Quantitative phase imaging generates the refractive and thickness structure of transparent samples in transmission light microscopy. It is a method that utilises the fact that a phase distribution in one plane has visible outcomes on the intensity of the wave as it propagates. This paper shows equivalent shape imaging results appear possible for through-focal stacks in reflection microscope imaging. Comparison is made to the transmission formulation and images to show the appropriateness of the results.
We describe the theory, fabrication and experimental results of novel, compact optical elements for collimating and/or focusing beams of x-rays or thermal neutrons. These optical elements are solid composites consisting of regular stacks of alternating micro-foils, analogous in action to Soller slits. They are made out of pairs of metals with suitable refractive indices for reflection and/or absorption of the radiation. The performance of these proof-in-principle collimating elements is limited only by the choice of micro-foil materials and the uniformity of their interfaces.
Square-channel capillary, or 'Lobster-eye' arrays have been shown to be the optimum geometry for array optics. This configuration leads to a novel class of conditioning devices for x-ray and neutron beams. We present the first result of the focusing of neutrons with a lead glass square-channel array. This array, designed for soft x-rays, performs comparably with neutrons. Finally, we describe a novel method for the fabrication of glass square channel arrays.
Conditioning neutron and X-ray beams is best achieved with glancing-incidence reflective optics. Square micro-channel arrays offer an increasingly practical geometry for this implementation. We present results for focussing neutrons with two such arrays, one with channel size of 32 micrometer, which places us truly in the microscopic regime. These two arrays, designed for soft X-rays, perform comparably with neutrons.
We describe the fabrication techniques of novel, compact optical elements for collimating and/or focusing beams of X- rays or thermal neutrons. These optical elements are solid composite arrays consisting of regular stacks of alternating micro-foils, analogous in action to Soller slit collimators, but up to three orders of magnitude smaller. The arrays are made of alternating metals with suitable refractive indices for reflection and/or absorption of the specific radiation. In one implementation, the arrays are made of stacked micro-foils of transmissive elements (Al, Cu) coated and/or electroplated with absorbing elements (Gd, Cd), which are repeatedly rolled or drawn and restacked to achieve the required collimation parameters. We present results of these collimators using both X-rays and neutrons. The performance of the collimating element is limited only by the choice of micro-foil materials and the uniformity of their interfaces.
X-ray focusing using square channel capillary arrays is reviewed. We review our theoretical understanding of these devices and go on to examine their potential in the context of x-ray astronomy as an approach to the construction of a lobster-eye telescope. We show that a reasonably small device has the potential, in principle, to improve the sensitivity of wide field of view x-ray telescopes by an order of magnitude. We go on to briefly review our experimental work and indicate that these devices are getting close to realizing their theoretical potential.
X-ray focusing using square channel capillary arrays is reviewed. We present some experimental results obtained using a variety of array configurations and we deduce that channel misalignment and surface roughness are the prime factors limiting the performance of these devices. We present results obtained using a stacked array of commercial precision bore square tubing and deduce that the reflectivity from these unetched surfaces is superior to that from etched micro-channel plate blanks. The improved surface quality implied by this reflectivity result is confirmed using atomic force microscopy. We also present results of a new drawing technique that we have developed.
A novel method is presented for the experimental determination of refractive index profiles for planar media of monotonically decreasing refractive index, such as those used for optical waveguides. The technique is based upon a generalization of the classical experiment of Lloyd's Mirror, involving the interference pattern formed by a point source and its mirage, i.e., its reflection in such a graded planar medium.