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The description of the National primary standard for the unit of average laser radiation power GET 28-2016 with a power range from 10–9 to 5·10–3 W is described. The principle of operation of a standard based on a photoelectric trap detector in the range from 10–9 to 5·10–3 W is described. As a result of metrological studies at National primary standard, it was determined that the value of the total standard uncertainty of reproduction and transmission of an average power unit for the range from 10–9 to 5·10–3 W is no more than 0.36 %. The model and theoretical characteristics of the measuring beam splitter, allowing to expand the range of the National primary standard to the range of kilowatt power levels, are presented. National primary standard allows solving the problems of metrological support of promising low-level laser ranging systems both in the ground and in the aerospace field, ensuring the uniformity of measurements of radiometric parameters of low-intensity laser radiation fluxes.

A method of attenuating high-power laser radiation using a small metal diffraction grating as an attenuator for power measurement was analyzed. The thermal operating modes of the attenuator were investigated, and various systems of cooling were considered. Errors of the coefficient of attenuation that are associated with the polarization and spectral composition of the radiation, and by the radiation absorption, mechanical deformation, and temperature mode of the diffraction grating are estimated. It is shown that a small metal diffraction grating can be used as a calibrated attenuator of powerful laser radiation with wavelength 1.06 μm. The relative error of the attenuator was 0.64%.

The paper presents calculations of the amount of effort and the reliability of the method of brute-force attack on a cipher using a statistical criterion for plaintexts, which has type 1 and type 2 errors. Calculated values of parameters of the discussed cryptanalysis methods for a cipher allows better predictions of its remaining safe operational life taking into account statistical characteristics for recognizing the plaintext and changes in the communication channel parameters.

Parameters of pulsed electric discharges arising between insulated metal parts of helicopter rotor blades, which generate electromagnetic interferences for onboard radio stations operating in the very short wave (VSW) and ultrashort wave (USW) bands have been studied. These discharges appear as a result of the in-flight engine-driven differential charging of helicopters. In-flight and laboratory experiments were used to determine the range of discharge voltages and currents and the amplitude and spectral characteristic of electromagnetic interferences produced by these discharges for onboard antennas.

A conical meter of the energy characteristics of laser radiation containing two spatially separated groups of thermopiles is proposed. It is shown that an error of the detector’s zone characteristic of less than 1% may be achieved by appropriate selection of the branch resistance in the circuit of the voltage source which is the most sensitive element to heating.

The problem of vibrations arising during the operation of gas transmittal unit compressors is an urgent task in designing a rotor constructor. Existing approaches do not allow predicting the vibration probability in every operating mode. The article presents a new 2FSI approach allowing a designer to take into account the previously omitted factor of gas and structure interaction. The current level of high-performance computing systems allows using the 2FSI approach for complex systems such as a gas transmittal unit centrifugal compressor. The article presents the numerical calculation results of the gas transmittal unit compressor stage. The results were, obtained using the PNRPU high-performance computing complex (peak performance 24 TFLOPS). In addition, the paper provides the estimated computation time when using different core numbers.

The improved national primary standard for the unit of average laser radiation power GET 28–2013 is described. It can be used to provide metrological support for unity of measurements of the energy characteristics of semiconductor lasers and laser diodes that have high divergences and fairly high output radiation instability.

An experimental setup was devised allowing high-accuracy radiation power measurements in the range of the order of 10−18–10−15 W. The use of a calibrated Fresnel prismatic attenuator in the design minimizes the error in determining the mean number of photos in each radiation pulse. Results are presented for measurements of the positive measure operator for a Hamamatsu H7422-40 photoelectric multiplier.

The NASA spacecraft New Horizons allowed us to refine many physical, chemical, topographic, and geological characteristics of main bodies of the Pluto – Charon system significantly. Their sizes have been clarified. Their shapes were approximated by triaxial ellipsoids. But measurement errors of the axes differences a − c , a − b have exceeded their values. So the asphericity of the figures was not revealed. The same concerns the asphericity of the gravitational fields of Pluto and Charon. So measurements during future space missions must be more accurate. To evaluate the necessary precision we need bilateral theoretical boundaries of the possible values of polar and equatorial oblatenesses α = ( a − c ) / a , β = ( a − b ) / a , as well as the second zonal and sectorial harmonics I 2 , I 22 for both bodies. In the present paper we have obtained them under the assumption of the hydrostatic equilibrium of the Pluto and Charon figures. Pressure, centrifugal forces, and gravity (tidal interaction included) were taken into account. It turns out that the influence of rotation and tides are comparable; tides change the Charon shape more than the Pluto one; dimensionless quantities α, β, I 2 , I 22 are of the order of 10 - 5 ÷ 10 - 4 for Pluto, and 10 - 4 ÷ 10 - 3 for Charon.

A method by means of which the unit of radiation power may be reproduced and transferred from a reference to a verified receiver under the conditions of substantial instability of laser radiation is proposed. Experiments that correspond to the calculations are performed and an estimator of the error of the proposed method for laser radiation with instability about 10% is given.

The configurations of a four-prism attenuator that provide a compact construction and greatly simplify its adjustment and assembly are considered. It is shown that the most successful configuration is a four-prism configuration with pairwise parallel working faces, for which the direction of propagation of the beam is preserved. This provides an intermediate beam for monitoring the polarization and attenuation factor of the incident radiation when calibrating the attenuator.

A new method of processing the experimental current-voltage characteristics of photodiodes using reference points is proposed. By comparing a trap detector, developed at the All-Russia Research Institute of Optophysical Measurements based on Hamamatsu S6337 photodiodes with an HH-03-1337 trap detector, certified using a cryogenic radiometer at the PTB, an experimental value of the internal quantum efficiency of the Hamamatsu S6337 photodiode is obtained.

The losses in a trap detector resulting from absorption of part of the diffusely scattered laser radiation in its walls are analyzed. The results of measurements of the indicatrix of diffusely scattered radiation from the working surfaces of Hamamatsu S6337 and S1337 photodiodes are presented. An approximate model of the propagation of radiation in a trap detector, taking into account the actual shape of the scattering indicatrix, is constructed. The effect of the number of diffuse radiation scattering events and the number of its reflections on the accuracy with which the loss is calculated and their dependence on the polarization of the incident laser radiation are investigated.

The results of high-precision measurements of the current–voltage characteristics of a number of silicon photodiodes are presented. It is established experimentally that random fluctuations of the photodiode temperature have the greatest effect on the measurement accuracy. A temperature stabilization method is proposed, based on the use of the photodiode itself as a temperature sensor and which enables the error in measuring the voltage and current in the photodiode to be reduced by a factor of 103. The results obtained are compared with known theoretical models. It is shown that the one-dimensional model of the photodiode (PC1D) is much more accurate than the Schottky equation.

A calibrated polarization-independent Fresnel attenuator of laser radiation power based on two Dove prisms is proposed and implemented. A method of alignment of such an attenuator relative to the axis of the laser beam and a method of determining the principal directions of polarization of the laser radiation is proposed. By means of model calculations it is shown and experimentally confirmed that imperfections in the manufacture of the prisms and assembly of the attenuator may be compensated by rotating the structure by given angles accompanied by corresponding variations in the total reflection factor of the system.

The effect of measurement errors in the current-voltage characteristics on the accuracy with which the radiation power q absorbed by the photodiode is determined is investigated theoretically. A procedure for measuring the current-voltage characteristic using exponential averaging is proposed, which enables experimental curves to be obtained that are uniform with respect to the measurement of the noise. Statistical distributions of the quantity q are presented from which the systematic and random errors due to the measurement noise are determined.

It is proposed for the first time that a number of basic characteristics of an optically thick photoelectric diode may be determined from its current-voltage characteristic. It is shown that it is theoretically possible to determine the internal quantum efficiency of a photodiode by means of model calculations. The solution of the inverse problem is based on a comparison of theoretical dependences obtained with the use of the PC1D program with “experimental” current-voltage characteristics.

This work examines an attenuator of laser radiation based on four Dove prisms, which is much more efficient in comparison with two cascades of a di-prismatic attenuator. In this case, not only is its alignment and assembly significantly simplified, but also the consistency of the construction becomes evident. It turns out that the most optimal configuration of a four-prismatic attenuator is a pair-parallel one. This configuration, compared with a pair-perpendicular one, provides exchangeability of the di- and the four-prismatic model of the attenuator, maintains the direction of propagation of the radiation, and has a reference beam to control an attenuation coefficient in the operation process of the attenuator.

This work presents an effectively implemented calibrated polarization-independent Fresnel attenuator of laser radiation power built on the basis of two Dove prisms. A method of the attenuator’s alignment with a laser beam axis as well as of determining the main axes of laser radiation polarization is herein demonstrated. It is shown and experimentally proved that using model calculations the prisms’ manufacturing and assembly imperfections can be compensated by the attenuator’s rotation by certain angles and a corresponding change of the system’s total reflection coefficient.

This paper, for the first time, suggests a method of determining internal quantum efficiency of an opaque p+nn+ photodetector and some of its characteristics based on a comparison between experimental measurements of photodetector's voltage-current characteristics and characteristics calculated with PC1D. For our research we chose a silicon photodetector Hamamatsu 1337. It was necessary that reflection coefficient of the front surface of the photodetector is known. The inverse problem solution consisted in determination of following parameters of the photodiode: intensity of incident radiation (q), background doping value (n), peak value of front doping (N), depth factor (L) and front surface recombination velocity (S). The shape of doping profile was figured in the form of complimentary error function. For "experimental" curves we used dependencies derived from voltage-current characteristics calculated by PC1D with nominal parameters values. Variation range represented almost one order of magnitude. The problem consists of the fact that there is an infinite set of local minimums corresponding to the selected initial points in a 5-dimensional space of variables. Hill climbing algorithm was used to find local minimums. A special algorithm to find the absolute minimum is presented in this article. Search for absolute minimum among many local minimums was done through method of consecutive approximations toward the minimum of mean square deviation. From performed calculations, we established that value of incident radiation (q) (and, as result, interior quantum efficiency of the photodiode) can be determined with 0.014% accuracy.

Sufficient BS signal level and minimal interferences at SS receiver at "uncertain" areas are possible when using high-altitude panel antennas with narrow radiation pattern and insignificant side lobes in horizontal plane. Panel antenna possesses such properties. It represents horizontal grid made of zigzag antennas.

The paper presents the results of a study of the main characteristics of coaxial antennas used for receiving and transmitting circularly polarized waves in two separate frequency bands. The method of determining the geometric parameters of these antennas under given requirements is introduced.

The time dependences of the gain of vibrational-rotational lines of the CO molecule were investigated experimentally for the first time in the case of pulsed electron-beam-controlled excitation by ionization of carbon monoxide cooled to cryogenic temperatures. The Patel formula was used to calculate the temperature rise of the active medium during the pumping process. The efficiency of the vibrational excitation of CO for E/N = 2--4 kVxcm/sup -1/xamagat/sup -1/ was estimated to be 70--80%.