We propose a new optical data storage system with minute spheres. To avoid a problem of jitter as instability of rotating disk speed and fluctuation of recording bit formation, we have devised a new process. The process involves the use of dye-doped minute spheres arranged upon a surface-relief structure as recording bits. Alternate laminating recordable sphere layer with sensitivity and buffer layer with insensitivity structurally limits recording bits in three dimensions. We can limit a sensitive region within a sphere diameter. A reflection-type confocal optical microscope can read out both bit signals and shape signals from minute spheres at high resolution. Confocal relection of ~10% was measured before and after recording from a single minute sphere with Spiropyran as a recording dye. Also, the shape signal from each minute sphere is utilized as a clock signal in recording and readout. The clock signal can be produced by separating a high-level signal and a low-level signal on the basis of a threshold. In our minute-sphere optical storage system, a shift between positions of the recording bit and the clock signal does not occur because the clock signal is generated based on the shape signal from a minute sphere as the recording bit. This jitter-free technique proved to be extremely effective for disk recording and readout.
We have fabricated a new optical storage media using minute spheres arranged on surface relief grating (SRG). By using minute spheres as recording bits, we can limit recordable regions by sphere size, since one mintue sphere becomes one recording bit. We can realize high resolutive reconstruction in the plane direction. We make surface relief structures on a polymer thin fim, and tried to perform diffusion arrangement and adsorptive fixation of minute spheres on it. The stability of arranged spheres was confirmed for heating and washing. Furthermore, we tried dipping method for more simple arranging minute spheres on a large area of the substrate and have made a monolayer sample of the spheres. We are able to realize high sensitive reconstruction of the media using the confocal optical system as record and readout systems. We have also succeeded in doping the recordable dyes in minute spheres.
Using the newly developed 1 kHz closed-cycle TEA CO2 laser with the efficient CO2 regenerator including the Pt/Al2O3 solid catalyst, we experimentally determined the minimum operational performance of the CO2 regenerator which is required for the stable and long-life operation of the closed-cycle TEA CO2 laser. The operational performance of the CO2 regenerator was evaluated by the fractional conversion (eta) from CO to CO2, which is defined as the ratio of the differential CO2 concentration increased by the CO2 regenerator to the total CO concentration introduced into the CO2 regenerator. The minimum eta of 0.07 was at least required to keep the laser output power at 95 percent of the initial laser output for the laser gas mixture of CO2/N2/He = 15/15/70 (percent) and at an input energy density and a clearing ratio of 150 J/l and 6.0, respectively. When operating the CO2 regenerator at eta of 0.10, no appreciable reduction of the initial laser output of 570 W due to CO2 decomposition was observed up to 1.8 x 10 exp 7 shots (5 hrs). At this time, gas analysis showed that the CO and O2 concentration in the laser gas mixture was maintained about at 0.17 percent and 0.055 percent, respectively.
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