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Kinoform Filter

IP.com Disclosure Number: IPCOM000074123D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Patau, JC: AUTHOR

Abstract

Kinoform optical filters are desirable since they are operative in incoherent light. However, simple kinoform filters are limited to positive filter operators. For certain applications such as the optical processing of seismic traces both positive and negative operators are required. For many seismic filtering operations, a kinoform filter can be made with only positive coefficients having the Fourier-domain response which best approximates (in the least squares sense) the desired Fourier domain response. These filters have good high spatial frequency behavior, but permit leakage of undesired low spatial-frequencies.

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Kinoform Filter

Kinoform optical filters are desirable since they are operative in incoherent light. However, simple kinoform filters are limited to positive filter operators. For certain applications such as the optical processing of seismic traces both positive and negative operators are required. For many seismic filtering operations, a kinoform filter can be made with only positive coefficients having the Fourier- domain response which best approximates (in the least squares sense) the desired Fourier domain response. These filters have good high spatial frequency behavior, but permit leakage of undesired low spatial-frequencies.

An optical filtering system for optically filtering seismic data employing a single kinoform filter is provided by placing a kinoform filter having the required best positive operator in the optical path of a conventional office copier employing a reusable photoconductor. Due to the "edge effect" phenomena which results in large black areas being represented by only their edges upon reproduction, the office copier acts as a highpass filter. This provides a rough or approximate filtering system which compensates for the low spatial-frequency leakage of the kinoform filter.

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