(under subclass 559) Subject matter wherein the optical Fourier transform spectrum is mathematically correlated with the spectrum of the spatial filter at the Fourier transform plane.
(1) Note. Included in this subclass are the so-called "matched filtering systems", wherein the Fourier transform spectrum of an object is perfectly matched or correlated to a spectrum presented at the Fourier transform plane (usually by means of a previously generated spatial filter).
(2) Note. A spatial filter is generally an emulsion mask having a transparent annular region in an otherwise opaque region used to eliminate undesired radiation that diverges
from the optical axis beyond the confines of the trans-parent region.
(3) Note. Correlation is a measure, expressed as a number between minus one and plus one between two sets of data, of the similarity of two signals.
(4) Note. Correlation is also a relationship between two variables where the strength of the linear relationship is indicated by the coefficient of correla-tion.
