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At least 397 records · Page 22

A laser gyro with a four-mirror square resonator: formulas for simulating the dynamics of the synchronisation zone parameters of the frequencies of counterpropagating waves during the device operation in the self-heating regime

For a laser gyro with a four-mirror square resonator we have developed a mathematical model, which allows one to simulate the temporal behaviour of the synchronisation zone parameters of the frequencies of counterpropagating waves in a situation when the device operates in the self-heating regime and is switched-on at different initial temperatures. (laser gyroscopes)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Semiconductor laser gyro with optical frequency dithering

The semiconductor laser gyro is described, in which the optical frequency dithering implemented by intracavity phase modulation suppresses the frequency lock-in and provides the interference of multimode radiation. The sensitivity of the device amounted to 10–20 deg h{sup -1}. (laser gyroscopes)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Frequency response of a gas ring laser with a variable-sign frequency bias in the case of frequency nonreciprocity comparable with the bias amplitude

The dependence of the beat frequency of counterpropagating waves on the rotation rate is studied theoretically and experimentally in a gas ring laser (GRL) with a Zeeman effect-based, variable-sign frequency bias. Use is made of magneto-optical biases of two types, namely, a rectangular (meander) bias and a combined bias consisting of fast and slow meanders. At high rotation rates, when the frequency nonreciprocity determined by the rotation rate is close in magnitude to the amplitude of the variable-sign frequency bias, the dynamic locking bands take maximum values and there arise the most extensive deviations of the frequency response from the ideal response. Comparison of experimental and theoretical results for the widths of dynamic bands that appear in this region of the measured rotation rates shows good agreement between theory and experiment. The results suggest that the frequency response of a GRL in this region can be described by one differential equation for the phase difference of counterpropagating waves. (laser gyroscopes)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

VLBI FOR GRAVITY PROBE B. III. A LIMIT ON THE PROPER MOTION OF THE 'CORE' OF THE QUASAR 3C 454.3

We made very long baseline interferometry observations at 8.4 GHz between 1997 and 2005 to estimate the coordinates of the 'core' component of the superluminal quasar, 3C 454.3, the ultimate reference point in the distant universe for the NASA/Stanford Gyroscope Relativity Mission, Gravity Probe B (GP-B). These coordinates are determined relative to those of the brightness peaks of two other compact extragalactic sources, B2250+194 and B2252+172, nearby on the sky, and within a celestial reference frame (CRF), defined by a large suite of compact extragalactic radio sources, and nearly identical to the International Celestial Reference Frame 2 (ICRF2). We find that B2250+194 and B2252+172 are stationary relative to each other, and also in the CRF, to within 1{sigma} upper limits of 15 and 30 {mu}as yr{sup -1} in {alpha} and {delta}, respectively. The core of 3C 454.3 appears to jitter in its position along the jet direction over {approx}0.2 mas, likely due to activity close to the putative supermassive black hole nearby, but on average is stationary in the CRF within 1{sigma} upper limits on its proper motion of 39 {mu}as yr{sup -1} (1.0c) and 30 {mu}as yr{sup -1} (0.8c) in {alpha} and {delta}, respectively, for the period 2002-2005. Our corresponding limit over the longer interval, 1998-2005, of more importance to GP-B, is 46 and 56 {mu}as yr{sup -1} in {alpha} and {delta}, respectively. Some of 3C 454.3's jet components show significantly superluminal motion with speeds of up to {approx}200 {mu}as yr{sup -1} or 5c in the CRF. The core of 3C 454.3 thus provides for GP-B a sufficiently stable reference in the distant universe.

79 ASTRONOMY AND ASTROPHYSICS↗

Geometric Phase in Anisotropic Kepler Problem: Perspective for Realization in Rydberg Atoms

We predict a gyroscopic effect that can be demonstrated with Rydberg atoms following the dynamics of a Kepler Hamiltonian with an additional uniaxial anisotropy induced by optical ponderomotive force. This effect is analogous to the rotation of the Foucault pendulum in response to the Earth’s rotation. Furthermore, we argue that in Rydberg states with a large principal quantum number a similar geometric angle can be generated by mechanical rotations of an atomic-optical setup on timescales between 1 μ⁢s and 1 ms.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

MO-FG-303-04: A Smartphone Application for Automated Mechanical Quality Assurance of Medical Accelerators

Purpose: The mechanical quality assurance (QA) of medical accelerators consists of a time consuming series of procedures. Since most of the procedures are done manually – e.g., checking gantry rotation angle with the naked eye using a level attached to the gantry –, it is considered to be a process with high potential for human errors. To remove the possibilities of human errors and reduce the procedure duration, we developed a smartphone application for automated mechanical QA. Methods: The preparation for the automated process was done by attaching a smartphone to the gantry facing upward. For the assessments of gantry and collimator angle indications, motion sensors (gyroscope, accelerator, and magnetic field sensor) embedded in the smartphone were used. For the assessments of jaw position indicator, cross-hair centering, and optical distance indicator (ODI), an optical-image processing module using a picture taken by the high-resolution camera embedded in the smartphone was implemented. The application was developed with the Android software development kit (SDK) and OpenCV library. Results: The system accuracies in terms of angle detection error and length detection error were < 0.1° and < 1 mm, respectively. The mean absolute error for gantry and collimator rotation angles were 0.03° and 0.041°, respectively. The mean absolute error for the measured light field size was 0.067 cm. Conclusion: The automated system we developed can be used for the mechanical QA of medical accelerators with proven accuracy. For more convenient use of this application, the wireless communication module is under development. This system has a strong potential for the automation of the other QA procedures such as light/radiation field coincidence and couch translation/rotations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

SECARB Drilling Surveys and Deviation

Daily drilling reports and surveys, deviation data, and gyroscopic surveys from wells CFU31F1, CFU31F2, and CFU31F3 collected from Cranfield oil field in Mississippi as part of SECARB project.

carbon capture↗