The parametric Doppler effect upon oblique incidence of probe radiation

Transformation of frequency and intensity of probe radiation obliquely incident on a moving inhomogeneity induced by an intense laser radiation in a nonlinear medium is analyzed. The dependences of frequency and intensity of radiation reflected from the inhomogeneity have been found for a variant of frequency dispersion corresponding to collision-free plasma. These dependences possess singularities under conditions corresponding to the Vavilov-Cherenkov effect. The initially weak noise components of probe radiation increase in the reflected radiation up to a considerable value.     

The parametric Doppler effect in quartz glass

Transformation of frequency is analyzed under the parametric Doppler effect in quartz glass in the “optic collider” scheme. In this scheme, intense laser radiation induces moving inhomogeneities of the refractive index in the glass and the probe radiation undergoes the Doppler frequency shift when being reflected from them. The possibilities of transforming the frequency both within the main transparent region and from the main transparent region to the low- and high-frequency regions separated from the main region by absorption peaks in the infrared and ultraviolet spectral ranges are demonstrated.     

Zone structure of regimes of monochromatic reflected radiation in the parametric doppler effect in plasma

The response of multipass schemes, such as a layer of a medium and multiple-beam interferometer to a radiation pulse with an exponential intensity variation, which is equivalent to the complex frequency of the radiation, is analyzed. Stability conditions of the stationary regime of the scheme are determined.     

Birefringence in leucosapphire products upon oblique incidence of rays

Formulas are derived for calculating the refractive index of an extraordinary ray for hemispherical shells fabricated from leucosapphire and its textured analog. These formulas make it possible to determine the local birefringence and the direction of propagation of both rays after refraction on the surface of hemispherical shells and lenses. The influence of the geometry of the position of the optical indicatrix on the birefringence in leucosapphire products with a complex configuration is analyzed.     

Borrmann effect in parametric X-ray radiation

The suppression of the photoabsorption in parametric X-ray radiation by relativistic particles in a crystal is predicted. This dynamical effect caused by the contribution of emitting particle transition radiation to parametric X-ray radiation yield is possible in a crystal with a finite thickness only.     

Application of artificial irregularities for thermal parametric instability excitation for oblique ionospheric radiation

Scientific-Research Institute of Radiophysics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 6, pp. 624–629, June, 1991.     

Geometric doppler effect: spin-split dispersion of thermal radiation

A geometric Doppler effect manifested by a spin-split dispersion relation of thermal radiation is observed. A spin-dependent dispersion splitting was obtained in a structure consisting of a coupled thermal antenna array. The effect is due to a spin-orbit interaction resulting from the dynamics of the surface waves propagating along the structure whose local anisotropy axis is rotated in space. The observation of the spin-symmetry breaking in thermal radiation may be utilized for manipulation of spontaneous or stimulated emission.     

大角度斜入射情况下的猫眼效应激光反射特性

基于角谱衍射理论,采用2维离散傅里叶变换和将双衍射孔径进行投影合并的方法,推导了斜入射情况下猫眼效应反射光的衍射传输过程,通过数值计算分析了入射角和衍射距离对衍射光场分布的影响规律,并实验验证了入射角的影响规律。结果表明,这种方法能够准确描述大角度入射时的反射光衍射光场分布,入射角对其衍射光场分布模式的影响相当于增大了衍射距离。依据入射角与衍射光场分布模式之间的对应关系,可对猫眼目标进行参数识别研究。     

大角度斜入射情况下的猫眼效应激光反射特性

基于角谱衍射理论,采用2维离散傅里叶变换和将双衍射孔径进行投影合并的方法,推导了斜入射情况下猫眼效应反射光的衍射传输过程,通过数值计算分析了入射角和衍射距离对衍射光场分布的影响规律,并实验验证了入射角的影响规律。结果表明,这种方法能够准确描述大角度入射时的反射光衍射光场分布,入射角对其衍射光场分布模式的影响相当于增大了衍射距离。依据入射角与衍射光场分布模式之间的对应关系,可对猫眼目标进行参数识别研究。     

Transition radiation,Cerenkov radiation and energy losses of relativistic charged particles traversing thin foils at oblique incidence

Semiclassical relativistic energy losses and the transition radiation are calculated for fast charged particles (e.g. electrons) traversing a thin dielectric foil at oblique incidence. The transition radiation formula is generalized for foils with spatial dispersion. This formula for oblique electron incidence is of particular interest for the observation of Cerenkov radiation, emitted from a dielectric foil. The emission of Cerenkov radiation is discussed for varying electron incidence angle and foil thickness by the aid of numerical computations.     

Excitation and radiation of an accelerated detector and anomalous doppler effect

The excitation of a uniformly accelerated detector moving in a vacuum has been widely discussed in recent years. The aim of the present paper is to point out that such an excitation and the associated radiation are similar to those occuring in the region of anomalous Doppler effect which takes place when a detector is moving at a constant superlight velocity in a medium.     

Motion of localized structures in the case of oblique incidence of radiation on a nonlinear interferometer

For wide-aperture interferometers filled with a medium with threshold nonlinearity and excited by external radiation, the transverse profile of the field of localized structures in the form of solitons and dissitons is found when taking spatial filtering into account. The drag coefficient determining the velocity of transverse motion of a single dissiton in the case of oblique incidence of external radiation is analytically calculated.     

Dynamical-diffraction effects in parametric radiation

An analytic theory is developed for dynamical-diffraction effects in x-ray radiation from a relativistic electron traversing a thin single crystal. It is shown that such dynamical effects may be responsible for a glaring discrepancy between recent experimental data and the traditional theory of parametric x-ray radiation.     

Anomalous doppler effect and induced undulator radiation in crossed electric and magnetic fields

We consider the radiation processes in crossed fields similar to the radiation in the anomalous Doppler effect considered by V. L. Ginzburg and I. M. Franck in 1947. It is shown that under the anomalous Doppler effect in crossed fields the electron which passes to a higher Landau level in the radiation takes energy from the potential energy of the electric field. The possibility of using such radiation to obtain induced undulator radiation in a system of electrons drifting across the periodic potential is considered. It is demonstrated that this radiation can occur even in the case of a large spread of electron velocities. This result is important for semiconductor systems with a periodic potential (superlattices). Institute of Physics of Microstructures, Russian Academy of Sciences, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, Nos. 1-2, pp. 86–100, January–February, 1997.     

弯折波导杆的超声斜入射方法*

波导杆技术是一种有效的超声辅助检测方法,在提升高温关键承压设备安全运行方面具有重要作用。现有的波导换能器因直入式发射声波,常被用来在线监测壁厚的腐蚀进程,难以对指定方向的缺陷进行有效检测。为了解决这个难题,基于斯涅耳定理以及导波的频散特性提出了一种弯折结构的波导杆来实现超声斜入射。首先分析了弯折波导杆中水平剪切波的传播特性,探究了波导杆的厚度、弯折角度对杆中声波传播的影响规律;然后,进一步研究了弯折波导杆在半无限空间内的声束指向性;最后通过一对弯折波导杆在线检测结构内部缺陷的试验证明了波导超声斜入射的应用价值。研究结果为基于斜入射技术的波导超声在线监测提供了坚实的理论基础。