Abstract: A photocapacitor device is provided for responding to a photon having at least a specified energy. The photocapacitive device includes a first portion composed of a photocapacitive material; a second portion composed of a non-photocapacitive material; and a depletion region disposed between the first and second portions. The photocapacitive and non-photocapacitive materials respectively have first and second Fermi-energy differences, with the second Fermi-energy difference being higher than the first Fermi-energy difference.

Abstract: A photocapacitor device is provided for responding to a photon having at least a specified energy. The photocapacitive device includes a first portion composed of a photocapacitive material; a second portion composed of a non-photocapacitive material; and a depletion region disposed between the first and second portions. The ph otocapacitive and non-photocapacitive materials respectively have first and second Fermi-energy differences, with the second Fermi-energy difference being higher than the first Fermi-energy difference.

Abstract: A dynamically variable lens is made from actively tunable electromagnetic metamaterial cells. The lens operates on electromagnetic radiation including: radio frequency waves, microwaves, teraherz waves, near infrared waves, infrared waves and visible waves. The focal length of the lens is changed at a selected frequency. In the alternative, the frequency of radiation operated on is changed as a function of time. A third alternative provides precise control of the index of refraction of the lens. The index of refraction is varied progressively across the lens from one edge to the opposite edge causing the radiation to be directed at an angle.

Abstract: In one general aspect, a tunable electromagnetic metamaterial as described herein includes a substrate and an array of split ring resonators formed on the substrate. At least one of the split ring resonators is a capacitively tuned split ring resonator. The capacitively tuned split ring resonator includes a structure having a gap and is formed of an electrically conductive material. The capacitively tuned split ring resonator also includes a region of photo-capacitive material formed in close proximity to the structure such that the capacitance of the metamaterial is changed when illuminated by controlling electromagnetic radiation having a selected range of wavelengths.

Abstract: A method and apparatus for detecting diffraction radiation from a charged particle beam in order to measure parameters that characterize the charged particle beam. The charged particle beam passes near one or more edges, apertures, or interfaces between media of different dielectric constants such that the beam is not intercepted. This generates forward diffraction radiation and reflected diffraction radiation at an angle relative to the direction of the beam. The radiation passes through a focusing system and onto a detector which measures a desired parameter.

Abstract: The invention is a device to measure the emittance of a charged particle beam. The device is capable of providing precise time resolution limited only by the chosen detector. The device allows a complete emittance determination as a function of time. The preferred embodiment of the invention comprises a plurality of thin foils 11 which generate an optical transistion radiation (OTR) pattern 13; a lens system 14 to collect the OTR pattern 13 from the said foils 11: an optical mask 16 to allow passage of the OTR pattern 13 :and a detector array 17 or similar device placed behind the mask 16 which intercepts, senses and measures the point source OTR pattern 13 for each perforation in the mask.

Abstract: A transition radiation interference spectrometer for measuring the energy and divergence of a charged particle beam. Transition radiation is created by placing an interferometer in the path of the charged particle beam. The resulting interference pattern is focused and masked to define an angular element at a fixed angle with respect to the direction of specular reflection. The radiation in the angular element is dispersed into wavelength components. The intensity or amplitude of the wavelength components as a function of wavelength is indicative of the beam's energy and divergence.