Beam delivery system with a non-digitized diffractive beam splitter for laser-drilling of silicon

We report a beam-delivery system consisting of a non-digitized diffractive beam splitter and a Fourier transform lens. The system is applied to the deep-drilling of silicon using a nanosecond pulse laser in the manufacture of inkjet printer heads. In this process, a circularly polarized pulse beam is divided into an array of uniform beams, which are then delivered precisely to the process points. To meet these requirements, the splitter was designed to be polarization-independent with an efficiency>95%. The optical elements were assembled so as to allow the fine tuning of the effective overall focal length by adjusting the wavefront curvature of the beam. Using the system, a beam alignment accuracy of<5 μm was achieved for a 12-mm-wide beam array and the throughput was substantially improved (10,000 points on a silicon wafer drilled in ~1 min). This beam-delivery scheme works for a variety of laser applications that require parallel processing.     

Synthesis and characterization of stoichiometric NiCo nano particles dispersible in both aqueous and non aqueous media

Oleic acid (OA) coated stoichiometric NiCo (50:50) nanoparticles, with and without polyvinylpyrrolidone (PVP) coating, dispersible in aqueous and non aqueous media have been synthesized by a polyol process for the first time. Structural studies by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed the formation of an impurity free face centred cubic phase NiCo alloy. EDS analysis confirmed nearly 50:50 alloy composition. The magnetization, as a function of field and temperature, of these samples showed a soft ferromagnetic nature. The novelty of our method is that the particles are dispersible in non aqueous and aqueous media, which will facilitate preparation of films of these particles.     

Coordinates problem of Hawking radiation derivation in a Kerr–Newman black hole using Hamilton–Jacobi equation

Hawking radiation from a Kerr–Newman black hole is investigated using Hamilton–Jacobi method more deeply. A direct computation will lead to a wrong result via Hamilton–Jacobi method. However, when the well-behaved Painleve coordinate system and Eddington coordinate system are considered, we can get the correct result. The reason of the discrepancy between naive coordinate and well-behaved coordinates is also discussed.     

Structure,equation of state and elasticity of crystalline HNIW by molecular dynamics simulations

We have performed theoretical investigations on the structure, equation of state (EOS), elasticity, and mechanical properties of 2, 4, 6, 8, 10, 12-Hexanitrohexaazaisowurzitane (HNIW) energetic material by molecular dynamics (MD) simulations. The lattice parameters and equations of state of the four polymorphs (ε-, γ-, β-, and α-HNIW) under high pressure are calculated. Our calculated results agree with the previous experiments and theoretical calculations. Meanwhile, the elastic constants and some other mechanical properties of the most stable ε-HNIW under high pressure and temperature are predicted successfully.     

Quantum Anomaly and Hawking Radiation of Charged and Magnetized Reissner-Nordström de Sitter Black Hole

The recent work of Robinson and Wilczek that Hawking radiation can be determined by the compensating fluxes is extended to the charged and magnetized Reissner-Nordström de Sitter black hole. We reconstruct the electromagnetic field tensor and the Lagrangian of the field corresponding to the source with electric and magnetic charges to redefine an equivalent charge and gauge potential. We construct the effect field theory between the event horizon and cosmological horizon to respectively determine the compensating fluxes from them, which are shown to exactly equal to those of Hawking radiation, by the covariant anomaly cancellation conditions.     

Preparation and Characterization of Polypyrrole/Ferrospinel Nanocomposite by W/O Microemulsion Pathway

A polypyrrole/ferrospinel(NiFe₂O₄) nanocomposite was prepared by the in situ chemical oxidizing of pyrrole in the presence of NiFe₂O₄ nanoparticles in water-in-oil (w/o) microemulsion. The structural, morphological, and magnetic properties of the as-prepared polypyrrole/NiFe₂O₄ nanocomposite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and magnetic measurements. XRD and FTIR revealed the presence of NiFe₂O₄ in the nanocomposite. SEM and TEM images illustrated that polypyrrole was coated on the NiFe₂O₄ surface. The electromagnetic parameters, such as conductivity, saturation magnetization, and coercivity of NiFe₂O₄ nanoparticles varied after coating with polypyrrole.     

Studies on the interaction between scopoletin and two serum albumins by spectroscopic methods

The interactions of scopoletin to bovine serum albumin (BSA) and human serum albumin (HSA) have been investigated by spectroscopic methods. The fluorescence tests indicated that the formation mechanism of scopoletin–BSA/HSA complexes belonged to the static quenching. The displacement experiments suggested that scopoletin primarily bound to tryptophan residues of BSA/HSA within site I (subdomain IIA). The binding distance of scopoletin to BSA/HSA was 2.38/2.34 nm. The thermodynamic parameters (ΔG, ΔH and ΔS) calculated on the basis of different temperatures revealed that the binding of BSA–scopoletin was mainly depended on van der Waals interaction and hydrogen bond, and yet the binding of HSA–scopoletin was strongly relied on the hydrophobic interaction and electrostatic interaction. The results of synchronous fluorescence, 3D fluorescence, UV–vis absorption, and FT-IR spectra showed that the conformations of BSA and HSA altered with the addition of scopoletin. In addition, the effects of some common ions on the binding constants of scopoletin to proteins were also investigated.     

Squeezing and entanglement of a two-mode field in a four-level tripod atomic system

The interaction of a collection of N four-level tripod configuration atoms with two orthogonally polarized probe fields is investigated. Under the condition of electromagnetically induced transparency (EIT), we calculate the squeezing and entanglement spectra of the output probe fields. By analyzing the output spectrum, we find that the squeezing and entanglement of the probe fields can be well-preserved after passing through the optically thick medium. Additionally, the effects of the ground state dephasing rates of the atoms on the entanglement and squeezing of the output two-mode squeezed fields are investigated. It is shown that the dephasing rates will degrade the entanglement and squeezing, and these quantum properties can be lost when the dephasing rates increase up to a certain value. This will be useful in the quantum computation and quantum communication.     

A comparative study of the propagation of vectorial nonparaxial beams in the use of different approaches

Starting from the vectorial Rayleigh diffraction integral formula and using a simple expansion of the nucleus in the Rayleigh formula, an analytical propagation equation of vectorial nonparaxial Gaussian beams in free space is derived, which permits us to perform numerical calculations in comparison with the expression derived by Ciattoni et al. and with the direct numerical integration of the Rayleigh formula. It is found that as usual the use of expansion of vectorial Rayleigh diffraction integral is sufficient to provide satisfactory numerical results as compared with the direct integration of the Rayleigh formula. The above two analytical expressions are valid under certain conditions, however both are applicable in the far field.