Introduction: Dental panoramic radiography (DPR) is one of the most frequent diagnostic X-ray procedures, the application of which is currently on a growing trend. During DPR, several radiosensitive tissues, such as the lens of the eyes, parotid gland, and thyroid gland, contribute to the radiation field, and it is necessary to monitor their received dose. The aim of t...

We consider the problem of quantum scattering of a localized wave packet by a weak Gaussian potential in two spatial dimensions. We show that, under certain conditions, this problem bears close analogy with that of focusing (or defocusing) of light rays by a thin optical lens: Quantum interference between straight paths yields the same lens equation as for refracted rays in classical optics.

In 1968, Veselago predicted that a thin film composed of a material with a negative refractive index would act as a flat lens [Sov. Phys. Usp. 10, 509 (1968)]. Hyperbolic metamaterials have been designed that show negative refraction, but the condition of an isotropic refractive index n −1 required to realize a diffraction-limited focus cannot be realized using the hyperbolic dispersion. Here, ...

We present a new approach to solar concentration where sunlight collected by each lens in a two-dimensional lens array is coupled into a shared, planar waveguide using localized features placed at each lens focus. This geometry yields a thin, flat profile for moderate concentration systems which may be fabricated by low-cost roll manufacture. We provide analyses of tradeoffs and show optimized ...

Every astrophysical object (dark or not) is a gravitational lens, as well as a receiver/observer of the light from sources lensed by other objects in its neighborhood. For a given pair of source and lens, there is a thin on-axis tubelike volume behind the lens in which the radiation flux from the source is greatly increased due to gravitational lensing. Any objects which pass through such a thi...

Present-day implant lenses are esssentially thick lens systems. The usual methods by which the required power is assessed involve treating them as thin lens systems, thus giving rise to error. It is possible to avoid such an error by changing the approach to the problem. No attempt need be made to calculate the equivalent power of the implant lens required to produce emmetropia after implantati...

High resolution backscatter electron (BSE) imaging of colloidal gold with field emission scanning electron microscopy (FESEM) depends upon selection of accelerating voltage, beam current, working distance between specimen and backscatter detector, type of backscatter detector, plus the nature and thickness of the metal coating used to improve conductivity and signal collection. BSE imaging of a...

A variable-focus liquid lens using a transparent flat cell is demonstrated. The top substrate has an aperture which is sealed with a thin elastic membrane on the outer surface and the bottom aperture is sealed on the inner surface of the bottom substrate. By applying a pressure to the outer membrane inward causes the liquid to redistribute and swell the inner membrane outward which, in turn, fo...

We examine the three-dimensional intensity distribution of vector Bessel-Gauss beams with general polarization near the focus of a nonaperturing thin lens. Recently reported linearly and azimuthally polarized Bessel-Gauss beams are members of this family. We define the width and focal plane of such a vector beam using an encircled-energy criterion and calculate numerically that, as for scalar b...

Conventional CPV systems focus sunlight directly onto a PV cell, usually through a non-imaging optic to avoid hot spots. In practice, many systems use a shared tracking platform to mount multiple smaller aperture lenses, each concentrating light into an associated PV cell. Scaling this approach to the limit would result in a thin sheet-like geometry. This would be ideal in terms of minimizing t...