Abstract: A system and apparatus for navigating and tracking a robotic platform includes a non-contact velocity sensor module set positioned on the robotic platform for measuring a velocity of the robotic platform relative to a target surface. The non-contact velocity sensor module set may include a coherent light source that is emitted towards the target surface and reflected back to the coherent light source. Measuring the change in intensity of the reflected coherent light source may be used to determine the velocity of the robotic platform based on the its relationship with the principles of a Doppler frequency shift. A communication unit may also be utilized to transmit data collected from the non-contact velocity sensor set to a computer for data processing. A computer is then provided on the robotic platform to process data collected from the non-contact velocity sensor set.

Abstract: A Compton tomography system comprises an x-ray source configured to produce a planar x-ray beam. The beam irradiates a slice of an object to be imaged, producing Compton-scattered x-rays. The Compton-scattered x-rays are imaged by an x-ray camera. Translation of the object with respect to the source and camera or vice versa allows three-dimensional object imaging.

Abstract: The present invention provides systems and methods for x-ray imaging. In some embodiments, an aperture, or a plurality thereof, are configured to have image transfer functions lacking a zero within a usable spatial frequency range. In further embodiments, the image transfer function is determined according to the shape of the aperture and the usable spatial frequency range is determined according to a usable signal to noise ratio.

Abstract: The present invention provides systems and methods for x-ray imaging. In some embodiments, an aperture, or a plurality thereof, are configured to have image transfer functions lacking a zero within a usable spatial frequency range. In further embodiments, the image transfer function is determined according to the shape of the aperture and the usable spatial frequency range is deter mined according to a usable signal to noise ratio.

Abstract: A quantum-imaging system for detecting photons, including short-wavelength (<1 nm) photons, is provided. A quantum imaging system can include optical read-out and optical means, and can be configured to perform as both a photon counter and a photon spectrometer. A quantum-imaging system can function as a photon counter and be configured to measure photon beam fluences (e.g., in J/cm2) for both strong beams and weak beams, the latter ones, for example, in the intensity range of 1 pJ/cm2sec, or 0.1 ?Sv/h. The quantum-imaging system can also function as a photon spectrometer and can be configured to measure photon energies with high energy resolution such as, for example, 1% of photon energy.

Abstract: A long-period grating with axially-symmetric refractive index modulation and a clean transmission spectrum is formed by exposing an optical fiber to multiple writing beams of infrared light. The writing beams have substantially the same power and converge on the fiber in an axially-symmetric fashion, thus inducing axially-symmetric heating of the fiber. In one configuration, the writing beams are produced by a single reflective element placed next to the fiber. Multiple identical gratings on a number of fibers can be made in parallel using this arrangement by placing the fibers side by side, provided the light is properly focused so that all fibers are uniformly irradiated by the writing beams.

Abstract: A mode coupling device is provided for coupling co-propagating modes in an optical waveguide to provide a gain flattening filter for use with an optical amplifier such as an erbium-doped fiber amplifier. The mode coupling device includes a plurality of long period grating sections having equal spatial periods, with adjacent grating sections separated by an interval of less than 10 periods in length. Also provided is a method for manufacturing the mode coupling device, including a method for determining the parameters of the device and a method for fine tuning the device to provide a loss spectrum closely matching the output spectrum of the optical amplifier. The mode coupling device is useful for flattening the gain of the optical amplifier.

Abstract: A wavelength-selective optical device for coupling of light at predetermined wavelength from one optical fiber waveguide to another using at least two gratings and cladding-mode assisted coupling is disclosed. The transfer of light is performed using intermediate coupling to one or more cladding mode of the waveguides. In the case when the fibers have physically different cladding's, an arrangement for transfer of light from one cladding to another is required. The disclosed coupler has no back-reflection, small insertion loss, and very high channel isolation. The device can be used in wavelength-division multiplexing networks.

Abstract: Techniques and devices based on a wave-guiding element which has a spatial grating pattern that is an oscillatory variation along its optic axis. The wave-guiding element is configured to receive an input optical signal and to produce an output optical signal by reflection within a Bragg reflection band produced by the spatial grating pattern so as to produce time delays of different reflected spectral components as a nonlinear function of spatial positions along said optic axis at which the different reflected spectral components are respectively reflected. Such a wave-guiding element may be a nonlinearly chirped fiber grating A control unit may be engaged to the wave-guiding element and is operable to change a property of the spatial grating pattern along the optic axis to tune at least relative time delays of the different reflected spectral components nonlinearly with respect to wavelength.

Abstract: A wavelength-selective optical device for coupling of the light at predetermined wavelength from one optical fiber waveguide to another using at least two gratings and cladding-mode assisted coupling is disclosed. The transfer of light is performed using intermediate coupling to one or more cladding mode of the waveguides. In the case when the fibers have physically different claddings, an arrangement for transfer of light from one cladding to another is required. The disclosed coupler has no back-reflection, small insertion loss, and very high channel isolation. The device can be used in wavelength-division multiplexing networks.

Abstract: A wavelength-selective optical device for coupling of light at predetermined wavelength from one optical fiber waveguide to another using at least two gratings and cladding-mode assisted coupling is disclosed. The transfer of light is performed using intermediate coupling to one or more cladding mode of the waveguides. In the case when the fibers have physically different claddings, an arrangement for transfer of light from one cladding to another is required. The disclosed coupler has no back-reflection, small insertion loss, and very high channel isolation. The device can be used in wavelength-division multiplexing networks.

Abstract: A nonlinearly chirped fiber grating for achieving tunable dispersion compensation, chirp reduction in directly modulated diode lasers, and optical pulse manipulation. A dynamical dispersion compensation mechanism can be implemented in a fiber communication system based on such a nonlinearly chirped fiber grating.