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# Autocorrelation Function Generator

IP.com Disclosure Number: IPCOM000097917D
Original Publication Date: 1961-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 37K

IBM

## Related People

Horwitz, LP: AUTHOR

## Abstract

The autocorrelation function D(x', y') of an input pattern f(x, y) is defined as: D(x', y') = Sigma(x,y) * f(x, y) * f(x+x', y+y') where f(x+x', y+y') represents the input pattern shifted by an amount x', y'.

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Autocorrelation Function Generator

The autocorrelation function

D(x', y') of an input pattern f(x, y) is defined as: D(x', y') = Sigma(x,y) * f(x, y) * f(x+x', y+y') where f(x+x', y+y') represents the input pattern shifted by an amount x', y'.

This expression is simulated optically by superimposing the shifted pattern on the unshifted pattern and measuring the areas that are common to both patterns.

Light source 1 is directed through beam splitter 2 to input pattern transparency 3. The light pattern passing through 3 is then directed by beam splitter 4 and mirrors 5, 6 and 7 to the photocathode 8 of a beam tube 9. The luminescent pattern 10, thus generated on the screen of 9, is directed by 4, 3 and 2 to a light sensitive element 11. Tube 9 contains a deflection system 12 which permits pattern 10 to be shifted in position. The light impinging on 11 for any given displacement x',y' of 10 represents an element of the autocorrelation function. The entire function may be serially generated by shifting pattern 10 through all displacements x',y'. Alternatively, any selected sequence of x',y' displacements may be used.

No light from source 1 is directed toward the element 11. Various techniques are used to block any of this light which might be reflected by elements of the optical system. A polarizer may be placed between source 1 and splitter 2 and a second properly-oriented polarizer may be placed between splitter 2 and 11. An alternative to this uses a monochromatic...