Static information storage and retrieval – Radiant energy – Color centers
Reexamination Certificate
1995-06-07
2002-11-19
Fears, Terrell W. (Department: 2824)
Static information storage and retrieval
Radiant energy
Color centers
C365S127000
Reexamination Certificate
active
06483735
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally concerns radiation, or optical, memory apparatus that use active, radiation-sensitive, memory media, and methods of using such apparatus and media.
The present invention particularly concerns (i) a three dimensional volume of that contains a number of separate, but interrelated, radiation-sensitive photochromic chemicals, (ii) the individually selective alteration, and the unique interrogation, of each of multiple photochromic chemicals that are located in the same addressable physical domains of the volume by use of intersecting beams of radiation having selected frequencies, and corresponding energies; (iii) the manner of using selected intersecting radiation beams at times upon each of several different photochromic chemicals held in a three-dimensional matrix, and the physical and/or chemical effects of such use; and (iv) the construction of binary-stated informational memory stores, three-dimensional patterns, and/or three-dimensional displays wherein a number of binary bits of information are stored in each of a great multiplicity of addressable physical spaces.
2. Description of the Prior Art
The present invention will be seen to concern the storage of multiple bits of information in the same physical spaces, preferably in the addressable domains of a three-dimensional (3-D) volume radiation memory, but permissively also in the addressable domains of a layers (of which there are typically one, but more than one such layer is possible) of a substantially planar radiation memory, typically an optical disc. In a 3-D volume radiation memory, the domains are addressed in order to be written and read by intersecting beams of radiation, typically by light and more typically by laser light.
In a four-dimensional (4-D) volume radiation memory, the domains are still addressed in order to be written and read by intersecting beams of radiation, but the beams are typically (i) quite short in time, or pulses, and are (ii) phased relative to one another. The “fourth” dimension that is referred to in the title of the present invention is thus time—as is taught in a related patent application to be a suitable basis, a “fourth dimension” so to speak, of in the addressing a three-dimensional, volume, radiation memory store. The storage of multiple bits of information in the same physical spaces in accordance with the present invention will also be seen to also be applicable to such a 4-D volume radiation memory.
The present invention will further be seen to radiatively store, and read, information that is stored in different molecules that are co-located in the same physically addressable spaces, called domains. The writing of the information into a particular type of molecule will be seen to transpire at an associated radiation frequency, or “color”. The interrogation of the written information from the same molecules will likewise seen to transpire at an appropriate radiation Frequency, or “color”. It will be seen that, commonly, but one radiation frequency is used to interrogate all the different molecules at the same time, and that each different type of molecule will produce radiation—fluorescence—of an associated frequency, or color, in response to its interrogation.
Not only are multiple bits of information is co-located as multiple colors within the same physical domains, but all the radiative writing and reading of this information will be seen to be accomplished without contamination of, or degradation to, or confusing parallel-readout of, the information that is stored (as multiple colors, and upon multiple types of molecules) in adjacent spaces. This selectivity will be seen to be realized by (i) use of the process of two-photon (2-P) absorption in judicious combination with (ii) groups of multiple selected photochromic chemicals each of which chemicals permits that it should be (i) individually uniquely radiatively selected relative to all other chemicals, while (ii) producing no radiation—particularly during fluorescence upon readout—that causes any change(s) in these other chemicals.
The present invention can therefore be considered to be a photochromic chemical system, or a radiation memory system using multiple photochromic chemicals, or as some combination of these aspects and attributes. The relevance of the prior art to the present invention is therefore best assessed not merely in snippets as may concern, for example, the storage of information as colors (e.g., photography), or the detection of information in multiple colors (e.g., spectroscopy), but as to how such prior art might contribute to any coherent scheme for the colored radiative reading and writing of information as colors within a unitary physical medium. With this consideration in mind, prior art concerning both (i) optical discs, and (ii) volume radiation (optical) memories, may usefully be regarded.
2.1 Previous Optical Discs, and Disc Systems
In optical disc storage, a focused laser beam writes bits on a spinning disc either (i) once and for all, or (ii) time and again. The tiny diameter of a diffraction-limited, focused infrared laser spot permits very high recording densities. Currently, re-writable optical disc drives use near-infrared lasers, with a 780-mm wavelength, to store up to 2 GB on each 5.25-inch disc.
Visible laser beams will do still better. With, say, a red beam emitting at 640 nm, capacities as high as 3 GB can fit on a single 5.25-inch disc, while a blue beam (415 nm) could pack about 5 GB into the same area.
An optical drive provides, in a sense, infinite storage. Extra room is easily acquired, and at modest extra cost, by simply adding media cartridges. Such abilities are welcome in modern computer applications.
In the basic optical drive configuration, the output of a semiconductor laser diode is first collimated by a lens, and is then given a cylindrical shape by a prism-like component called a circularizer. The collimated and shaped beam is then transmitted to a turning (45-degree) mirror, which reflects it onto a objective lens. The lens focuses the beam onto a diffraction-limited spot on the spinning optical disc—the equivalent of a phonograph stylus. The laser stylus is used at low power to read out recorded marks, and to ensure track-following and focusing-servo functions.
The objective lens that focuses the spot is mounted on a platform, called an actuator, which moves across the diameter of the disc. Thus the actuator gives the laser beam access to any data tack on the disc.
A prime distinction between drives is which components are mounted on the actuator. A single-head optics design has all its optics mounted on the platform. In a split optics design, however, most of the optical system is fixed to the drive chassis, with only the objective lens and turning mirror being mounted on the moving actuator. The main benefit of the latter design is that the actuator weighs less, and can thus move faster and give faster access to the data.
A more crucial distinction between systems is how they record marks. The technique which is used determines the drive's design and the type of media that can be used. In current 5.25 inch commercial systems, the marks are made in a heated medium with one of three processes: ablative (hole burning), thermo-magnetic, or phase-change. In all these techniques, the optical drivers laser is first pulsed at high power so as to heat the disc medium in preparation for recording.
In ablative recording, the focused high-power laser spot burns holes in the medium. The permanency of this way of recording data is reflected in its name: write-once, read-many (WORM) recording.
WORM recording provides the highest level of data security available in a removal device, suiting it to many applications in government, legal, and financial data archiving. In contrast, thermo-magnetic (better known as magneto-optical) and phase-change recording are re-writable processes.
In magneto-optical recording, the energy in the laser beam merely heats a spot on the disc past the disc mate
Fears Terrell W.
Fuess & Davidenas
The Regents of the University of California
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