[en] The concept of constructing precision laser goniometer systems, based on integrating a ring laser and an optical angle sensor with the holographic principle of angular scale recording is considered. The concept implies the application of the cross-calibration procedure, aimed at determination of systematic components of the errors of angle sensors, used in the system. The results of the presented system studies demonstrate the error of angular measurements amounting to ∼0.01''. The results of implementing the proposed concept in the creation of a standard system of the plane angle unit of rigid rotation and the measuring and computing complex for automated control of digital angle transducers with high digit capacity are briefly presented. (laser optics 2012)

[en] The methods and instruments of dynamic laser goniometry developed over many years of research carried out in the St Petersburg State Electrotechnical University [formerly Leningrad Electrotechnical Institute (LETI)] are considered. The primary sources of error and conditions for error minimisation are identified and evaluated. The laser goniometers developed have been used to certify optical polygons and angular position sensors, to estimate angular motion parameters of various objects, and specifically to measure angular positions of crystals in the unique diffraction spectrometer built at the St Petersburg Institute of Nuclear Physics (PINP) of the Russian Academy of Sciences. Modern measurement technologies combined with a self-calibrated ring laser allowed a large amount of measuring information to be accumulated over a short (1 to 5 min) period of time and ensured that the random component of angle measurement uncertainty is as small as 0.02 to 0.03 in the 0 - 360⁰ range. On the basis of inertial properties of a ring laser, a new concept was proposed for constructing a new generation of measuring systems intended to estimate complex angular motions and to provide dynamic calibration of multiple-axis test beds, large-scale antenna systems, telescopes, and other objects. (laser gyroscopes)

[en] The kinetics of spontaneous cavitation in liquid nitrogen at positive and negative pressures has been studied in a tension wave formed by a compression pulse reflected from the liquid–vapor interface on a thin platinum wire heated by a current pulse. The limiting tensile stresses (Δp = p_s–p, where p_s is the saturation pressure), the corresponding bubble nucleation frequencies J (10"2"0–10"2"2 s"–"1 m"–"3), and temperature induced nucleation frequency growth rate G_T = dlnJ/dT have been experimentally determined. At T = 90 K, the limiting tensile stress was Δp = 8.3 MPa, which was 4.9 MPa lower than the value corresponding to the boundary of thermodynamic stability of the liquid phase (spinodal). The measurement results were compared to classical (homogeneous) nucleation theory (CNT) with and without neglect of the dependence of the surface tension of critical bubbles on their dimensions. In the latter case, the properties of new phase nuclei were described in terms of the Van der Waals theory of capillarity. The experimental data agree well with the CNT theory when it takes into account the “size effect.”

[en] The work is devoted to experimental investigation of the vortex effect in the Ranque-Hilsch tube using non-contact methods. The vortex tube, which consists of the slit-type swirler made as accelerating vortex chamber, a working channel with a square cross section, a radial diffuser at the hot outlet and a diaphragm at the cold one was used. For optical diagnostics, the vortex chamber (swirler) was equipped with optical windows. On the basis of measurements by the laser Doppler anemometry method, new experimental information about flow at the entrance of the Ranque-Hilsch vortex tube was obtained. (paper)