Browse Prior Art Database

Moire Graphics with Pseudorandom Gratings

IP.com Disclosure Number: IPCOM000087696D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Katyl, RH: AUTHOR

Abstract

A method of obtaining contour plots using moire interference is described in an article entitled "Diffraction Patterns of Simple Apertures", by R. C. Smith and J. S. Marsh, J. of Opt. Soc. of Amer., 64 (1974) 798-803. This reference shows how to obtain interference fringes which correspond to contour lines.

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Moire Graphics with Pseudorandom Gratings

A method of obtaining contour plots using moire interference is described in an article entitled "Diffraction Patterns of Simple Apertures", by R. C. Smith and J. S. Marsh, J. of Opt. Soc. of Amer., 64 (1974) 798-803. This reference shows how to obtain interference fringes which correspond to contour lines.

By making the grid of lines plotted not a repeated set of lines of uniform width, but a repeated pseudorandom pattern, the resulting contours will take on a much sharper structure. This phenomenon is discussed in an article entitled "Moire Screens Coded with Pseudorandom Sequences", by R. H. Katyl, Appl. Opts., 11 (1972) 2275-2285, U. S. Patent 3,166,624; and U. S. Patent 3,162,711.

Moire contour graphics needs more function evaluations than does standard graphic contouring based on search algorithms. However, the basic plotting algorithm is inherently simple and contains few program steps. This type of contouring is best applied to online data acquisition systems in which the data appears as an output from a scannable detector, such as a heat sensor, light sensor, vibration pick-up, etc. In this case, no function evaluations are needed, and the moire pattern can be plotted under control of simple analog circuits or a microprocessor. The resulting contour fringes greatly aid the data analysis; many times contours (isothermal lines, for example) are the primary intent of a measurement.

Shown above is a system for obtain...