Effect of Microindentation on Electroluminescence of SiC P-I-N Junctions

The influence of microindentation on the electroluminescence of silicon carbide was studied in forward-biased 4H SiC p-i-n junctions. Four spectral regions at approximately 390, 420, 445 and 500 nm initially observed on virgin samples strongly depend, in regard to magnitude, on the condition of the starting die. These spectral regions may be interpreted as arising from either phonon-assisted band-to-band transitions or from defect-related transitions. The same SiC die were then subjected to mechanical damage brought about by a series of closely spaced microindentations directed approximately perpendicular to the c-axis. The spectra taken after a first set and subsequently a second set of microindentations are distinct from the initial spectra in all cases, and differences are interpreted as being due to the modification of existing defects or additional defects being generated mechanically. The influence of microindentation on the ideality factor is measured and discussed. Measured light flux with respect to a standard light source is also shown at each microindentation stage.

Restoration of Hardware Function of Spectral Colorimeters Using Regularization Methods

The problem of determining the spectral characteristic of a controlled sample under conditions of limited a priori information using regularization methods is considered in the paper. A change in the state of the surface of optical elements significantly increases the light scattering, so it is necessary regularly to take into account the amount of scattered light in the light flux reflected from the surface and the measured and comparative samples. The conversion of the light flux into the electrical signal of the photodetector can also occur non-linearly. This requires the development of such measurement method that considers both the scattered light and various non-linearities of the measuring circuit. It is known that the mathematical model of measurement is described by the Fredholm integral equation of the first kind, its solution under the accepted assumptions is recommended to be sought in the form of a matrix equation using a recurring procedure. With regard to the fact that the estimation of the initial data errors in the equation is associated with certain difficulties, in the case under consideration, it is advisable to determine the regularization parameter based on the method of quasi-optimality. A characteristic disadvantage of the known analytical and experimental methods for determining the hardware function of a spectral device is that they do not take into account its change during operation. Since the actual hardware function of the device usually differs from the Gaussian curve, the use of hardware functions in the form of analytical dependencies does not always give the desired result, and for experimental methods, special equipment with a quasi-monochromatic radiation source is required. An algorithm for restoring the hardware function of a spectral device based on regular methods for solving ill-posed problems is proposed. The estimation of the matrix operator of the hardware function is proposed to be obtained on the basis of explicit least squares estimation algorithms. The expediency of choosing a value of the regularization parameter that minimizes the accepted characteristic of the accuracy of the solution is indicated.

Limits to Ionization-parameter Mapping as a Diagnostic of Hii Region Optical Depth

We employ ionization-parameter mapping (IPM) to infer the optical depth of H ii regions in the northern half of M33. We construct [O iii]λ5007/[O ii]λ3727 and [O iii]λ5007/[S ii]λ6724 ratio maps from narrowband images continuum-subtracted in this way, from which we classify the H ii regions by optical depth to ionizing radiation, based on their ionization structure. This method works relatively well in the low-metallicity regime, 12 + log ( O / H ) ≤ 8.4 , where [O iii]λ λ4959, 5007 is strong. However, at higher metallicities, the method breaks down due to the strong dependence of the [O iii]λ λ4959, 5007 emission lines on the nebular temperature. Thus, although O++ may be present in metal-rich H ii regions, these commonly used emission lines do not serve as a useful indicator of its presence, and hence the O ionization state. In addition, IPM as a diagnostic of optical depth is limited by spatial resolution. We also report a region of highly excited [O iii] extending over an area ∼1 kpc across and [O iii]λ5007 luminosity of 4.9 ± 1.5 × 1038 erg s−1, which is several times higher than the ionizing budget of any potential sources in this portion of the galaxy. Finally, this work introduces a new method for continuum subtraction of narrowband images based on the dispersion of pixels around the mode of the diffuse-light flux distribution. In addition to M33, we demonstrate the method on C iii]λ1909 imaging of Haro 11, ESO 338-IG004, and Mrk 71.

On the use of light sensors on CubeSat nanosatellites

The paper focuses on the usage of the TCS34725 light sensor in the motion control system of the SamSat-Science nanosatellite platform. The sensor is designed to determine the angle between the sensor normal and the direction to the light emitter center. We developed a technique for calibrating light sensors, carried out a series of experiments, verified the nominal characteristic of the light sensor, and found the dependency of mean squared deviation (MSD) of the sensor values on the angle of incidence of the light flux. Three layouts of light sensors on the lateral faces of the nanosatellite are considered: on a plane; on the faces of a quadrangular pyramid with an inclination angle of 45°; on the faces of a truncated quadrangular pyramid with an angle of inclination of 45°. We have chosen a circuit that provides measurements with minimum noise.

Spectral analysis of the photoconductivity for characterization of CdTe И CdZnTe detectors

The results of the application of optical methods are considered: spectral analysis of photoconductivity in the range 400–1800 nm and field measurements of stationar photoconductivity to study the bulk and surface characteristics of CdTe and CdZnTe gamma-ray detectors. The studies of the photoresponse of the samples were carried out in different irradiation modes: modulated at a frequency of 25 Hz and a constant light flux. The measurements were carried out at room temperature on domestic and foreign materials of detector quality. Using the spectral photoconductivity method, the parameters of deep levels, which affect the detector properties, have been estimated in the studied materials. Based on the calculations of the field dependences of the photoconductivity, the volume and surface parameters of the capture and recombination of non-equilibrium carriers in the investigated detectors were determined. The results of calculating the transport characteristics of charge transfer by electrons μτe in detectors are compared with similar parameters measured using the traditional method of irradiating the detector with alpha particles. To measure the band gap in CdTe and CdZnTe at room temperature the method was modified for calculating ΔEg. The possibility of monitoring the Zn content in CdZnTe detectors using the spectral photoconductivity method is shown.

Application of technical vision systems for diagnosing the quality of cattle feed

Russian and foreign literature on the development of diagnostic systems and scanning of objects using a vision system with deep machine learning programs has been analyzed during the study. The features of the technological process of feeding cattle have been studied. A system of non-contact assessment of the dry matter content/humidity of the components of the feed mixture of natural cultivation on the example of a corn silo using technical vision systems was proposed. A database of images of corn silage was collected and the dependences on the intensity of the reflecting light flux of the silage were revealed taking into account changes in humidity. The research was conducted in 2020 on the basis of the Federal Scientific Agroengineering Center VIM (FNAC VIM), using experimental equipment of the Institute of General Physics of the Russian Academy of Sciences named after A. M. Prokhorov and FNAC VIM. A stand with a technical vision system has been developed that allows to classify the components of a cattle feed mixture by color characteristics. The obtained dependences of the reflecting intensity of corn silage allow us to assert the prospect of using a vision system for express-evaluation of the quality indicators of feed mixture components. Taking into account the level of robotization of technological processes of feeding cattle, the problem of assessing the quality indicators (in particular, the dry matter/moisture content) of the components of a feed mixture is relevant.

The Use of a Dynamic Cooling Mechanism for a Double Faced Photovoltaic Power System

The use of solar energy systems among renewable energy sources is gaining importance day by day. Photovoltaic systems have a special importance among solar energy systems. Although the incident light flux increases the electrical energy produced in the solar panels, the increase in temperature caused by the radiation reduces the efficiency of the solar panels. Important methods are being studied in order to increase this falling efficiency. Dynamic cooling systems are one of the important methods used in this field. In this study, a dynamic cooling mechanism was designed and developed for a double-faced photovoltaic power generation system. From this point, it was concluded that temperature is one of the important factors affecting the efficiency of solar panels.

The relationship of the parameters of the optical density of the sample and the absorbance of the sample material

The relationship of the parameters of the optical density of the sample and the absorbance of the sample material is studied, which is relevant for the analysis and differentiation of measurement results by devices with light flux filtration and spectral devices (densitometers and spectrophotometers). To identify the analytical dependence of the obtained values of the optical density of the sample and the absorbance of the sample material, a formula is derived for calculating the diffuse optical transmittance density if the detected radiation contains directional and diffuse components. The first term in the obtained formula characterizes the absorbance of the sample material, the second is a correction due to the diffuse component of the radiation, and is a function of the ratio of the diffuse and regular transmittances. Expressions are obtained that allow functional and quantitative determination of the relationship of the absorbance of the sample material and the parameters of the optical transmittance density of the sample. The results of calculating the absorbance of the sample material, the component of diffuse radiation, diffuse optical transmittance density and corrections of these values are presented.

Prior Compensation Algorithm for Cerenkov Luminescence Tomography From Single-View Measurements

Cerenkov luminescence tomography (CLT) has attracted much attention because of the wide clinically-used probes and three-dimensional (3D) quantification ability. However, due to the serious morbidity of 3D optical imaging, the reconstructed images of CLT are not appreciable, especially when single-view measurements are used. Single-view CLT improves the efficiency of data acquisition. It is much consistent with the actual imaging environment of using commercial imaging system, but bringing the problem that the reconstructed results will be closer to the animal surface on the side where the single-view image is collected. To avoid this problem to the greatest extent possible, we proposed a prior compensation algorithm for CLT reconstruction based on depth calibration strategy. This method takes full account of the fact that the attenuation of light in the tissue will depend heavily on the depth of the light source as well as the distance between the light source and the detection plane. Based on this consideration, a depth calibration matrix was designed to calibrate the attenuation between the surface light flux and the density of the internal light source. The feature of the algorithm was that the depth calibration matrix directly acts on the system matrix of CLT reconstruction, rather than modifying the regularization penalty items. The validity and effectiveness of the proposed algorithm were evaluated with a numerical simulation and a mouse-based experiment, whose results illustrated that it located the radiation sources accurately by using single-view measurements.

Opimization of the main design and operating parameters of the micronization device

The article substantiates the main characteristics of the studied device of micronization in the processing of grain feed by the method of micronization. Here, an experimental micronizer that micronizes feed grain was taken as the object of research. A multi-factor experiment was also conducted to determine the optimal distance of the infrared lamp from the quartz glass and the optimal power of the light flux. The experiments were carried out on an experimental installation equipped with a “Legrand” dimmer, which allowed changing the radiation power of the lamps. For the experiments, a symmetrical Box-Bench plan was selected from a rotatable, composite second tier. The studies were conducted on wheat, barley and velamir.