Shaomin Wang

Propagation of off-axial Hermite-cosine-Gaussian beams through an apertured and misaligned ABCD optical system

By introducing the hard aperture function into a finite sum of complex Gaussian functions, an approximate analytical expression for the one-dimensional off-axial Hermite–cosine–Gaussian beams passing through an apertured and misaligned paraxially ABCD optical system has been derived. As special cases, the corresponding closed-forms for the off-axial or non-off-axial Hermite–cosine–Gaussian beams passing through apertured or unapertured and misaligned or aligned paraxially ABCD optical systems have also been given. The results provide more convenient for studying their propagation and transformation than the usual way by using diffraction integral directly, which can be straightforward to the two-dimensional case. Some numerical examples are also illustrated.

Development and antifungal evaluation of a food-grade U-type microemulsion.

Aims:  Food‐grade microemulsions have been of increasing interest to researchers as potential delivery systems for bioactive compounds. However, food‐grade microemulsions are difficult to formulate and no microemulsion has been documented for antifungal purpose. The physicochemical characterization of a food‐grade glycerol monolaurate (GML)/ethanol (EtOH)/Tween 80/potassium sorbate (PS)/water microemulsion system and the antifungal activities against Aspergillus niger and Penicillium italicum have been studied in this paper.

Semiconductor laser with beam quality factor M2<1

Abstract Based on the nonparaxial vectorial moment theory of light beam propagation, the beam quality factor M2 of TE0 propagating mode for GaAs/Ga0.7Al0.3As double heterostructure injection laser is analyzed and calculated. The results show that M2 can be smaller than unity if the active layer thickness d is smaller than 0.32 times of wavelength, and there is not a low bound for M2 of semiconductor laser.

Electromagnetic excitation of nano-carbon in vacuum.

Nano-carbon as lighting source is demonstrated in this paper. The characterized nano-radiation from nano-carbon, excited by different lasers in vacuum, is observed when laser intensity is over a threshold. With lower excitation threshold and smaller white light source, nano-carbon is more applicable to be as lighting system than the others in scientific experiments. White light emission of nano-carbon induced by more practicable electromagnetic excitation (microwave) is also demonstrated, which is caused by the faradic heating of the metal substrates, with molecular spectra and better color rendering. Lighting systems comprised of nano-carbon may become one of the considerable directions in optics.

Effect of misalignment on optical fractional Fourier transforming systems

The effect of misalignment on optical fractional Fourier transforming systems is analysed in this paper. Meanwhile, a concept of perturbed fractional Fourier transform is put forward. By using the generalized misaligned diffraction integral formulae for misaligned optical systems, it is shown that the diffraction characteristics for misaligned Lohmanns fractional Fourier transforming systems and quasi-asymmetric inhomogeneous media are able to perform the perturbed fractional Fourier transform and are essentially equivalent. And also, a relative discussion is given.

Propagation of flattened Gaussian beams passing through a misaligned optical system with finite aperture

Summary The propagation of flattened Gaussian beams (FGBs) passing though misaligned optical systems with aperture has been studied in detail. The corresponding approximate equation has been derived, where the rectangular aperture function is expanded into a finite sum of complex Gaussian functions. Numerical examples are given to illustrate the application of the propagation equation and the properties of flattened Gaussian beams passing through a misaligned optical system with aperture are discussed.

Axial superposition of Gaussian spherical beams

A novel model of beam formed by coherent superposition of two correlated Gaussian spherical beams with different centers is presented. This kind of beam has a transverse spreading smaller than a fundamental Gaussian beam. The beam quality factor is smaller than one.

Fresnel number of a regular polygon and slit.

The concept of the Fresnel number is generalized to make it possible to describe the regular polygon and slit illuminated by a homogeneous plane wave. The generalization is based on nonlinear regression of the axial intensity distribution curve. A useful analytical expression for the Fresnel number is presented. A simple experiment to show the different Fresnel numbers in one observation plane is illustrated.

Demonstrations of the diffraction and dispersion phenomena of part Fresnel phase zone plates

The authors report on experimental demonstrations of the diffraction and dispersion phenomena of part Fresnel phase zone plates (FPZPs) by employing a He–Ne laser beam and a white point source. The experimental results have shown that a part square FPZP can behave like a complete circular FPZP, and a part circular FPZP has a focus at 1∕3 f and f with a shift. Some numerical simulations are performed. The simulations and the experiments have shown that the diffraction and dispersion properties of part FPZPs can be well explained by the different diffraction orders.The authors report on experimental demonstrations of the diffraction and dispersion phenomena of part Fresnel phase zone plates (FPZPs) by employing a He–Ne laser beam and a white point source. The experimental results have shown that a part square FPZP can behave like a complete circular FPZP, and a part circular FPZP has a focus at 1∕3 f and f with a shift. Some numerical simulations are performed. The simulations and the experiments have shown that the diffraction and dispersion properties of part FPZPs can be well explained by the different diffraction orders.

Fractional Hankel transform and the diffraction of misaligned optical systems

Under the condition of rotational symmetry fractional Fourier transforms become fractional Hankel transforms. The relationships between the fractional Hankel transform and the diffraction of a misaligned optical system are established in this paper. By settling and discussing the diffraction integral formulae of a misaligned ABCD optical system, the fractional Hankel transform of an input function can be obtained by selecting a suitable reference plane under given conditions.