUM CORP. Dec.20, 1968 [Dec.27, 1967], No.60818/68. Heading G2J. [Also in Division C4 and H4] Unwanted time dimension in formation is processed out of seismic data by superimposing a Fouvier transform of the time dimension of data from a transparency and containing as a varying intensity of illumination the frequency spectrum of each trace of the data on an image of the respective trace position in the transparency, these being located in the transform plane a transparent film that progressively acquires density by being exposed to illumination in said transform and acts as a filter, while passing illumination to form a modified image. The image is produced a plurality of times for different densities until the desired modified image is achieved. A monochromatic light beam 11 illumates a transparency 15 of side-by-side variable density seismic wave traces. The transmitted and diffracted light passes a cylindrical lens, with its cylindrical axis parallel to the said time dimensions, which lens forms a transform at 17a of the distance dimensions only. A lens 18 forms the fourier tranform of the time dimension at 20a superimposed upon the film 20. Lenses 22, 24, 26 set up a modified image 28. The film 20 is one in which greater intensities of illumination produce greater densities. Preferably the film is exposed and developed and them reexposed and developed until the required density is achieved. Alternatively the film, which may be a photographic film, may be immersed in a bath of developer and continuously exposed and developed. In a suitable embodiment the transparent film comprises a cell formed from optically flat plates containing for example a photochromic material such as spiropyraus dissolved in an alcohol or liquid hydrocarbon solvent, or an electrolyte, the insides of the glasses plates having a transparent conducting film such as cadmium sulphate selenide. In order that at least part of the illumination representing zero frequency in the frequency spectrum in transform plane 20a is transmitted a vertical glass fibre is vertically located along the D.C. line of the cell, or a wire is located along that line on the mounting plate.