Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Patent
1995-08-23
1997-10-21
Ben, Loha
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
369100, 3692752, 369 4437, G11B 700
Patent
active
056803869
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an optical system and method for writing/reading information on a recording medium. It also relates to a recording medium.
The principles of optical storage which are being developed at the present time employ semiconductor lasers operating in the near IR (.lambda..apprxeq.0.8 .mu.m), in order typically to obtain storage densities of the order of 10.sup.8 bits cm.sup.-2. These orders of magnitude correspond to the writing of elementary bits of the order of 0.8 .mu.m in diameter on a read-only disc, or a magneto-optical writable and erasable medium. The object of the invention is to obtain a significant improvement in the storage capacity. It is possible to increase the storage capacity by increasing the information density per unit of surface area of the recording medium. It is also possible to increase this capacity by recording into the thickness of the recording medium.
The embodiment principles and means forming the subject of the invention are fully compatible with the optical structure of read heads for optical discs and digital optical memories.
The invention thus relates to an optical method of writing/reading information on a recording medium, characterized in that the writing of information is achieved by use of a write beam including the superposition of at least a first optical beam at a first wavelength (.lambda.) and at least a second optical beam at a second wavelength (.lambda./2) which is less than the first wavelength.
The invention also relates to an optical system for writing/reading information for a recording medium, characterized in that it includes an optical source emitting a beam at a first wavelength, and a frequency changer receiving this beam and transmitting, to the recording medium, a write beam comprising a first beam at a first wavelength and a second beam at a second wavelength less than the first wavelength.
Finally, the invention relates to an optical recording medium, characterized in that it includes a non-linear material exhibiting a recording threshold such that it records an information item by the use of a first beam of a first wavelength in a part only of the illuminated area, the information being recorded in such a way that it can be read only by a second beam of a second wavelength less than the first wavelength.
The method of the invention allows recording/reading on a preformatted medium on which the preformatting information has a resolution corresponding to a read beam at the first wavelength.
It thus includes the following steps: at a low power level (of the order of a few mW, or less than one mW); low-power level; the two beams at high-power level, or of one of the two beams; reading the data information.
The invention also relates to a method characterized in that the blocking of the first beam is done in a blocking time which can be greater than 10 ms.
The various subjects and characteristics of the invention will emerge more clearly in the description which will follow, and in the attached figures which represent:
FIG. 1, a general example of embodiment of the method and of the system according to the invention;
FIGS. 2a and 2b, a diagram explaining the recording according to the invention;
FIG. 3, a more detailed example of the system according to the invention;
FIGS. 4, 5a and 5b, examples of frequency doublers according to the invention;
FIGS. 6a, 6b, 7a and 7b, an example embodiment of a filtering device usable in the system of FIG. 3;
FIG. 8, a variant embodiment of the system of FIG. 3;
FIG. 9, a system making it possible to focus the two wavelengths contained in the recording beam at the same point;
FIG. 10, a system making it possible to record into the thickness of the recording medium;
FIGS. 11 and 12, systems making it possible to set c/ the power of the source;
FIGS. 13a, 13b, energy diagrams explaining the method and the system according to the invention;
FIGS. 14, 15a, 15b, examples of preformatted recording media usable in the context of the invention.
According to a general method of recording/reading, a recordi
REFERENCES:
patent: 3909608 (1975-09-01), Le Merer et al.
patent: 3912922 (1975-10-01), Lacotte et al.
patent: 3945790 (1976-03-01), Puech
patent: 4020278 (1977-04-01), Carre et al.
patent: 4024513 (1977-05-01), Huignard et al.
patent: 4037251 (1977-07-01), Bricot et al.
patent: 4038524 (1977-07-01), Puech et al.
patent: 4039764 (1977-08-01), Bricot et al.
patent: 4052706 (1977-10-01), Spitz et al.
patent: 4068258 (1978-01-01), Bied-Charreton et al.
patent: 4142208 (1979-02-01), Oprandi et al.
patent: 4157931 (1979-06-01), Bricot et al.
patent: 4176277 (1979-11-01), Bricot
patent: 4199783 (1980-04-01), Huignard et al.
patent: 4387452 (1983-06-01), Bricot et al.
patent: 4405862 (1983-09-01), Bricot et al.
patent: 4449785 (1984-05-01), Huignard et al.
patent: 4551733 (1985-11-01), Cornet
patent: 4868804 (1989-09-01), Carvenec et al.
patent: 4888266 (1989-12-01), Lacotte et al.
patent: 5258969 (1993-11-01), Refregier et al.
patent: 5319481 (1994-06-01), Fergason
patent: 5323372 (1994-06-01), Puech et al.
Huignard Jean-Pierre
Le Carvennec Fran.cedilla.ois
Loiseaux Brigitte
Puech Claude
"Thomson-CSF"
Ben Loha
LandOfFree
Optical method and system for writing/reading information on a r does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical method and system for writing/reading information on a r, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical method and system for writing/reading information on a r will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1012634