Abstract: A method (and system) for guaranteeing authenticity of an object, includes providing a sample of material obtainable only by at least one of chemical and physical processes such that the sample is random and not reproducible, associating a number reproducibly to the sample by using a specific reader, and forming at least one coded version of the number, the at least one coded version being obtained by a key signature, and the version being recorded into an area of the object.

Abstract: The multiple scattering of coherent radiation in an inhomogeneous medium is used to detect attempted intrusions into a protected area or into a tamper-proof package for such purposes as preventing the unauthorized detection and copying of electronic information used for authentication and coding in electronic commerce, communications, command, and control systems. A key advantage is that any intrusion into the sensed volume will produce a detected change in the measured intensity which will be equal to the full amplitude range if the intrusion is into a cylinder with radius comparable to the wavelength of the sensing radiation. The response of the medium can also be used to provide a unique identity key.

Abstract: The optical response of high-quality epitaxial copper-oxide perovskite films on substrates such as LaGaO.sub.3 and SrTiO.sub.3 exhibits a nonbolometric component to a photoresponse at certain temperatures below the onset of the superconducting transition and when carrying bias currents of a certain magnitude. A nonbolometric superconductive photoresponsive cell and method employ such films. The photoresponsive cell and method of the invention can be used to detect electromagnetic radiation incident on the film and to switch or modulate electrical signals passing through the film.

Abstract: An atomic force microscope includes a tip mounted on a micromachined cantilever. As the tip scans a surface to be investigated, interatomic forces between the tip and the surface induce displacement of the tip. A laser beam is transmitted to and reflected from the cantilever for measuring the cantilever orientation. In a preferred embodiment the laser beam has an elliptical shape. The reflected laser beam is detected with a position-sensitive detector, preferably a bicell. The output of the bicell is provided to a computer for processing of the data for providing a topographical image of the surface with atomic resolution.