Alexandre Michtchenko

Thermal Deformation Analysis of Vibrated‐Type Optical Fibers Sensors

In this paper we analyzed and calculated the deformation based on noon symmetrical temperature distributions in the cross section of optical fiber. Deformation distortion causes the micro vibrations of the optical fibers under periodical thermal excitation applied to one side of cylindrical surface. Calculations were made to optimize the exposure and to minimize energy, needed for realization of this class of sensors based on vibrations.

Optical Diagnostics Fungal and Virus Diseases of Plants

Potential opportunities of the Laser Analysis of a Microstructure (LAM) of tissue for diagnostics of defeat of plants are investigated by viral and mushroom diseases. In comparison with methods of fluorescence of a chlorophyll and enzyme-linked immunosorbent assay a new way (LAM) at early stages of pathogenesis differs significantly greater sensitivity.

Modification of the germination and the total length of wheat seedling by an infrared-continuous wave semiconductor laser

The present work analyses the stimulation effects caused by a continuous wave semiconductor laser in the infrared spectra on wheat seeds. Infrared radiation is supposed to produce higher effects that red radiation. In this work we investigated if the infrared laser radiation could modify the growth of wheat seeds. To stimulate the wheat seeds fifteen laser treatments were used. The germination and the total length of wheat seedlings were analyzed. The highest effects were obtained for an intensity of laser radiation of I=60 mW/cm2 and exposition times of 30s and 60s. The intensity of laser radiation and the exposition time are importan parameters that can improve the germination and the growth of wheat seedlings.

Laser diagnostics of fruits in storage

The parameters of induced chlorophyll fluorescence can reveal the post-harvest effect of internal and external factors on various apple and pear fruits being used as example. Dynamic index determining drop rate of fluorescence intensity in slow induction phase is considered to be the most sensitive one. The given methods allow high precise diagnostics of fruit functional state for optimization of storage period and terms.

Analysis of deformation for optical fibers vibrated-type sensors

We analyzed and calculated the deformation based on non symmetrical temperature distributions in the cross section of optical fiber. Deformation distortion causes the micro vibrations of the optical fibers under periodical thermal excitation applied to one side of cylindrical surface. Calculations were made to optimize the exposure and to minimize energy, needed for realization of this class of sensors based on vibrations. The same effect can play negative role for the fiber-optic communications systems. The main feature in presented work from the similar theoretical considerations is the analysis of the non-symmetrical heating azimuthally with appropriate deformations

Photobiostimulation Effects Caused for Low Level Laser Radiation with λ = 650 nm in the Growth Stimulus of Biological Systems

This paper has as principal objective to determine the value of some parameters of light that are determinants in the activation or inhibition of the growth stimulus in a biological system. In this case intensity and dose, as important parameters, were considered. Semiconductor and GaAlAs lasers with lambda=650 nm were used to irradiate the biological systems. In the first part of this study three different biological systems were defined. In the fist biological system Triticum aestivum L (wheat) seeds were used; for the second biological system Cucumis sativus L (cucumber) seeds were used, and finally for the third biological system human fibroblasts were used. The responses of the three biological systems were analyzed using statistical processes when intensity and dose were varied. The results obtained indicate that when the appropriate light parameters are used activation or inhibition can occur

Reconstruction of Refractive Index Profile of Optical Fibers by Near Field Technique

The knowledge of optical fibers refractive index profile allows to get the propagation characteristics in telecommunication systems as well as some parameters that are essential as: core diameter, cladding characteristics, attenuation, and base band. The near field technique is based in the fact the light that emerge in certain point into optical fibers core is proportional to difference between the refractive index profile and the cladding in that point

Far Field Technique Applied in Single Mode Optical Fibers for Studying of Modal Field Diameter

The far field technique is used for measuring the mode field diameter into single mode optical fibers. This is a main characteristic involved for detecting loss. The mode field diameter is an irradiance power distribution expression per unit area through fiber-end face. For a power distribution Gaussian into single mode optical fibers the mode field diameter in which the electric field and magnetic field are reduced. The technique far field allows to measure the irradiance in a fiber-end face. The far field power distribution describes the emitted power per unit area in the far field region. The far-field region is the region far from the fiber-end face. The mode field diameter is affected by blending loss, join loss, splicing loss, dispersion wave guides, as well as devices involved in optical link (regenerators, amplifiers, multiplex, etc.)

The family of chemical fiber-optical sensors for remote control of admixtures in gases and liquids

The main subject of presented work is the development of the family of fiber-optic chemical sensors for admixtures detection in air or in water. The experimental results are presented in details for the sensors for NH3, H2S and RSH with the appropriate models for operation in gas and liquid media. These sensors could be used for remote control of the common pollutions in environment, or for the measurements of the admixtures in different processes in industry. The production of these sensors for the detection and measurement of the concentrations of toxic gases yields rather simple and inexpensive tools for laboratory and industrial use.

The deformation analysis of optical fibers for vibrated-type sensors

In this paper we analyzed and calculated the deformation based on noon symmetrical temperature distributions in the cross section of optical fiber. Deformation distortion causes the micro vibrations of the optical fibers under periodical thermal excitation applied to one side of cylindrical surface. Calculations were made to optimize the exposure and to minimize energy, needed for realization of this class of sensors based on vibrations. The same effect can play negative role for the fiber-optic communications systems. The main feature in presented work from the similar theoretical considerations is the analysis of the non-symmetrical heating azimuthally with appropriate deformations.