Abstract: This invention comprises an electronic control system for recording, and marking hold sequences or `routes` on structures for recreational and competitive climbing and for scoring a climber's performance in ascending such routes. When used by a climber during a new route, sensitive holds electronically transmit their identifying addresses to a computerized recording system. Upon completion of the new route climbers assign a name and grade of difficulty using the computer. Climbers may also use the computer to recall routes previously designed by others. Electronically activated markers are then used to rapidly and conveniently designate the particular holds comprising the route. As the climber ascends, the holds now function to inform the computer if the climber has used an illegal hold, that is a hold which is `off route`. The system also keeps track of how high and how fast the climbers ascend, thus providing a convenient method of scoring their performance.

Abstract: In a method of high density (>10.sup.12 bits/cc) optical recording of information in a three-dimensional multilayered format, information is written in a photopolymer as submicron volume elements of altered index of refraction. The index change results from alteration of the photopolymer induced by two-photon excitation of the photo-sensitizer at the waist of a highly focused beam from a subpicosecond colliding pulse modelocked laser. Quadratic dependence of two-photon excitation on incident instantaneous intensity serves to confine crosslinking of the polymer to the focal volume; hence, bit array layers may be written with thicknesses on the order of the confocal parameter. As an example, eight well resolved bit planes can be written in a olymer film about 30 microns thick. Information written in this manner may be read with sufficient axial resolution by differential interference contrast (DIC) or confocal microscopy.

Abstract: A device for reading data stored in a high density multi-layered optical information carrier. Data which is stored in a carrier having a plurality of partially reflective data layers is read by wavefront shearing interferometry with low interlayer crosstalk. This allows data layers to be more closely spaced than previously possible thereby reducing spherical aberration and increasing the data density.