The improved scheme of data recording process on an optical disc based on a substrate made of high-stable materials has been proposed. Information layer with depth of 115nm and width of 600nm has been obtained on sapphire substrate by ion-beam etching using improved scheme. These experimental results allow to create the sapphire optical discs for long-term data storage.
The non-homogeneous multilayer medium was proposed for laser thermal recording. The mathematical model of laser thermal recording based on the phase transition of non-homogeneous medium (such as melting, ablation, evaporation) to simulate and optimize was developed. It was shown that in multilayer recording medium can be performed narrower structures than in monolayer films on similar conditions. It was shown that for getting small structures the thermoconduction of recording medium should be much smaller than the thermoconduction of substrate on which a medium is deposited. It was demonstrated that in the case of strong light absorption in recording layer its thermal conductivity must be sufficiently large to ensure the transfer of heat on a distance that equals to the thickness of the layer during a time interval equals to the difference in time for warming up to the phase transition temperature of the central part of the light spots and area that separated from a center of light spot on a distance equals to the thickness of layer.
One of the major concerns in the area of high efficient solar cell production is a substantial shift between the solar radiation spectra and optical absorption spectra of a photoelectric transducer that significantly reduces solar cell efficiency. We propose a concept which based on coating of conventional and cheap photoelectric transducer with a luminophor that transmits longer wavelengths of the sunlight, absorbs shorter wavelengths and converts them into longer ones by the value of the Stocks shift. While photoluminescent light is not collimated and thus losses may reach up to 50% of converted light, it was also proposed to make micropattern formation at photoelectric transducer surface. We propose synthesizing of specific materials based on composite pyrazoline dyes with addition of polymethylmethacrylate, polystyrene and UV-laquers. It was revealed that synthesized luminophor coating are characterized by sufficiently enough Stocks shift (200-400 nm), high quantum yield (near 80%) and stability under circumstances of long term radiation. Further research demonstrated potential of the significant characteristic’s improvement by introducing of organic dye molecules in the white zeolite matrix with additional laser annealing at low intensity. Experimental results have shown that photoluminescent spectrum of pyrazoline dye didn’t change shape, bandwidth and amplitude for last 10 years. It was decided that obtained stability is being caused by porous matrix of white zeolite. Simulation of the solar cell functioning helped to understand physics of the process and simplify problem of microrelief and luminophor optimal parameters search.
The method of high-density data recording by laser thermo-lithography with ion-beam etching was proposed. The
nanocomposite films were created by the spin-coating method on basis of organic positive photoresist and added
synthesized dyes characterized by absorption in the spectral region 390-410 nm and which are able to be evaporated by
405 nm laser radiation. The pits with 250 – 300 nm width were performed on the thin organic nanocomposite films by
405 nm laser beam focused by 0.85 NA lens. The organic nanocomposite film with obtained pits was used as a mask for
reactive ion-beam etching of glass substrate. The 150 nm pits were performed on the substrate surface in the result of the
laser thermo-lithography with ion-beam etching.
Results of numerical simulation of near-field optical data storage using microstrip probe are presented. Simulation is
carried out on the basis of the finite-difference time-domain method. Features of the information reading process from
the ROM and RW (based on the phase transmissions of Ge2Sb2Te5 film) formats of optical discs under illumination and
illumination-collection mode are analyzed and considered. Mathematical modeling has shown that the signal from the
ROM-format disc under illumination mode, despite the fact that the probe has a significant far-field transmission
coefficient, has a large crosstalk and small spatial resolution (significantly worse than a size of probe aperture). Unlike
illumination mode, signal under illumination-collection mode (pure near-field method) has a resolution close to the size
of the aperture, good amplitude and contrast, as well as relatively low crosstalk. However, information reading under
illumination-collection mode from RW-format disc is not able to get the same good quality signal. Therefore the further
optimization of the method is required to improve the signal quality of RW format.
Results of implementation of technical solution for long term data storage technology on the basis of single crystal
sapphire are presented. The effect of birefringence on the distribution of the focused laser beam through a uniaxial
birefringent medium having a vertical orientation of the optical axis is analyzed. An expression for the calculation of the
geometric aberrations of the focused laser beam in single-crystal substrate of the optical disc has been presented. It is
shown that the problem of data reading through a substrate of negative single crystal sapphire can be solved by using for
reading a special optical system with a plate of positive single crystal materials. The experimental results confirm the
efficiency of the proposed technical solution.
Microprism diagnostic set KK-42 for ophthalmology application comprises 42 separate microprism elements - strabismus optical compensators and it is designed for the image displacement at vision diagnostics.
The main requirement for optical compensators is high quality of observed images. However, strong diffraction
phenomena and chromatic aberrations due to light dispersion exist for microprisms similar to any other prismatic
systems. Structure simulation was carried out to minimize the acuity degradation and to avoid observed image
discretization. The simplest method to diminish aberrations is the application of filters and colour plastics. Experiments
and calculations were performed which showed the opportunity to diminish twice the chromatism zone by filters to the
value of 20-25 angular minutes.
Another method of decreasing chromatic aberrations is application of additional prism microrelief - saw tooth
diffractive optical element. In optical compensators the first microrelief with the pitch of 600-800 μm serves as a
refractive prism. Diffractive element with the pitch of 15-20 μm operating in first diffractive order is optimized in such a
way that dispersion of the first diffractive order compensates dispersion of the compensator. This method allows to
compensate dispersion totally at any spectrum zone.
Optical discs are widely used for storage of archival data represented in a digital form. Long-term storage of information
recorded on standard CDs is provided by periodical rewriting (once in 3-5 years) on the new carriers. High-stable lightsensitive
materials and special reflective metal coatings are proposed to use for increasing the information storage terms
of the optical discs. The conducted researches have showed that the application of vitreous chalcogenide semiconductors
in optical WORM discs assures the data storage terms up to 30 years. Substantially larger terms of data storage can be
realized on the optical ROM carriers. Attainment of the guaranteed data storage terms within several hundreds years is
provided in such carriers by applying high-stable materials substrates and information should be represented in the form
of a micro-relief structure on the substrate surface. Sapphire, quartz, silicon, glass-ceramics and other materials can be
utilized for manufacturing substrates of optical BD discs (and other subsequent high-density disc formats). These materials
allow creating substrates characterized with increased melting temperature, chemical and mechanical resistance.
Furthermore, using the mentioned materials for substrates production permits applying high temperature materials, such
as chrome and nickel, to creation of high-stable refractive layers and demonstrating the sufficient mechanical adhesion
between the refractive layer and the substrate. Modern methods of thermo-lithography offers creating of nano-size images
on photo-resist layer deposited on the substrates. Those images can be transformed to the nano-size relief structures
on the surface of the high-stable materials substrates by techniques of reactive ion-beam etching.
In present report the methods of the identification marks creation on the surface which are intended for the determination of licensability of CD production are considered. The main attention is devoted to the methods of the identification marks recording on master disks during the process of CD fabrication.
Results of researches of processes for forming visually observable identification elements on CD substrates are given. The opportunity of forming identification elements in an area of information block recording without data distortion is shown. The results of experimental researches on recording holographic identification elements on CD substrates are presented.
The results of experimental and theoretical investigations aimed at applying non-organic photoresists for mastering optoelectronic devices are represented. Samples for investigations were prepared using thermal evaporation of the glass with different As-S-Se compositions in vacuum onto a glass substrate. When exposing photoresist to obtain interference 2D/3D patterns, we used He-Cd laser irradiation with the wavelength 440 nm. The exposure was chosen from 20 to 150 mJ/cm2, and spatial frequencies of obtained gratings were from 600 to 3600 mm-1. The resist samples were processed using a waterless organic selective etchant based on amines. Results of investigations showed that As40S60-xSex (x=0-20) photoresist is characterized by higher holographic sensitivity (i.e. energetic expose necessary for providing given value of the diffraction efficiency). This enables us to create various combined optical-digital protective elements and master-copies for all types of optical disks (CD, DVD).
KEYWORDS: Near field optics, Near field, Microscopes, Near field scanning optical microscopy, Waveguides, Magnetism, Absorption, Optical microscopes, Transmission electron microscopy, Dielectrics
A near-field optical microscope on the basis of two trapeziform metallic strips on the surface of a dielectric cone is investigated1. It is shown that such construction of a near-field probe significantly improved the optical efficiency of a near-field microscope.
The field distribution in the vicinity of probe apex is investigated for this probe and for the usual SNOM probe. On the basis of mathematical simulation it was shown that this type of a near-field microscope is promising for use in optical information recording with pit length less than 200 nm and also for using as optical heating element in magnetic information recording. The construction of a near field microscope for information recording is proposed on the basis of this near-field microscope and a solid immersion lens2.
The model of a near field strips probe with cleaved apex is proposed. A method of checking the distance between a probe and the surface on the basis of exciting mechanical vibration of cleaved apex by voltage step is offered. The oscillation amplitude and their attenuation are determined by measuring high-frequency electromagnetic oscillation, which are excited by oscillation of opposite charges at the apex of a probe.
The investigation was carried out on the basis of a mathematical model and an experiment is needed for full investigation.
The types of distortions present in audio signals reproduced from Edison phonograph cylinders are considered and classified. An effective approach and algorithm for processing of obtained audio information is proposed. It is shown that the use of a sound signal with frequency range up to 20 KHz at processing has two obvious advantages. The first one allowed to retain the highest harmonics of a sound signal which are not perceived directly by ear, but have a positive influence on the formation of a common sound picture. The second one - in this signal it is more convenient to remove pulse interference (clicks, crackling), since the pulse fronts are steeper and the probability of their detection is increased.
The present work contains results of the investigations of the master disks manufacturing process and the following stamp plating process for compact disk duplication. The salient feature of the process under consideration is the use in a master disks as a photosensitive material of the vacuum deposited organic dye layer, the relief image on which is formed directly in the irradiation-recording process. In the work are considered the master disks manufacturing process. An organic dye is deposited by the thermal vacuum evaporation method. This provides the thickness test of a coating directly during the manufacturing process, the high purity of a photosensitive layer and its very high uniformity in thickness.
A computer model has been developed to calculate the optical properties (reflection and absorption coefficient) for various dye thicknesses between 20 and 300 nm for situation various reflecting layer Au or Al (Si). For a high k dye to power absorption being very critically dependent on dye thicknesses. In the less absorbing dye the situation be more extreme, with oscillatory interference effects causing considerable variations in absorption (reflection) from a maximum to a minimum every 50 - 70 nm (Au) and 100 - 120 nm (Al), and 150 nm (Si). A series of calculations are presented on a number of different layer structures and materials in an attempt to optimize the storage medium.
Production of high quality master discs used in CD manufacturing process is possible only at light-sensitive material exposure process optic control carrying out and relief image production. High precision of relief image production process control on the master disc surface is provided in case of relief formation in the process of data recording. The results of optical discs mastering using direct reading technology (recording quality control) in the process of recording are considered below. The high- sensitive material composition selection effect upon pit form is given. The conditions in which the light-sensitive layer material is practically completely removed from master disc surface are defined. The after-record direct reading method comparison to the method of image production using photoresists is given.
Photoluminescent spectra of CaO, MgO oxides, doped with rare-earth ions have been studied. The stimulated by IR- light photoluminescence in these materials has discovered at room temperature for the first time. Optically stimulated luminescence in Ca(Mg)O: Eu, Sm for different concentrations of dopants after exposure to UV-radiation ((lambda) equals 250 nm) and radiation with (lambda) equals 488 nm has been investigated. The physical model to explain luminescence and stimulated luminescence mechanism is proposed. Materials on the base of alkaline-earth oxides activated by rare-earth ions are suitable for multiple rewrite of information.
The description of a method for optomechanical sound reproduction from Edison cylinders the distinctive feature of which is recording the surface profile of the cylinder sound track with its subsequent conversion into sound by means of a computer is presented. With the purpose of decreasing the destructive influence of reproduction system on the cylinder surface the recording the surface profile of a sound track is carried out at rotational speed smaller by a factor of 20 - 30 of that one at which was executed the information recording on it. The realization of a proposed method allowed to reproduce information recorded on cylinders with minimal action and to obtain a high quality of a reproduced signal.
To overcome the limitation of the current memories some authors developed method for storing data throughout a volume of memory material using two-photon absorption effect. In this work we represent the three-dimensional vector analysis of diffraction laser beam by the simple model of this volume data storage. We represent the volume data storage as homogeneous dielectric in which three- dimensional grating of spheres with complex (epsilon) , (mu) are located. To evaluate scattering field of partial wave we used Lorenz-Mie theory. The total scattering field is sum of partial scattering fields and some small addition field of re-radiation. The addition field of re-radiation was evaluated in first approach of perturbation theory. The investigation results were used for the determination of recording information limits into the memory material.
Three-dimensional vector diffraction analysis for optical disc systems is described. The geometrical form of information pits and tracts is simplified to rectangular form. The disc surface and side wall of pits are perfect conductive. We considered two physical model of the pits: (1) in the bottom of pits the partial waves of rectangular waveguide satisfy impedance condition; (2) bottom of pits are connected to semi-infinite dielectric space. In the first case we obtained two-dimensional integral equation for electrical field in upper end of pit. In the second case we obtained two integral equation for upper and lower pit ends. The diffraction of laser beam by information pits was regarded in Fourier optics approach. We use the most exact theory of diffracted vector field to evaluate Fourier transform function for Gaussian beam. This approach gave us possibility to investigate the diffraction fields in the case of the lens with big aperture and small linear size. The obtained mathematical algorithm was applied then to the study of diffraction linear polarized Gaussian laser beam by disc information surface and to the diffraction laser beam by small rectangular aperture in infinite shield. The digital results showed that to obtain accuracy for integral characteristic of fields less than one percent it is necessary to take eight Fourier members for every coordinate on every pit end.
The changes in optical properties of thin films of vitreous chalcogenide semiconductors in the pro cess of long-duration storage are studied. The feature of films composition influence and their preparation on the long-duration process are established.
At present there exist many methods of preparing film structures on an inner surface of cylindrical elements by vacuum technology. They are designed for evaporation of metallic, oxide and other surface layers mainly and cannot practically be used for the formation of optical layers using multi-component, strong dissociative materials. Therefore we have developed the flash evaporation method using fiber as a film-forming material. This method allows us to obtain defect-free, x-ray amorphous, uniform over the thickness recording layers from multi-component strong dissociative materials.
Reversible recording medium based on glass/crystalline phase transition was considered. The spatial/temporal distribution of the crystalline phase in radiation zone was studied. Methods of dynamic range expansion while recording and providing of high signal/noise ratio after multiple recording/erasing cycles were considered.
For measurements of reflection factor of recording cover, deposited on internal surface of glass cylindrical tube, we designed and manufactured a stand. It permits us to conduct the measurement of reflection factor of recording cover of optical information carrier within a time of not more than 25 s. The measurement of reflection factor is conducted on an 0.83 mkm wavelength of semi-conductor infrared laser. We admit the measurement of reflection factor for samples on flat substrates.
The process of optical recording on ablation mechanism carriers shows a peculiar microrelief. The peculiarity of the latter is in the presence of an annular rim around the pit, of the carrier material arising by action of surface tension. This force on the liquid phase of microregion was subjected to the thermal action of a laser beam. During reading for increasing the signal- to-noise ratio, it is necessary to achieve optimal relations for parameters of reading laser beam, and geometrical pit dimensions surrounded by the annular rim. The method of scalar theory of diffraction did not allow to investigate the influence of geometrical sizes rims of pits on scattering characteristics of the laser beam from pits. In this connection, the mathematical simulation problem of the informaiton reading process from the surface with such form of units is of current concern.
As an alternative to recording media on the tellurium base, recording media built in the form of matrix structures in which a photo(thermo)active component is included into the matrix can be used. We suppose that the most effective preparation method of such media which provides the deposition on substrates of any form can be a dissociation method of organometallic compounds (OMC). Depending on the choice of OMC, atmosphere in which occurs its decomposition, additions and conditions of process following there can be obtained by polymerization of OMC ligands in which is distributed a metal phase (metal-polymeric media) and an oxide matrix in which are implanted organic ligands changing its parameters. The gradient metal spreading was created by increasing the pulse amplitude of voltage discharge from 500 to 2000 V. The content of metal was increased in direction from substrate and was near substrate 0 - 10 at percent and near free film surface up to 80 at percent. The film composition was investigated by means of the layer-to-layer auger analysis using microscope JAMP-10 S. The comparative analysis of Raman spectra of starting OMCs and prepared from them films showed the advent of new bonds of the type metal-metal, carbon-carbon and the decrease of bonds quantity of the type carbon-carbon, metal-ligand. The action of focused laser radiation on such films leads to formation of microholes in the center of the irradiation region and on peripheral areas it leads to an additional OMC decomposition.
The results of technical determination analysis are given; this analysis had been used while creating mass memory on optical cylinders. The distinctive features of accumulators on the cylinder carriers are considered.
The results of the experimental investigation of the interaction process of focused laser radiation with metal-polymer films with uniform and gradient metal spreading are presented. A model construction of this process and focused laser radiation diffraction on pits are discussed.
KEYWORDS: Crystals, Laser crystals, Numerical simulations, Chalcogenides, Mathematical modeling, Interfaces, Information operations, Pulsed laser operation, Semiconductors, Signal to noise ratio
The thermal crystallization process dynamics in a reversible recording medium on the base of chalcogenide semiconductors was studied by means of numerical simulation. The Kolmogorov-Avraami equation was used for nonisothermal crystallization process simulation. The spatial-temporal distribution of crystalline phase in the writing area was obtained. The writing modes under which a uniform distribution of crystalline phase in the irradiated area is achieved were investigated.
The results of the process of irreversible optical bit-by-bit recording on metal-polymeric films obtained by the method of plasma metal organic chemical vapor deposition are presented. The dependence between conditions of producing recording media and their properties has been established. The comparison of recording process on metal-polymeric antimony recording media with data recording on tellurium alloy films has been carried out.
Thin films, in which weak chemical bonds of dopands break by laser irradiation during the information recording process, causing d-metal atoms restoration and optic contrast phase educing, are developed.
The properties of metal-polymeric recording media obtained by the decomposition of alkyl tin (Sn) and antimony (Sb) compounds in low-temperature plasma have been investigated. We have experimentally determined the changes of pit shapes during the photothermal recording and the basic medium characteristics when changing the metal and carbon concentrations in the films.
The authors propose a method to increase the information recording density in optical storage by means of optical immersion. The influences of parameters of information carrier substrate and moving immersion liquid flow on the aberrations of information recording-reading optical channel are investigated. It has been shown that in the case of optical immersion data recording the most acceptable information carrier was a carrier shaped as an optical cylinder. The information recording in such an optical cylinder is performed on its internal surface. The recording media and the method of depositing these media on the cylinder's internal surface are analyzed. The technical characteristics for the immersion type optical storage are given.
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