In this paper, using the Richards-Wolf equations, we analyze focusing circularly polarized light with flat diffractive lenses. It is shown that as numerical aperture of lens increases, size focal spot first decreases and then begins to grow. The minimum observed at NA=0.96 (FWHM=0.55λ). With a further increase in lens, growth longitudinal component leads an spot. When replaced by aplanatic mono...

We investigate a two-dimensional low F-number dual micro-axilens array with binary structures based on a rigorous electromagnetic theory. The focal characteristics of a binary dual micro-axilens array (BDMA), including axial performances (focal depth and focal shift) and transverse performances (focal spot size and diffraction efficiency), have been analyzed in detail for different F-numbers, d...

X-ray mirrors are widely used at synchrotron radiation sources for focusing X-rays into focal spots of size less than 1 µm. The ability of the beamline optics to change the size of this spot over a range up to tens of micrometres can be an advantage for many experiments such as X-ray microprobe and X-ray diffraction from micrometre-scale crystals. It is a requirement that the beam size change s...

The electron field-emission properties of carbon nanotubes enable the fabrication of cold cathodes for a variety of vacuum device applications. The utilization of these cathodes is an attractive alternative for the replacement of thermionic or hot cathodes for generating X-rays. Miniature X-ray tubes have been fabricated using triode-style carbon nanotubebased cathodes. In this paper we report ...

Lensed fiber optics is of great importance to many applications such as optical sensing, optical coupling, laser trapping etc. In this paper we have demonstrated a unique method to fabricate liquid-core lensed fibers by filling UV curable adhesive into hollow fibers, and to control the focal length and spot size by pumping liquid into or out of the fiber end. In experiment, tuning of focal leng...

A hard x-ray Fresnel zone-plate-based microprobe has been designed and integrated into a Newport kappa diffractometer for microdiffraction studies at the 2ID-D beamline at the Advance Photon Source. The microprobe employs 10 cm and 40 cm (focal length at 8 keV) zone plates to provide high and moderate focusing power, respectively. Each zone-plate assembly has two identical zone plates stacked t...

As interventional procedures become more complicated, the need for accurate quantitative vascular information increases. In response to this need, many commercial vendors provide techniques for measurement of vessel sizes, usually based on derivative techniques. In this study, we investigate the accuracy of several techniques used in the measurement of vessel size. Simulated images of vessels h...

Pupil filters have the capability to arbitrarily narrow the central lobe of a focal spot. We decompose the focal field of a confocal-like imaging system into optical eigenmodes to determine optimized pupil functions, that deliver superresolving scanning spots. As a consequence of this process, intensity is redistributed from the central lobe into side lobes restricting the field of view (FOV). ...

The extensive lit’erature on theoretical and experimental investigations of superbroadening in small scale filaments produced by self-focussed light pulses has been reviewed by Akhmanov et al. [ 11. The interpretation of this frequency broadening in terms of moving focal spots has been reviewed more recently by Low and Shen [2]. In all of this work the diameter of the filaments, or the size of ...