Electronic educational resources: how to estimate quality?

Article is devoted to questions of an assessment of quality of electronic educational resources. Authors provide the list of innovative qualities which electronic educational resources, the principles of an assessment of these qualities, and also the main stages of carrying out technical and technological, psychology and pedagogical and design ergonomic examination of an assessment of quality have to possessСтатья посвящена вопросам оценки качества электронных образовательных ресурсов. Авторы приводят перечень инновационных качеств, которыми должны обладать электронные образовательные ресурсы, принципы оценки данных качеств, а также основные этапы проведения технико-технологической, психолого-педагогической и дизайн-эргономической экспертизы оценки качеств

Quantitative assessment of non-conservative radiation forces in an optical trap

The forces acting on an optically trapped particle are usually assumed to be conservative. However, the presence of a non-conservative component has recently been demonstrated. Here we propose a technique that permits one to quantify the contribution of such non-conservative component. This is an extension of a standard optical tweezers calibration technique and, therefore, can easily become a standard test to verify the conservative optical force assumption. Using this technique we have analyzed different-sized optically trapped particles under different trapping conditions. We conclude that the non-conservative effects are effectively negligible and do not affect the standard calibration procedure, unless for extremely low-power trapping, far away from the trapping regimes usually used in experiments.Comment: 8 pages, 4 figures; Europhys. Lett. (EPL) (2009), accepte

Rotational Doppler shift of the phase-conjugated photon

The rotational Doppler shift of a photon with orbital angular momentum $\pm \ell \hbar$ is shown to be an even multiple of the angular frequency $\Omega$ of the reference frame rotation when photon is reflected from the phase-conjugating mirror. We consider the one-arm phase-conjugating interferometer which contains $N$ Dove prisms or other angular momentum altering elements rotating in opposite directions. When such interferometer is placed in the rotating vehicle the $\delta \omega=4 (N+1/2) \ell \cdot \Omega$ rotational Doppler shift appears and rotation of the helical interference pattern with angular frequency $\delta \omega /{2 \ell}$ occurs. The accumulation of angular Doppler shift via successive passage through the $N$ image-inverting prisms is due to the phase conjugation, for conventional parabolic retroreflector the accumulation is absent. The features of such a vortex phase conjugating interferometry at the single photon level are discussed.Comment: 6 pages, 3 figures, submitted to referred journa

Spin angular momentum transfer from TEM00 focused Gaussian beams to negative refractive index spherical particles

We investigate optical torques over absorbent negative refractive index spherical scatterers under the influence of linear and circularly polarized TEM00 focused Gaussian beams, in the framework of the generalized Lorenz-Mie theory with the integral localized approximation. The fundamental differences between optical torques due to spin angular momentum transfer in positive and negative refractive index optical trapping are outlined, revealing the effect of the Mie scattering coefficients in one of the most fundamental properties in optical trapping systems

Quantum formulation for nanoscale optical and material chirality: symmetry issues, space and time parity, and observables

To properly represent the interplay and coupling of optical and material chirality at the photon-molecule or photon-nanoparticle level invites a recognition of quantum facets in the fundamental aspects and mechanisms of light-matter interaction. It is therefore appropriate to cast theory in a general quantum form, one that is applicable to both linear and nonlinear optics as well as various forms of chiroptical interaction including chiral optomechanics. Such a framework, fully accounting for both radiation and matter in quantum terms, facilitates the scrutiny and identification of key issues concerning spatial and temporal parity, scale, dissipation and measurement. Furthermore it fully provides for describing the interactions of light beams with a vortex character, and it leads to the complete identification of symmetry conditions for materials to provide for chiral discrimination. Quantum considerations also lend a distinctive perspective to the very different senses in which other aspects of chirality are recognized in metamaterials. Duly attending to the symmetry principles governing allowed or disallowed forms of chiral discrimination supports an objective appraisal of the experimental possibilities and developing applications