Abstract: In one aspect, the present invention generally provides methods for fabricating substrates for use in a variety of analytical and/or diagnostic applications. Such a substrate can be generated by exposing a semiconductor surface (e.g., silicon surface) to a plurality of short laser pulses to generate micron-sized, and preferably submicron-sized, structures on the surface. The structured surface can then be coated with a thin metallic layer, e.g., one having a thickness in a range of about 10 nm to about 1000 nm.

Abstract: In one aspect, the present invention generally provides methods for fabricating substrates for use in a variety of analytical and/or diagnostic applications. Such a substrate can be generated by exposing a semiconductor surface (e.g., silicon surface) to a plurality of short laser pulses to generate micron-sized, and preferably submicron-sized, structures on the surface. The structured surface can then be coated with a thin metallic layer, e.g., one having a thickness in a range of about 10 nm to about 1000 nm.

Abstract: A method and apparatus for monitoring a scanning beam of penetrating radiation, such as a scanning proton beam used to irradiate tissue. The position of the beam is tracked in real time by interposing a scintillator film between a source and an object of irradiation. An imaging detector, in optical communication with the scintillator, provides an output that is indicative of the position of the radiation and its variation with time. The accumulated dose over a scan may also be monitored.

Abstract: Surface enhanced Raman Scattering (SERS) and related modalities offer greatly enhanced sensitivity and selectivity for detection of molecular species through the excitation of plasmon modes and their coupling to molecular vibrational modes. One of the chief obstacles to widespread application is the availability of suitable nanostructured materials that exhibit strong enhancement of Raman scattering, are inexpensive to fabricate, and are reproducible. I describe nanostructured surfaces for SERS and other photonic sensing that use semiconductor and metal surfaces fabricated using femtosecond laser processing. A noble metal film (e.g., silver or gold) is evaporated onto the resulting nanostructured surfaces for use as a substrate for SERS. These surfaces are inexpensive to produce and can have their statistical properties precisely tailored by varying the laser processing. Surfaces can be readily micropatterned and both stochastic and self-organized structures can be fabricated.

Abstract: Diffractive optical elements (DOEs) consisting of a sandwich of two materials are described with an interfacial surface whose relief height impresses the desired optical phase. The two materials have nearly matched indices of refraction, so the interfacial surface has a profile that varies by many wavelengths and is easily fabricated. The materials are chosen such that the refractive index difference and dispersion obey a matching condition that renders the optical path difference (OPD) across the element constant across a broad band of wavelengths. This achromatizes the DOE in that the diffraction efficiency is independent of wavelength. This achromatic property and the fabrication ease allowed by the nearly index matched (NIM) materials enables hybrid refractive-diffractive elements to be fabricated by molding processes for broadband applications.

Abstract: A linear array of photoemitters and photodiodes are positioned on opposite sides of currency paper for denomination and verification determination under transmitted light. The photoemitters are arranged for projecting an image of the indicia printed on the security thread embedded within the currency paper. The photodiodes receive the image and connect with a processor circuit which determines the presence or absence of the security feature, reads the denomination indicia and correspondingly provides indication thereof. The processor contains stored information identifying currency denomination and a comparison is made at the time of verification to also determine the denomination of the proffered currency.

Abstract: A nearly index matched (NIM) optic is formed from at least two elements having indices of refraction that are substantially the same over a given range of wavelengths. The optical cell can have matched solid and fluid lenses in which the solid has at least one curved interface in contact with the fluid. The solid and fluid share a boundary with equal but opposite curvature at each point over the aperture of the NIM optic. The effective optical curvature of the boundary is reduced by the difference in the index of refraction between the two elements of the NIM optic. This difference in the index of refraction can be controlled by changing the index of refraction of at least one of the elements so as to change the difference in the index of refraction across the optical boundary.