Abstract: A hybrid beam combining system or method combines a plurality of coherent and incoherent light beams into a composite high power diffraction limited beam. N oscillators each transmit light at one of N different wavelengths and each wavelength is split into M constituent beams. M beams in each of N groups are phase locked by a phase modulator using phase correction signals. The phase locked beams are amplified and coupled into an M×N fiber array. Beams emerging from the array are collimated and incident on a diffractive optical element operating as a beam combiner combining the M outputs at each N wavelength into a single beam. The N single beams are incident and spectrally combined on a grating which outputs a composite beam at a nominal 100% fill factor. A low power sample beam, taken from the N beams emerging from the diffractive optical element, is measured for phase deviations from which the phase correction signals are derived and fed back to the phase modulators.

Abstract: A method and related apparatus for sensing selected emotions or physical conditions in a human subject. The technique employs a two-dimensional camera to generate a facial image of a human subject. Then, an image processing module scans the image to locate the face position and extent, and then scans for selected critical areas of the face. The size and activity of the selected critical areas are monitored by comparing sequential image frames of the subject's face, and the areas are tracked to compensate for possible movements of the subject. The sensed parameters of the selected critical areas are compared with those stored in a database that associates activities of the critical areas with various emotional and physical conditions of the subject, and a report or assessment of the subject is generated.

Abstract: A system or method coherently combines a large number of light beams at a single wavelength in multiple stages to form a high-power diffraction limited output beam. A two-stage system, or method based thereon, includes a master oscillator transmitting a light beam to a first phase modulation stage, which splits the beam into N beams and locks beam phases using phase correction signals from a first feedback loop. A second phase modulation stage splits each N beam into M beams and locks the phases of M beams in each N group using phase correction signals from a second feedback loop. A two-dimensional fiber array directs M×N beams to a first diffractive optical element combining the beams into N coherent beams of M beams each, and phase correction signals for the second stage are derived from a sample extracted from the N coherent beams.

Abstract: A system and method for combining plural low power light beams into a coherent high power light beam by means of a diffractive optical element operating as both a beam combiner and beam sampler. An oscillation source transmits a master signal that is split into plural beams propagating at a common wavelength. Each beam is phase locked by a corresponding phase modulator according to a phase correction signal. The beams are directed through a fiber array to the diffractive optical element to allow efficient coherent combination of the beams at a desired diffraction order. The diffractive optical element includes a periodic sampling grating for diffracting a low power sample beam representative of the combined beam. A phase detection stage detects phases of constituent beams in the sample beam from which the phase correction signals are derived and fed back to the phase modulators.

Abstract: A hybrid beam combining system or method combines a plurality of coherent and incoherent light beams into a composite high power diffraction limited beam. N oscillators each transmit light at one of N different wavelengths and each wavelength is split into M constituent beams. M beams in each of N groups are phase locked by a phase modulator using phase correction signals. The phase locked beams are amplified and coupled into an M×N fiber array. Beams emerging from the array are collimated and incident on a diffractive optical element operating as a beam combiner combining the M outputs at each N wavelength into a single beam. The N single beams are incident and spectrally combined on a grating which outputs a composite beam at a nominal 100% fill factor. A low power sample beam, taken from the N beams emerging from the diffractive optical element, is measured for phase deviations from which the phase correction signals are derived and fed back to the phase modulators.

Abstract: A system or method coherently combines a large number of light beams at a single wavelength in multiple stages to form a high-power diffraction limited output beam. A two-stage system, or method based thereon, includes a master oscillator transmitting a light beam to a first phase modulation stage, which splits the beam into N beams and locks beam phases using phase correction signals from a first feedback loop. A second phase modulation stage splits each N beam into M beams and locks the phases of M beams in each N group using phase correction signals from a second feedback loop. A two-dimensional fiber array directs M×N beams to a first diffractive optical element combining the beams into N coherent beams of M beams each, and phase correction signals for the second stage are derived from a sample extracted from the N coherent beams.

Abstract: A fiber optic phased array and control method are provided for controllably adjusting the phase and amplitude of the optical signals emitted by a plurality of fiber optic amplifiers to compensate for atmospheric turbulence. The fiber optic phased array also includes a sensor assembly for detecting: (i) the phase of the optical signals that are emitted by the fiber optic amplifiers, and (ii) both the phase and the amplitude of the optical signals that have been reflected by the target. The fiber optic phased array also includes phase modulators and a gain adjustment mechanism for altering the phase and the amplitude of the optical signals propagating along the fiber optic amplifiers to compensate for modifications in the phase and amplitude that will be introduced by atmospheric turbulence. Among other things, the amplitude control of the optical signals is not adversely effected by intensity nulls in the reflected wavefront.

Abstract: A system and method for combining plural low power light beams into a coherent high power light beam. Optical amplifiers transmit a plurality of light beams propagating at a common wavelength through an array of optical fiber emitters. Each constituent beam is emitted from the array at a different propagation angle, collimated, and incident on a diffractive optical element operating as a beam combiner such that incident beams when properly phased and located are combined into a coherent beam at a desired diffraction order. A beam splitter or a periodic sampling grating on the diffractive optical element directs a low power sample beam to a spatial filter passing resonant mode output back to the optical amplifiers in a ring laser configuration thereby passively synchronizing phases of the constituent beams to maximize combination efficiency of the coherent beam.

Abstract: A pulsed coherent fiber array laser system that includes a beam generating sub-system that provides a signal pulse beam having pulses of the desired duration that is split into several fiber channels. Optical leakage between the pulses in each split beam is measured and locked to a reference beam by a phase sensing circuit and phase adjusters so that the phase of each fiber pulsed beam is aligned with the phase of the reference beam. A pulse clipper or filter is employed to remove the pulses in the fiber beams so that they do not saturate the phase sensing circuit. The beam generating sub-system can employ any suitable combination of devices to generate the signal beam and the reference beam, including continuous wave master oscillators, amplitude modulators, frequency shifters, injection seed oscillators, Q-switched lasers, reference oscillators, frequency lockers, wavelength division multiplexers, time gated switches, etc.

Abstract: An optical fiber amplifier array and related method, in which high beam quality is achieved by varying the frequency of an input signal applied to all of the fiber amplifiers, to locate a frequency at which the amplifiers produce nearly coherent optical outputs. In spite of statistical variations in length and other factors among the fibers, there are frequencies at which the amplifiers produce nearly coherent outputs. In the control system of the invention, the input signal frequency is scanned across a selected narrow range and the beam quality is monitored by measuring on-axis far-field output beam intensity. The frequency is scanned until the beam intensity exceeds a selected threshold, and then the frequency is held constant until the beam intensity falls below a second selected threshold.

Abstract: A laser array architecture scalable to very high powers by closely stacking fiber amplifiers, but in which the output wavelength is selectable to be in the visible or ultraviolet region, without being restricted by the wavelengths usually inherent in the choice of fiber materials. A pump signal at a fundamental frequency is amplified in the fiber amplifier array and input to an array of nonlinear crystals that function as harmonic generators, producing an output array at a desired harmonic of the fundamental frequency. A phase detection and correction system maintains the array of outputs in phase coherency, resulting in a high power output with high beam quality, at the desired frequency. The array of nonlinear crystals may a single array to produce a second harmonic output frequency, or a combination of multiple cascaded arrays configured to produce a selected higher order harmonic frequency.

Abstract: A hybrid laser source including a solid state laser driven by an array of fiber laser amplifiers, the inputs of which are controllable in phase and polarization, to compensate for distortions that arise in the solid state laser, or to achieve desired output beam properties relating to direction or focus. The output beam is sampled and compared with a reference beam to obtain phase and polarization difference signals across the output beam cross section, at spatial positions corresponding with the positions of the fiber laser amplifiers providing input to the solid state laser. Therefore, phase and polarization properties of the output beam may be independently controlled by predistortion of these properties in the fiber laser amplifier inputs.

Abstract: A laser array architecture scalable to very high powers by fiber amplifiers, but in which the output wavelength is selectable, and not restricted by the wavelengths usually inherent in the choice of fiber materials. A pump beam at a first frequency is amplified in the fiber amplifier array and is mixed with a secondary beam at a second frequency to yield a frequency difference signal from each of an array of optical parametric amplifiers. A phase detection and correction system maintains the array of outputs from the amplifiers in phase coherency, resulting in a high power output at the desired wavelength. A degenerate form of the architecture is disclosed in an alternate embodiment, and a third embodiment employs dual wavelength fiber amplifiers to obtain an output at a desired difference frequency.

Abstract: A solid-state laser system includes a solid-state laser having a laser gain medium and at least one pumping diode. The system also includes a thermal management system capable of placing a coolant in thermal communication with the solid-state laser such that the coolant can carry heat away from the solid-state laser. The thermal management system is then capable of rejecting the heat carried away by the coolant to a fluid at an ambient temperature, where the coolant can be at a temperature between 40° C. and 80° C. when the thermal management system rejects the heat. Advantageously, the thermal management system of the present invention can include reject the heat to a fluid comprising, for example, air or water. As such, the thermal management system does not require separate cooling of the fluid carrying the heat away from the coolant.

Abstract: Methods and apparatus are provided for modifying a free electron laser (FEL) to produce a non-diverging laser beam. A relativistic electron beam is converted to a Bessel beam in an FEL resonator with conical end mirrors, and the Bessel beam is coupled to the optical field within the laser resonator. The resultant laser beam is propagated with minimal divergence, and is wave corrected at the resonator output to produce a uniform intensity circular beam. The laser beam can be of smaller diameter than that of a conventional resonator due to its diffractionless propagation, which enables the magnetic structure gap within the resonator to be smaller, thus producing a higher optical gain.

Abstract: A laser diode array is formed on a substrate (310) in which a number of parallel grooves (312) are formed. A metal layer (410) is formed on the grooves (312). Laser diode bars (314) are fitted in alternate grooves, and every other groove is left vacant to serve as a cooling channel (316). The array is immersion cooled in a housing (210). Liquid coolant is circulated through the housing (210) and through a heat exchanger (216). The liquid coolant flows over a major surface of the substrate (310) and through the cooling channels (316). Thus, heat is removed by circulating fluid from three sides of the laser diode bars (314). Such high-performance cooling permits the laser diode array to have a greater power density.

Abstract: A micro-doppler ladar comprising a tunable laser to identify an unknown constituent of a gaseous cloud or region at a safe distance from the cloud or region. The tunable laser produces a laser beam tunable over a range of different frequencies. Each frequency produces a different vibrational response in the constituent in the gaseous cloud when the cloud or region is illuminated by the laser beam. A micro-doppler ladar system then interprets a back scattered beam to determine the induced vibrations. The determined induced vibrations can then be compared to known vibrations stored in a look-up table to identify the specific constituent(s) in the cloud or region.

Abstract: Methods and apparatus are provided for detecting a target substance in an atmospheric target area. The target area is illuminated with a laser beam to produce back-scatter light from substances within the target area. The back-scatter light is combined with a sample of the target substance within a hollow core fiber that has been pumped with a laser spectrum identical to the illuminating bean. If a back-scatter spectrum matches the pumped sample in the hollow core fiber, stimulated Raman scattering emissions can occur, which provide optical gain for the matching spectrum. A detector analyzes the amplified matching spectrum to identify the target substance. The disclosed apparatus may be expanded to detect multiple target substances simultaneously by using hollow core fibers containing different target samples.

Abstract: An optical fiber amplifier has an anisotropic numerical aperture to optimally couple pump energy into the pump core of a dual-clad fiber. The optical fiber consists of a dual-clad fiber having a longitudinally extending inner core, an outer core surrounding the inner core, and a cladding layer at least partially surrounding the outer core. The outer core is capable of transmitting pump energy to thereby amplify signals propagating through the inner core. Further, the outer core is capable of accepting pump energy within a first range of acceptance angles in a first direction and within a second range of acceptance angles in a second direction that is perpendicular to the first direction. The outer core and the cladding layer are structured such that a numerical aperture of the fiber amplifier in the first direction is different than the numerical aperture of the fiber amplifier in the second direction.

Abstract: A direct diode laser system includes N laser head assemblies (LHAs) generating N output beams, N optical fibers receiving respective N output beams and generating N received output beams, and a torch head recollimating and focusing the N received output beams onto a single spot. Preferably, each of the laser head assemblies of the direct diode laser system includes M modules generating M laser beams, wherein each of the M laser beams has a corresponding single wavelength of light. M-1 dichroic filters, wherein each of the M-1 dichroic filter transmits a corresponding one of the M laser beams and reflects all other wavelengths, and a fiber coupling device collecting the M laser beams to produce a respective one of the N output beams. In an exemplary case, the M-1 dichroic filters function as band pass filters. A method of generating a high fluence, high power laser beam is also described.