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Aiming to improve the spatial resolution of a neutron imaging system (NIS) for 14 MeV fusion neutrons, an ideal micron resolution capillary detector filled with a high optical index liquid scintillator was simulated. A threshold for each capillary pixel and a threshold for each cluster were applied to suppress the gamma-induced background. In addition, by using a pattern recognition algorithm and an optimized Hough transform, the accuracy of determining the neutron impinging positions and the dynamic range of this detector were enhanced. For an ideal capillary array detector, the spatial resolution is expected as one capillary size of 20 μ m. The dynamic range of ∼ 1000 is reachable while the accuracy of neutron impinging position determination keeps better than 85%. The ionization quenching, light sharing and energy resolution of the detector were applied to the simulated data to understand the capillary array detector. • A micron resolution capillary array was simulated for 14 MeV fusion neutrons imaging. • Algorithms of neutron impinging position determination were developed. • Smearing effects were considered in the simulation for a realistic detector response. [ABSTRACT FROM AUTHOR]

Abstract: On the strength of the description of scalar diffraction theory, the difference between the sinusoidal grating and the black–white transmission grating in diffraction is caused by the transmittance of aperture. The diffraction experiment of sinusoidal grating in soft X-ray region is simulated by Matlab through the physical formulas is parsed. The conclusion attained in this simulation is that the distance of the 0th and 1st diffraction lines of sinusoidal grating is proportional to the wavelength of the incident light, transfer distance and the grating frequency, and is independent of the amplitude modulation, which affects peak intensity of the 1st diffraction. Additionally the main lobe width of the 1st diffraction is also influenced by the wavelength, transfer distance and grating effective acreage. This provides the theoretical basis for the property testing and the future widening of the application of the sinusoidal grating. [Copyright &y& Elsevier]

Abstract Azimuthal fractal spiral zone plates (AFSZPs) with particular fractal characteristics are proposed which have the ability to increase the number of foci comparing with conventional spiral zone plates. The generated beams possess sequence of optical vortices along the propagation direction with preset resolution. Numerical simulations are carried out under plane wave illumination and the good performance of this fractal diffractive optical elements are verified experimentally based on a programmable phase-only liquid-crystal spatial light modulator (SLM). In addition, the effects on the axial irradiance and resolution of foci caused by variations of parameters are also presented. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a novel concept of modulated width zone plate (MWZP) is proposed to realize a binary Gabor zone plate (GZP) with single focus. By modulating the zones width as sinusoidal random distribution, higher-order foci can be effectively suppressed. The physical design is verified with numerical simulation and demonstration experiments in visible light region. The performance of the modulated width zone plate is determined by the number of zones used. It works well only when enough zones are utilized. The zone plate is easy to be fabricated employing nanofabrication technology, since it is composed of complete zones, similar to Fresnel zone plates (FZP). This work offers new opportunities for x-ray spectroscopy and microscopy in physics research. [ABSTRACT FROM AUTHOR]

Abstract: Schwarzschild microscope at 18.2nm for diagnostics of hot electron transport in femtosecond laser-plasma interaction has been developed. Based on the third-order aberration theory the microscope is designed for numerical aperture of 0.1 and magnification of 10. Mo/Si multilayer films with peak throughput at 18.2nm is designed and deposited by magnetron sputtering method. The 24lp/mm copper mesh is imaged via Schwarzschild microscope, and resolutions of less than 3μm are measured in 1.2mm field. The diagnostics experiment of hot electron transport is performed on 286 TW SILEX-I laser facilities, and the spatial distribution of radiation caused by hot electron is imaged by Schwarzschild microscope. [Copyright &y& Elsevier]