Optical Radiation Sources Research Articles

Optical signal filtering method in three-component laser doppler anemometers

Methods for filtering signals in three-component laser Doppler anemometers for separating signals in optical paths of complementary devices are considered. A method is proposed for suppressing the mutual influence of signals based on the use of monochromatic sources of optical radiation with close wavelengths and bandpass optical filters. The possibility of implementing the proposed method of signals optical filtering in three-component laser Doppler anemometers using modern semiconductor laser diodes and bandpass optical filters is shown.

Experimental researches of dynamic spectral processing of optical radiation in the active electro-optical system

The process of dynamic spectral processing of optical radiation in the active electro-optical system that provides enhancement of the contrast of the image target has been experimentally researched. A routine of experiment and a diagram of an experimental setup have been developed. The sources of optical radiation in the transmitting part of the active electro-optical system were three semiconductor lasers operating in the ranges of the red, green, and blue spectral regions. Absorption optical filters were used in the experiment as the elements simulating the spectral properties of the reflecting surfaces of the target and the background. To enhance the contrast of the target image, the spectral composition of the laser radiation is formed to provide maximum suppression of the background signal with minimum attenuation of the optical signal of the object. When forming the spectral density of the laser radiation intensity, a priori information about the spectral characteristics of the target and the background has been used. The results obtained in the course of the experiment confirm the possibility to separate the target signal from the background interferences due to using the dynamic spectral processing of optical radiation in the active electro-optical system.

Пожарная опасность светодиодных осветительных систем в условиях обитаемых гермоотсеков космических летательных аппаратов

Представлены результаты оценки пожарной опасности светодиодных осветительных систем в условиях обитаемых гермоотсеков космических летательных аппаратов (КЛА). Проведен анализ этих систем с учетом влияния обогащения атмосферы кислородом, а также особенностей их конструкционного исполнения. Показана перспектива пожаробезопасного использования светодиодных осветительных систем для освещения и сигнализации в условиях обитаемых гермоотсеков КЛА и даны рекомендации по обеспечению пожарной безопасности светодиодных осветительных систем. When operating the habitable hermetic compartments of spacecrafts there is a need for high-quality illumination of the hermetic compartment for astronauts’ activities. It is also required to use light sources to indicate the operating modes of the equipment. Previously occurring fire-hazardous situations in the habitable hermetic compartments of manned spacecrafts caused the need to put fire hazard of these products among the main hazards of space flight. Currently, LEDs, which are semiconductor elements, are widely used as sources of optical radiation. They began to be used in space engineering not only as lamps, but also for other purposes. LED lamps have a significant advantage over all alternative options. They have longer service life, high lamp efficiency, reduced heat generation, high vibration resistance, low weight. At the same time, in LED lighting systems there are used highly flammable polymer materials, in particular polypropylene, which is one of the most flammable polymer materials in the air environment. In the oxygen-rich atmosphere of hermetic compartments the fire risk in any electrical equipment increases due to a significant decrease of the self-ignition temperature and the ignition energy of polymer materials with the oxygen concentration increase in the atmosphere. The paper analyzes fire hazard of LED lighting systems used as illumination in the command compartment of a manned transport space vehicle (MTSV). The analysis was carried out taking into account the influence of oxygen enrichment of the atmosphere, as well as taking into account the design features of LED lighting systems for use in the habitable hermetic compartments of spacecrafts. The analysis of the lamp showed that solid and liquid polymeric materials are the only combustible substances in their design.

Investigation of explosion-proof fiber-optic pressure sensors using the method of additional loss control

The results of the study of explosion-proof fiber-optic pressure sensors using the method of monitoring additional losses, carried out within the framework of the grant project of the Ministry of Education and Science of the Republic of Kazakhstan AP09562222. Experiments have been conducted on the use of various sources of optical radiation for its use in fiber-optic pressure sensors. The dependence of the strain values is determined, which is represented by a mathematical model with various types of approximation.

ANALYSIS OF TEMPERATURE-QUALITY REHABILITATION OF MODERN ROAD IMPROVEMENTS IN poultry house

Modern technologies of feeding and keeping farm birds are based on keeping them in a special room. The content of birds in cages is explained by the fact that the manufacturer uses every cubic meter of useful space contained in it as efficiently as possible. Industrial poultry farming, as the most knowledge-intensive and dynamic branch of the agro-industrial complex, makes a significant contribution to providing the population of developed countries with food. The intensification of the process of keeping birds suggests the maximum use of the volume of these premises. For this reason, birds are placed in high-density cell batteries. In such conditions, birds practically do not get fresh air and sunlight. In this regard, the physiological state and productivity of the bird depends on the parameters of the indoor air environment. Therefore, there are such scientific and practical tasks as the development of technical means based on resonant power systems and modern optical radiation sources. In this regard, the scientific justification of energy-resource-protective lighting and irradiation equipment for poultry farming is also very relevant.

Sources of optical radiation based on ZnTe/ZnSe/ZnS heterostructures

The heterostructures of zinc chalcogenides β-ZnTe/ZnSe/ZnS were obtained by isovalent substitution. The regimes for obtaining materials that ensured the stability of the cubic lattice of heterolayers of zinc chalcogenides β-ZnSe and β-ZnS were determined. The isovalent elements Se and S determined the solid-phase substitution and determined the formation of heterolayers in the lattice of the surface of the base crystal. The optical transmission, reflection, and photoluminescence spectra of the heterolayers are studied. The analysis of the results of studies of the energy structure of the obtained heterolayers was carried out, which indicates the correspondence of these heterolayers to the compounds of zinc selenide and zinc sulfide obtained by classical technological processes. They are also confirmed by the results of studies of the optical transmission of β-ZnSe and β-ZnS films specially obtained on transparent substrates under the same growing conditions as compared to isovalent substitution.

Frequency-tunable transient Cherenkov radiation from an inhomogeneous medium

We propose a scheme to generate coherent radiation with a tunable frequency spectrum based on the excitation of an inhomogeneous thin layer of a resonant medium by an ultrashort pulse. The Cherenkov-type radiation emitted in a transient stage, i.e., while the excitation wavefront is still propagating over the medium, is shown to contain additional frequency components, which are determined by the spatial frequency components of the medium's density distribution and the excitation geometry. We demonstrate that the spectral content of this transient radiation can be adjusted in wide limits by controlling the spatial density distribution of the resonant medium and the shape of the excitation wavefront. Our theoretical results pave the way towards simple and compact swept-frequency or frequency-tunable optical oscillators as well as sources of the frequency-modulated optical radiation.

OPTOELECTRONIC DEVICE FOR MEASURING THE POWER OF LASER RADIATION

A device for measuring the power of the laser radiation.has been designed. The device consists of transmitter and receiving part. The transmitter includes optical radiation source and optical system for collimation of radiation. The receiver part consists of silicon photodiodes, electronic signal processing unit and unit for measurements.

Digital Lighting Technologies to Control Galleria Mellonella Behavior

The authors found out that the greater wax moth (Galleria mellonella) harmed bee colonies by destroying up to 30 percent of honey in a beehive. They studied the results of experiments on controlling its behavior using a developed automated microprocessor system that maintained optical radiation sources duration.(Research purpose) To develop light technologies using a microprocessor-based automated system that allows controlling Galleria mellonella behavior by realizing attractive optical radiation characteristics.(Materials and methods) Galleria mellonella behavior was controlled by an automated system that the authors worked out for maintaining the required duration of the experiment and optical radiation parameters. The ATmega328 microcontroller was chosen as the main element of the developed microprocessor automated system. The authors created a program for it using visual programming FLProg version 5.3.0.(Results and discussion) The authors found that, regardless of the experiment duration, Galleria mellonella butterflies prefered radiation with 400 nanometers wavelength.(Conclusions) The authors determined that radiation with 400 nanometers wavelength and 10 minutes duration was attractive. They showed the ability to control Galleria mellonella behavior, luring butterflies to a specific place in the beehive with comfortable spectrum parameters. An automated system for controlling the greater wax moth butterfly behavior was developed on ATmega328 microcontroller by implementing attractive optical radiation characteristics.

Recent Advances in Terahertz Photonic Technologies Based on Graphene and Their Applications

Graphene is a unique 2D material that has been extensively investigated due to its extraordinary photonic, electronic, thermal, and mechanical properties. Excited plasmons along its surface and other unique features are expected to play an important role in many emerging photonic technologies with drastically improved and tunable functionalities. This review is focused on presenting several recently introduced photonic phenomena based on graphene, beyond its usual linear response, such as nonlinear, active, topological, and nonreciprocal effects. The physical mechanisms and various envisioned photonic applications corresponding to these novel intriguing functionalities are also reported. The presented graphene‐based technologies promise to revolutionize the field of photonics at the relatively unexplored terahertz (THz) frequency range. They are envisioned to lead to the design of compact harmonic generators, low‐power wave mixers, linear and nonlinear sensors, magnet‐free isolators and circulators, photonic topological insulators, modulators, compact coherent optical radiation sources, and subwavelength imaging devices.

The Influence Of Semiconductor Leds On The Aquatic Environment And The Problems Of Developing Lighting Devices For Fish Industry Based On Them

The paper presents the results of an experimental study of the influence of semiconductor LEDs on the aqueous environment. It has been shown that the use of semiconductor LEDs in fish farming is the preferred source of optical radiation in the development of microorganisms in natural or open bodies of water, in particular, in the growth of functional systems as aquatic plants, fish and their larvae, as well as moderate development of zooplankton, phytoplankton, detritus, which are the natural feed base of fish and their larvae.

Revisiting the nature of dark sunspots: the sun as a heat engine

This work is a continuation of the author's studies,1,2,3 related to the elucidation of the physical nature of dark sunspots. They showed that the appearance of cold sunspots, the temperature of which is below the temperature of the photosphere, is incompatible with the second law of thermodynamics. Sunspots in the Sun's photosphere can only be hot. This article provides a thermodynamic analysis of the work of the Sun as a heat engine. It is shown that sunspots are dissipative structures that spontaneously appear in the photosphere of the Sun and ensure its viability as a source of optical radiation. Sunspots play the role of a cooler for the sun's global heat engine, and without them its radiant glow would be impossible, just like the operation of any heat engine without a cold heat sink. In addition, it is shown that all the phenomena of solar activity are caused by the operation of the photospheric heat engine of the Sun, in which sunspots are the source of heat.

The optical sensor for detecting NO2 and O3 using a white GaN LED

This article describes the scheme and principle of operation of an optical sensor for detecting nitrogen dioxide (NO2) and ozone (O3) based on the effect of optical absorption spectroscopy. A distinctive design feature of the proposed technical solution is that it is proposed to use an inexpensive powerful white led based on GaN as an optical radiation source, which has two relatively wide radiation peaks at wavelengths λ from 420 to 440 nm and λ from 525 to 650 nm. To separate the light streams and form separate measurement channels, three multilayer optical coatings were synthesized: a broadband beam-splitting coating and two narrow-band reflective coatings.

Mathematical models of sunlight for dynamic lighting systems of agricultural objects

A promising method for illuminating agricultural objects is dynamic lighting with a change in the luminous flux and correlated color temperature of artificial optical radiation sources adapted to the natural dynamics of sunlight. The purpose of this study is to develop mathematical models of changes in illumination on the control surface and correlated color temperature of natural solar radiation during the day. The experimental method established a linear relationship between the correlated color temperature of sunlight and the surface illumination in the direction of the Sun. The regularity of time changes in the height of the Sun above the horizon was determined. The functional dependence of illumination on the height of the Sun above the horizon was revealed. The equations can be used to control artificial light sources in the systems of dynamic illumination of agricultural objects in order to increase the productivity of animals.

Перетворювач інформаційного сигналу в опір для системи автоматичного контролю

Potentiometric sensors are widely used in the construction of automatic and automated process control systems. In potentiometric sensors, resistance is the output signal and is values depend on the magnitude of the input signal. As the input signal, voltage, current, digital code, angle of rotation, displacement or other signal is usually used. In practice, the task of simulating of the signal which is coming from the built-in potentiometric sensor is often appeared. An additional potentiometric sensor can be used to simulate the signal of the built-in sensor, which allows to set the required resistance value by changing any external parameter. The principle of constructing an information signal-to-resistance converter which allows to simulate the potentiometric sensor of the state of the system which is controlled is considered in this article. Two photoresistors are used to make an information signal to resistance converter, which are selected with similar parameters and set so that they are optically connected to the optical radiation source, and the illumination on the sensitive areas of the photoresistors was almost the same varying in proportion to the change in the brightness of the optical radiation source. In this case, the values of the resistances of both photoresistors will be almost the same at any values ​​of the brightness of the optical radiation source. A calculator that measures the resistance value of the second photoresistor, compares it with the required resisstance value and sends a signal to the control device of an optical element with a remotely variable transmittance, which, influencing the luminous flux, synchronously changes the illuminance of the sensitive areas of both photoresistors, thus changing their resistance is used in this circuit. The change is occurring till the equality between the measured value of the resistance of the second photoresistor and the specified value. And since the resistances of both photoresistors change synchronously, the resistance of the photoresistor, measured by the consumer of information, will correspond to the required value.

Creating a biophysical trapping device based on an optical radiation source with a light-emitting diode

The article addresses the problems of using semiconductor LEDs in the creation of environmentally friendly, high-efficiency, energy-efficient biophysical trapping device and their introduction into agriculture. The use of semiconductor LED lamps that are compatible with the spectrum of solar light in the device is preferred over other methods in that it is effective in combating pest flying insects and does not harm beneficial insects. The proposed device is environmentally friendly compared to chemical and biological methods of pest control. The device consists of an energy-saving circuit, which does not require high energy in use. This prevents inconveniences when used in field conditions, and the efficiency of useful work in the fight against flying insects is higher than other methods.

Matrix of Photosensitive Elements for Determining the Coordinates of the Source of Optical Radiation

Matrix of Photosensitive Elements for Determining the Coordinates of the Source of Optical Radiation

Space Object Detection Algorithm Leveraging Absolute Photo-Detector Calibration

This paper introduces a new space object detection algorithm that is designed to process image data taken from astronomical telescopes for the purposes of finding sources of optical radiation in space. Specifically, the algorithm is designed to find unresolvable space objects or objects that possess an angular size that is too small to appear as anything, but a point source as viewed through the telescope conducting the search. The proposed approach involves calibrating the image data into units of photoelectrons and then executing an estimation algorithm to compute the strength of the hypothetical sources in the image. A Likelihood Ratio Test (LRT) is then implemented to make a determination if the hypothetical sources are classified as space objects or not. The proposed algorithm is demonstrated to achieve a higher probability of detecting unresolvable objects than the matched filter, which is still the state-of-the-art approach for finding optical sources in astronomical images. The new approach involves a pre-processing step where the amplitude of the optical source in a given test location is estimated under the hypothesis that at optical source exists at that location. The median filter is used to estimate the background level in the vicinity of the test location. Once these parameters are estimated, A likelihood ratio test is used to determine whether an object is present at the test location. The new algorithm is tested against the matched filter detector using two sets of measured short exposure data of the star Polaris and two stars in its vicinity taken with a small telescope. Receiver Operating Characteristic (ROC) curves are produced for the two detection schemes showing that the new algorithm out-performs the old one with a difference of 10 percent in the probability of detection, which is demonstrated to be statistically significant in these experiments with confidence as high as 90%.

Method for correction of experimental action spectrum using actual overlapping spectra of radiation sources

Experimental dependency of the photosystem's response on the wavelength of exciting radiation, also known as action spectrum, may be substantially affected by the spectrum shape of this radiation. This is especially important in the case, when different radiation sources are used for the investigation of action spectrum. For instance, too wide emission peaks of radiation sources can blur the scopes of actual action spectrum and distort information about the properties of photosystem at certain wavelength regions. Here, we propose a method for the correction of experimental action spectrum by the recalculation of experimental data of photoresponse according to actual spectra of exciting radiation. In the case of overlapping radiation spectra from different radiation sources, this method results in much better correlation of experimental action spectrum to actual action spectrum or absorption spectrum of photosystem. The data on photoactivity of several photocatalysts are presented to illustrate and validate the proposed method.•Activity of photosystem depends on the actual spectrum of the radiation source•Single-peak optical radiation sources with the same basic wavelength may cause a different photoactivity•Effect of actual spectrum of the light source on the photoactivity is to be considered

On the Photoresponse Kinetics and Amplitude of Silicon Photoelectric Multipliers

Abstract—The influence of the supply voltage and temperature on the characteristics of the photoresponse of silicon photoelectric multipliers has not been adequately studied. In this study, the influence of these factors on the time characteristics of the photoresponse of silicon photoelectric multipliers is investigated. A block diagram of the experimental system is presented. In the system, the optical radiation source is a light-emitting diode, and photoresponse recording is provided by a specialized hardware–software complex. The results of studies of the effect of the supply voltage and temperature on the photoresponse kinetics and amplitude of silicon photoelectric multipliers, fabricated on the basis of n+–n–p+- and p+–p–n+ structures, upon pulsed optical excitation at a wavelength of 630 nm are reported. It is established that, upon the exposure of silicon photoelectric multipliers to optical pulses identical in duration, wavelength, and energy at the same temperature and overvoltage, the photoresponse duration is longer for silicon photoelectric multipliers based on the p+–p–n+ structure. It is found that the photoresponse rise time is associated with the photocurrent amplification coefficient and the photosignal pulse relaxation time is associated with the series resistance of silicon photoelectric multipliers. The photoresponse rise time is longer for silicon photoelectric multipliers with a larger photocurrent-amplification coefficient. A longer photoresponse decay time is inherent in silicon photoelectric multipliers with higher series resistance.