Abstract: Methods and active media for controlled production and optical access of data in the form of physio-chemical inhomogeneities, such as controlled differences in absorption characteristics of molecules at selected regions. The methods involve use of at least two intersecting beams of radiation which are matched to selected optical properties of the active media.

Abstract: Method and active media for controlled production of physical and refractive index inhomogenetics in a volume of a suspension medium by use of at least two intersecting beams of electromagnetic radiation matched to the excited state properties of molecules in the media. In addition, complex three-dimensional physical and chemical structures are produced by selective excitation of different types of molecules in the media and by employing transportive capabilities of liquid or gaseous support medium.

Abstract: Method and active media for controlled production of physical and refractive index inhomogeneities in a volume of a suspension medium by use of at least two intersecting beams of electromagnetic radiation matched to the excited state properties of molecules in the media. In addition, complex three-dimensional physical and chemical structures are produced by selective excitation of different types of molecules in the media and by employing transportive capabilities of liquid or gaseous support medium.

Abstract: A multiple beam or "multiphoton" absorption effect is used for creating three-dimensioal sensible objects including optical elements and three-dimensional computer-type data storage and retrieval systems. The objects and systems are made according to the invention by at least two beams of optical electromagnetic radiation having a spectral characteristic matched to the excited state properties of active media molecules, wherein the beams are simultaneously or sequentially directed to a common target location to effect a desired photochemical reaction. The first beam effects excitation of the molecule of the active media at the target locations such that the coincidence of the second beam and absorption thereof by the individual molecules at the target location effects a controlled chemical reaction causing a change in physical or refractive index characteristics, or in other words, production of physical or refractive index inhomogeneities.

Abstract: Method, apparatus and product in which a three-dimensional figure is formed in situ in a medium having two active components by causing two radiation beams to intersect in the media. The dissimilar components are selected to respond to the simultaneous presence of the beams and to either react or to produce reactants which render the intersection of the beams physically sensible or distinguishable. The beams trace surface elements of the figure to be produced.