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We propose a novel non-toxic method of diagnostic biomarker extraction and concentration from biofluids. The method is based on the usage of (1) magnetic nanoparticles of a few nanometres in size bearing molecular traps for biomarkers on their surface and (2) additional larger (several tens of nanometres) magnetic nanoparticles for catching smaller magnetic nanoparticles in a strong magnetic field gradient with their consequent concentration into the detection area. It is shown that the interference of an external permanent gradient magnetic field with the magnetic field of large magnetic nanoparticles allows one to catch small magnetic nanoparticles from their trajectories in a fluid at a distance around ten radii of the large nanoparticles. Theoretical analysis and mathematical simulation show the validity of the proposed non-toxic method for fast and robust biomarker extraction and concentration for increasing the sensitivity of biomarker detection. We believe that the results presented herein can serve as a starting point in the development of a new subclass of biosensors and a human body diagnostic approach with enhanced sensitivity and selectivity.

The impact of aberrations and the effect of defocusing on the efficiency of reduction of speckle noise in the system of a laser projector containing a moving diffractive optical element (DOE) is investigated. The effects of aberration and defocusing in the mechanisms of reducing speckle noise in laser projection displays were studied using the Fresnel approximation and the model of thin lenses. The results of the analysis based on the number of diffraction orders that have passed through the optical system are presented. The analysis showed that aberrations should not affect the contrast of the speckles, and the displacement of the screen relative to the image plane (defocus) only leads to re-scaling of the autocorrelation function of the scanning beam, which is equivalent to refocusing the lens to a new screen position. The use of the speckle-noise reduction method when scanning a laser display using Barker code should not require an increase in the resolution of the projection system screen compared to normal values. The resolution is determined exclusively by the requirements to image quality. It is shown that small aberrations change only the phase of the wave-front of the diffraction orders and therefore do not change the number of diffraction orders that illuminate a given area of the screen, and therefore do not change the contrast of the speckles. But larger aberrations cause a reversal of the direction of propagation of the rays that have passed through the lens. The contrast of speckles in the paraxial region of the screen is almost insensitive to aberration, but the contrast of speckles in peripheral areas changes abruptly if the aberrations change the number of diffraction orders that illuminate the area. In the optical circuit with DOE located in front of the optical modulator, the contrast of the speckles is not sensitive to the distance between the optical modulator and DOE, if the optical modulator is illuminated by all diffraction orders. Fig.: 4. Refs: 10 titles.

In this paper, we present experimental results on speckle noise suppression using a completely passive method. The passivity of the method is achieved owing to the absence of any mechanical, electr...

In this paper we present the results on speckle noise suppression in the entire visible spectrum using moving 3D diffractive optical element (DOE) based on the pseudorandom binary M-sequence. Spectral dependence of the speckle suppression efficiency as a function of moving speed and basic unit height of the DOE has been measured. The most effective 3D DOE structure for speckle reduction in the whole visible range has been determined. For the optimal DOE structure the speckle reduction coefficients of 21, 15 and 14 for light wavelengths of 633, 532 and 405 nm, respectively, have been obtained. Experimental results confirmed the high efficiency of the speckle noise suppression method in the entire visible spectrum.

The impact of aberration on the speckle suppression efficiency is investigated in a laser projector system containing a moving diffractive optical element (DOE). The results of a qualitative analysis based on the number of diffraction orders passed through the optical system are presented, along with a quantitative analysis built upon the Fresnel approximation and the thin lens model. It is shown that the speckle contrast in the paraxial area of the screen is practically insensitive to aberrations — limited to a few percent at most, due to the change in angle between diffraction orders. However, the speckle contrast in peripheral areas changes stepwise if aberrations change the number of diffraction orders that illuminate the area.

In this study, we performed a three-dimensional computational experiment on ultrashort pulse propagation in an optical fiber-tip probe that is decorated with gold nanoparticles (NPs) using a constant structure for the probe’s dielectric taper and different spatial configurations of the gold nanoparticles. Interestingly, a hot spot with the highest amplitude of the electric field was found not along the same chain of the NPs but between terminal NPs of neighboring chains of NPs at the probe’s tip (the amplitude of the electric field in the hot spots between the NPs along the same chain was of the order of 101, while that between terminal NPs of neighboring chains was of the order of 103). We eventually identified a configuration with only six terminal nanoparticles (Config4) which is characterized by the highest electric field amplitude enhancement and can provide the highest spatial resolution in the SERS interrogation of an object of interest. The ultrashort temporal responses of the hot spots for all configurations exhibited relatively high pulse elongation (relative elongation was greater than 4.3%). At the same time, due to the reflection of the incident pulse and consequent interference, the temporal responses of most hot spots contained several peaks for all configurations except for the optimum Config4. Nonetheless, the ultrashort temporal responses of all hot spots for Config4 were characterized by a single peak but with a relatively large pulse elongation (relative elongation was 234.1%). The results indicate that further examination of this new structure of a nanoparticles-coated optical fiber-tip probe with only six terminal NPs may provide attractive characteristics for its practical applications.

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.

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.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The optical memory on materials having the properties of electron trapping is a new direction at development of information storage and rewrite. Currently are pursued investigations directed on creation of a new type recording medium with the opportunity of information rewrite by optical methods as well as a medium for heteroassociative memory in optical neural systems. Primarily as such medium are used alkaline-earth metal sulphides activated by two rare-earth elements. When creating the memory on materials with electron trapping on the basis of alkaline-earth sulphides there arises a number of difficulties: (1) these materials are chemically unstable, especially they are subject to the action of water vapors; (2) films prepared by electron-beam evaporation technique have a polycrystalline structure with grain sizes in the order of 20 nm what has an essential influence on the signal-to-noise ratio at information reading. The main objective which is pursued by us consists in investigating the optical properties of new synthesized materials having the electron trapping properties which are characterized by chemical stability and are easy manufacture at preparation of amorphous structures. We have also recommended to use CaO (MgO) doped with Eu, Sm. It has known, that the optical stimulated luminescence (OSL) obtains in CaO. But OSL appears in the special prepared structures with defects. For this aim there are some methods: thermochemical reduction or radiation processing by electron beam. Besides that the OSL obtains only by nitrogen temperature (77 K).© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

One of the main storage elements is a memory element including the light-sensitive medium in which usually takes place the optical information recording. The information recording density on recording media is defined in the first place by their resolution which depends on medium homogeneity and degree of defects presence. Among new materials sensitive to light of particular interest are alkaline-earth sulphide films with additives of rare-earth element ions. Such films allow us to record information with multiple reading and rewriting. The information recording on such media takes place due to electron trapping by trap states materials irradiation with 488 nm laser radiation. The reading takes place owing to release of earlier trapped electrons from long-lived states under action of IR laser radiation (the wavelength is of 1064 nm).