An augmented reality display based on a planar waveguide made in photo-thermo-refractive glass had been demonstrated. The monolithic integration of multiplexed volume Bragg gratings with the ...waveguide platform provided in/out-coupling and image transmission from a portable projector. Design and calculation of the grating configuration was performed. The optical replication method was simulated and implemented for manufacturing the multiplexed coupling elements. Resulted field of view was limited by the projection system of the prototype, however can be expanded beyond 50 o .
The phase distortions arise due to the atmospheric turbulence, the experimental conditions or a low quality of the imaging system. They can seriously limit the resolution of the image. Phase ...distortions can be spatially dependent, which means that a linear space-invariant transfer function cannot completely correct all phase errors in the field of view. Computer holography can be used to access a complex-valued optical field from an object under coherent illumination after detecting interference of intensity between the object and the reference beams. In this work, we developed approaches to improve image sharpness to measure phase distortions in computer holography using the example of defocus measurement. Image enhancement algorithms use a nonlinear optimization procedure to determine and measure phase distortions to form a reconstructed image at a high resolution. Our work was focused on numerical modelling, developing algorithms and conducting laboratory experiment.
The recording process of multiplex Bragg diffraction gratings for lightguide displays by the method of optical copying with use of a phase mask is described. In this experiment, the lightguides are ...made of photothermorefractive glass. A photoresistive relief phase diffraction grating unattached to the light guide plate is used as a phase mask. A compact augmented reality display is created on the basis of studying the angular multiplexing of such Bragg gratings.
Erwinia amylovora causes a quarantine disease called fire blight that affects most plants from the Rosaceae family. An efficient and rapid disease diagnosis tool is needed to prevent the spread of ...the pathogen. The main objective of this study was to develop a lateral flow immunoassay (LFIA) to detect E. amylovora and compare different organs of plants for optimization of LFIA testing. A total of 11 strains of E. amylovora and related species were tested for specificity of the developed LFIA. The detection limit of E. amylovora was equal to 4 × 105 CFU mL−1 in plant extracts. LFIA showed high specificity and did not demonstrate positive results with non-related species. Meanwhile, LFIA's effectiveness was confirmed through testing artificially infected leaf samples of apple, pear, and black raspberry. Reliable results were obtained 10 min after the start of LFIA for all testing strains. Different plant organs (121 samples) comprising apple, pear, hawthorn, quince, blackthorn, and cherry from naturally infected areas with symptoms of varying severity were tested. The LFIA was performed using samples from leaves, twigs, flowers, fruitlets, and bacterial ooze; for confirmation commercial kits based on fluorescent amplification–based specific hybridization PCR were used. Using several samples from one plant (cluster) significantly increased the accuracy of infected plant detection, the overlap of LFIA and PCR were equal to 70.2% for individual samples and 93.5% for clusters. Observed recovery of E. amylovora for different organs differed by up to 20%. We found out that using vascular tissues was better than using leaf extracts. This result demonstrates that LFIA's effectiveness improved when more appropriate samples were used.
•An on-site lateral flow immunoassay (LFIA) was developed for Erwinia amylovora.•We found out that vascular tissues was better than using leaf extracts.•The observed recovery using vascular tissues compared to leaves differed up to 20%.•The developed LFIA was performed using variety of plant species under Rosaceae.
A method is proposed for reducing the detection limit of enzyme-linked immunosorbent assay (ELISA) of potato virus X, based on the multiple introduction of tyramine into immune complexes and the ...subsequent detection of an enzyme label. During ELISA, a step by step formation of sandwich complex containing immobilized antibodies – potato virus X – horseradish peroxidase conjugate with antibodies to the virus was carried out. Peroxidase catalyzed the multiple insertion of a tyramine-biotin label into protein molecules, providing signal amplification upon the addition of the streptavidin-polyperoxidase conjugate. The conditions of the assay that ensure a high degree of amplification and a minimum background signal were established. The use of tyramine amplification made it possible to lower the detection limit by more than 30 times (from 100 to 3 ng/ml) when assayed in the buffer and extracts of potato leaves, slightly increasing its duration. Tyramine amplification is based on the use of universal reagents and can be used to reduce the detection limit of ELISA for other antigens.
Linear displacement encoders are necessary in field of machine tools, metrology and electronic industry. Those devices provide nanometric resolution when constructed according to the interferometric ...scheme. Mathematical modeling of signal transfer process into its optical system to analyze an interference field is described. Signal intensity depending on a small displacement of moving grating phase shift correlations is considered. A sample model of the linear optical encoder is developed based on the optical scheme under research.
A novel rapid (20 min) fluorescent lateral flow test for chloramphenicol (CAP) detection in milk was developed. The chosen format is a binding-inhibition assay. Water-soluble quantum dots with an ...emission peak at 625 nm were applied as a label. Milk samples were diluted by 20 % with phosphate buffer to eliminate the matrix effect. The result of the assay could be seen by eye under UV light excitation or registered by a portable power-dependent photometer. The limit of CAP detection by the second approach is 0.2 ng/mL, and the limit of quantitation is 0.3 ng/mL.
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Principle of proposed immunoassay of chloramphenicol using quantum dots
In this paper, dependencies of the angular and spectral selectivity on the incidence angle of the reference beam in a scheme for obtaining reflection and transmission holograms are obtained and ...analyzed. It is shown that for obtaining color holographic stereograms a scheme for obtaining transmission holograms is more suitable. While the angular selectivity of reflection and transmission color holograms is the same, the spectral selectivity of the reflection hologram is much higher at all wavelengths of recording. A method and equipment for one-step digital recording of color full-parallax holographic stereograms with rasterless image are developed. Samples of color full-parallax security holographic stereograms with a “flip-flop” effect in the image were obtained. The quality of the reconstructed image verifies high spectral selectivity for this type of holograms.
Thromboembolism of pulmonary artery is life-threatening condition due to acute right ventricle failure and cardiogenic shock. System thrombolysis is the main way of reperfusion in massive pulmonary ...embolism with a very high risk of fatal hemorrhage complications. There is a popular revascularization method in two last decades such as endovascular treatment. It allows to recover the blood flow into occluded pulmonary arteries up to three weeks after confirmed embolism episode and to decrease major bleeding risks. Now trials corroborate the high efficacy and safety of interventional treatment the usage of which would allow to improve prognosis in massive pulmonary embolism.
Combined holographic optical elements for optical systems of multicolor character/symbol display devices are described. This element combines the functions of four-level diffractive optical elements ...with high diffraction efficiency and spectral plasmon filters with a variable bandwidth depending on the incidence angle. The theoretical studies suggest the feasibility of combining the two types of elements in a single structure.
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