Regenerative soot as a source of broad band VUV light

Certain important and pertinent questions have been raised by E. Träbert in his comment on the paper [Eur. Phys. J. D 22, 189 (2003)] by one of us. We provide explanations as well as new and recent data using a calibrated monochromator on the existence of the main intercombination multiplet 233 nm which is the bone of contention. It is shown that there is no conflict with the established atomic physics in the regenerative sooting discharges; only the interpretations are at variance with those of the comment.Received: 30 July 2003, Published online: 30 September 2003PACS: 32.70.Fw Absolute and relative intensities - 34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions - 34.80.Dp Atomic excitation and ionization by electron impact     

Regenerative soot as a source of broad band VUV light by Shoaib Ahmad

The analysis and interpretation of the data presented by S. Ahmad [Eur. Phys. J. D 22, 189 (2003)] are shown to be inconsistent, and are in conflict with established atomic physics.Received: 11 July 2003, Published online: 30 September 2003PACS: 32.70.Fw Absolute and relative intensities - 34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions - 34.80.Dp Atomic excitation and ionization by electron impact     

读出光光源对液晶光阀实验的影响

液晶光阀实验中一般是用带布氏窗的He-Ne激光器作为读出光光源,本文分析了普通He-Ne激光、半导体激光、卤素灯等常见光源在液晶光阀实验中应用的可能性和各自特点并进行了实验验证.     

Interaction of light with a dye-doped nematic liquid crystal

The interaction of linearly and circularly polarized beams with a nematic liquid crystal doped with light-absorbing dyes has been studied by light-diffraction and microprojection methods. It has been found that there is a threshold for the emergence of light-induced anisotropic structures, which, depending on the type of dye, can be axisymmetric or extended in a direction determined by the light field. Possible mechanisms leading to the formation of the anisotropic structures are discussed. Zh. éksp. Teor. Fiz. 111, 2059–2073 (June 1997)     

Investigation of planar photonic crystal band diagrams under the light cone using surface coupling techniques

We report experimental results for the band structure of 2-dimensional triangular photonic crystals etched in SOI wafers. Boundary conditions at the surface and at the border of the etched area of the slab, allow the excitation of guided modes via diffraction phenomena using surface coupling techniques and the determination of the structure band diagram above and below the light cone. These non-destructive techniques, usable for non-active materials, allow fast characterization of technical processes and the location in reciprocal space of areas with unique dispersion properties. PACS 42.70.Qs; 42.25.Fx; 81.70.Ex     

Tuning of full band gap in anisotropic photonic crystal slabs using a liquid crystal

We analyze the tunability of full band gap in photonic crystal slabs created by square and triangular lattices of air holes in anisotropic tellurium background, considering that the regions above and below the slab are occupied by SiO₂ and the holes are infiltrated with liquid crystals. Using the supercell method based on plane wave expansion, we study the variation of full band gap by changing the optical axis orientation of liquid crystal. Our results demonstrate the existence and remarkable tunability of full band gap in both square and triangular lattices, largest band gap and tunability being obtained for the triangular lattice.     

Investigation of a tin liquid metal ion source

In view of its importance in materials research, tin is a metal worth studying in a liquid metal ion source configuration, even if results complement or extend previous work. This is the more so if the new work corrects misconceptions of the past and adds to current thinking. We, therefore, prepared a Sn liquid metal ion source employing a Ni needle to anchor the liquid, cone-shaped, emitter. Source properties, such as the current–voltage curve, the mass spectra of the beam and the energy spread of the main ionic species, were studied in detail. The mass spectra show a considerable amount of Sn clusters, apart from the dominant species, Sn⁺ and Sn⁺⁺. The source was stable down to 1-A emission current, corresponding to an energy spread for the singly charged ions of 7 eV. Theoretical arguments, involving the peak energy deficit of the ion-energy distribution, strongly suggest that both Sn⁺ and Sn⁺⁺ are emitted by direct field evaporation from the liquid surface. The same conclusion is reached from a careful examination of the beam mass spectra of the source. PACS 07.77.Ka; 33.15.Ta; 61.25.Mv     

Electro-optic study of acrylate based holographic polymer dispersed liquid crystals with broad band photosensitivity

We describe the electro-optic (EO) modulation of diffraction in holographic polymer dispersed liquid crystals, recently developed for broad band photosensitivity, ranging from visible to near infrared. More than 90% EO modulation achieved for relatively low electric fields confirms the phase separation and formation of liquid crystal sub-micrometer sized droplets in the polymer matrix. Molecular reorientation induced by the applied voltage and a residual electrical current induced heating are at the origin of the EO modulation.     

Coherent anti-Stokes Raman scattering microscopy with a photonic crystal fiber based light source

A coherent anti-Stokes Raman scattering microscope based on a Ti:sapphire femtosecond oscillator and a photonic crystal fiber is demonstrated. The nonlinear response of the fiber is used to generate the additional wavelength needed in the Raman process. The applicability of the setup is demonstrated by imaging of micrometer-sized polystyrene beads.     

EUV emission from solids illuminated with a laser-plasma EUV source

In this paper a possibility of performing fluorescence experiments in extreme ultraviolet (EUV) using a laboratory EUV source was demonstrated. Usually such measurements are performed using third-generation synchrotrons because of extremely low probability of fluorescence in this wavelength range. In this work a 10 Hz laser-plasma EUV source based on a gas puff target was used. Fluorescent radiation from Al and Si was registered. Despite relatively low spectral resolution, some differences in Si spectra coming from different kind of samples were revealed.     

Nonlinear image self-filtering with liquid crystal spatial light modulator

Nonlinear spatial filtering is realized due to the electro-optical effect in spatial light modulators (SLMs). Optical methods with nonlinear filtering are suggested for various optical applications such as optical inspection of photolithography masks, wavefront sensor, etc. A fast optical response of the SLM allows optical inspection with a video (or faster) rate. The optical system proposed is tolerant to the vibrations and temperature variations because of the dynamic properties of the SLM.     

Experiments on effective source locations and velocity dependence of the broad band noise from a rotating rod

Effective acoustic source positions (observed from the far field) have been located for the broad band noise from a cylindrical rod rotated about its mid-point by measuring the cross spectral density function of two microphone signals on the axis of rotation. Local source position Strouhal numbers could thereby be calculated. On the basis of acoustic power measurements it was demonstrated that the noise may be normalized on a rod tip Strouhal number basis, and that the velocity exponent is nearly constant when plotted against this parameter. The results indicate that vortex shedding like that for stationary cylinders in a cross flow (occurring along the outer $\text{1}\text{3}$ of the rod for a rotational speed of 1000 rpm) is responsible for the high levels of broad band noise in a major peak region. Sources influenced by harmonics of the rod passing frequency were found for frequencies lower than the vortex shedding ones. At higher frequencies broad band noise was found to be emitted from the rod tip area.     

Transversal structure of liquid crystal in a light wave field

The change in the orientation of the director of a nematic liquid crystal in a light wave field under a uniform illumination is analyzed. A system of equations for the distribution of the director angle of inclination is derived for the case of normal incidence. This system accounts for the finite energy of interaction between the nematic and substrate. The dependence of the director distribution profile on the incident light intensity and cohesion energy is studied at fields considerably above the threshold.     

Modulation transfer function of a liquid crystal spatial light modulator

The modulation transfer function (MTF) of a pixelated liquid crystal spatial light modulator (LC-SLM) has been derived as a function of the fill factor. Based on the formula, we have investigated the dependence of the MTF on the orientations and spatial frequency of the input patterns. Furthermore, we have proposed and demonstrated a method for improving the MTF of a LC-SLM.     

扩展光源照明的双光栅系统滤波狭缝对成象莫尔条纹的作用与影响

本文用衍射理论定量分析了扩展光源照明的双光栅系统中滤波狭缝对成象莫尔条纹形成的影响及作用,给出了狭缝的面内及离面位移量与条纹手移量及倾斜角间的关系.