Volume 60, Nº 8 (2017)

We present the characteristics of GET 55-2017, the State Primary Standard for reproduction and transmission of units of sound pressure and vibrational velocity in a water medium. We consider the operational principles of installations, measurement formulas and the results of the investigation of metrological characteristics.

A new extensive class of binary (0, 1)-sequences is proposed, which includes an infinite set of infinite sets of generalized extended sequences. These sequences are obtained by expanding inversion extended pseudorandom sequences. This enables the creation of coding collimators in integrated-code systems for measuring spatial distributions of radiation sources with the possibility of varying the average transmission and effective implementation of radiation-physics experiments using multiplexed measurements.

We present a schematic diagram of the automated calibration stand 6GS-40M intended for calibration of an intra- and out-of-model six-component strain-gauge balance. The basic features of the stand construction are stated and its elastic model is constructed. The main sources of the occurrence of systematic errors in weights are considered. A technique for calculating the movement of the origin of the stand during the calibration of the balance is described. A technique for calculating loads in the Earth coordinate system is described by recording the equation of equilibrium of forces for an arbitrary position of the calibration device in space.

The characteristics of a laser rangefinder with a wavelength of 1.54 μm having a radiation pulse energy less than the threshold value safe for human eyes are calculated. Two examples of photodetectors with increased sensitivity are given. A system for pumping the laser active element by laser diode lines is proposed which increases the efficiency of the laser emitter and decreases the energy load on the active element.

An analysis of the instability of the frequency of the output signal of a group frequency keeper is presented. The correlation between the signals of the high-frequency oscillators forming the group is taken into account. Formulas for use in calculating the Allan variation of the frequency of the group signal are obtained.

The design of a magnetotransistor with two contacts to the base for the purpose of increasing the sensitivity of a planar magnetotransistor is investigated. The possibility of creating a magnetotransistor with compensation of collector currents based on the use of the technology of heterojunction bipolar transistors is considered.

A new dynamic method of measuring the local value of hardness and contact stiffness at the nanoscale range using a probe in self-oscillation mode at resonant eigenfrequency is proposed. The possibility is shown of measuring the force of contact interaction of a probe with a sample in a range from ten to several hundred μN with shift of the probe’s resonant eigenfrequency, at a resolution up to one hundred nN. The advantage of this method is the absence of a drift component of the measuring signal during the time interval of a test cycle. This ensures operability of the method without special conditions of vibration insulation and thermal insulation that are necessary for instrumental indentation.

Spatial filtration errors of surface texture by means of a Gaussian filter are analyzed. A composite model is used in a mathematical description of surface texture. The analytical dependence of Gaussian filtration error is derived. Errors are investigated in filtration of a sinusoidal wave and surface inclination.

A new femtosecond correlation nonlinear optical profilometer with micron spatial resolution is proposed, in order to increase the measurement accuracy of the heterogeneity profile of a surface at a distance up to 1 km. The principle of operation of this profilometer is based on determining the distance to the scanned object by measuring the time interval between sequences of the base (probing) and reflected femtosecond laser pulses. Thereafter, the profile of a rough surface is reestablished by using the one-dimensional spatial distribution of second-harmonic radiation as the space-time coupling of the sequences of the probing and reflected pulses in a nonlinear crystal is restored. It was shown that the spatial resolution of the profilometer is no greater than 5 μm.

A pulsed magnetic induction meter is developed for testing the static fields of magnets, electromagnets, and solenoids. The instrument error is 2·10^–6 for fields on the order of 25 mT with field inhomogeneities of 7·10^–5 within 1 cm.

A second-generation algorithm designed for implementation of the new method of mirror noise images for separating a useful signal from noise is proposed. By means of the method, a signal-to-noise ratio higher than the limiting values determined by the method of optimum filtration of signals used in classical radio engineering may be obtained. The results of the study of the algorithm show that it yields a substantial gain in the signal-to-noise ratio by comparison with narrow-band filtration of signals and the first-generation algorithm that implements the present method.

A method is presented for detection of magnetic bremsstrahlung on colliding beams in colliders, particularly coherent bremsstrahlung in the area of low-energy photons in collision with high-energy particle beams. The properties of coherent bremsstrahlung and its capability for detection and use of beams in diagnostics are presented.

The possibility of increasing the accuracy of preparing n-pentane calibration gas mixtures by using injection-type chromato-desorption microsystems is investigated. The possibility of obtaining calibration gas mixtures in the range of 4–12 mg/m³ (δ_max = 16%) is shown. It is established that the change in the composition of the mixture during storage for three months is not more than 7%.