(under the class definition) Subject matter wherein a light beam is split and caused to interfere with itself, which causes a change in the direction of the beam.
(1) Note. Diffraction bands result from interference of one part of a beam with another, as when the ray is deflected at the edge of an opaque obstacle, passed through a narrow slit, or deflected by an optical element such as a prism.
(2) Note. Diffraction usually, but not always, causes a break-up of the light into bands or a spectrum. Additionally, diffraction may also form a plurality of images from an object or merely redirect it, as in light diffractive scanners.
(3) Note. This subclass includes systems operating on diffraction from a straight edge, a circular disk or aperture, a slit or a grating; and also includes systems operating on Fraunhofer diffraction (far field wherein the incident light rays are parallel and the diffracted rays are brought to a focus by a focusing means) or on Fresnel diffraction (near field wherein the incident light rays arise from a finite source and no focusing means are used for rendering the diffracted rays parallel, or convergent).
(4) Note. Devices for producing moire fringes by shadow casting through gra-ting-like elements are excluded from this subclass.
(5) Note. All diffraction has interference but interference does not require dif-fraction.
SEE OR SEARCH THIS CLASS, SUBCLASS:
577+, for interference of light waves. 831+, for prisms.
SEE OR SEARCH CLASS
65, Glass Manufacturing,
59.1, for the process of bonding and subclass 154 for bonding glass to metal.
156, Adhesive Bonding and Miscellaneous Chemical Manufacture,
81, with melting or gasification of permanently associated solid material in situ in airtight cavity.
204, Chemistry: Electrical and Wave Energy,
192.26, for the coating, forming or etching with optical or photoactive deposition material by glow discharge sputter deposition.
264, Plastic and Nonmetallic Article Shaping and Treating: Processes,
1.1+, for optical article shaping or treating.
356, Optics: Measuring and Testing, 354, 356 for diffraction light interference, and subclass 374 for moire fringe generation by shadow casting through grating-like elements.
365, Static Information Storage and Retrieval,
124, for systems utilizing diffraction for selected masking of information.
369, Dynamic Information Storage or Retrieval,
109, with diffraction radiation beam modification.
382, Image Analysis,
210+, for pattern recognition using spatial filtering (e.g., holography).
427, Coating Processes,
164+, for transparent base optical element production and subclass 166 for vapor depositing.
428, Stock Material or Miscellaneous Articles,
167, for parallel ribs or grooves.
430, Radiation Imagery Chemistry: Pro-cess, Composition, or Product Thereof, 5, for radiation mask, subclasses 9+ for imaged product, subclass 32 for making an optical device, subclass 323 for etching, and subclass 325 for elevated pattern.
