Abstract: In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including 3He gas, wherein if 4He gas is also present in the buffer gas, the ratio of the concentration of the 3He gas to the 4He gas is greater than 1.37×10?6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including 3He gas, wherein if 4He gas is also present in the buffer gas, the ratio of the concentration of the 3He gas to the 4He gas is greater than 1.37×10?6. Other embodiments are also disclosed.

Abstract: In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including 3He gas, wherein if 4He gas is also present in the buffer gas, the ratio of the concentration of the 3He gas to the 4He gas is greater than 1.37×10?6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including 3He gas, wherein if 4He gas is also present in the buffer gas, the ratio of the concentration of the 3He gas to the 4He gas is greater than 1.37×10?6. Other embodiments are also disclosed.

Abstract: A beacon beam is transmitted from a receiver to a transmitter. The transmitter generates and transmits a conjugate beacon beam back to the receiver, where it is interfered with a local oscillator beam to form a hologram. The hologram is used to configure a spatial light modulator as a diffraction grating. A conjugate communications laser beam containing information is subsequently transmitted to the receiver. The diffraction grating deflects the conjugate communications beam to a fixed and known direction, whereupon it is directed through a spatial filter. Since the direction of the conjugate communications beam is fixed and known, the diameter of the filter aperture can be minimized to accept the communications beam while rejecting almost all of the background light. A high-speed detector directly detects the filtered conjugate communications beam. The detector output is transmitted to a demodulator that extracts the information carried by the communications beam.

Abstract: A new differential technique for forming optical images using a synthetic aperture is introduced. This differential technique utilizes a single aperture to obtain unique (N) phases that can be processed to produce a synthetic aperture image at points along a trajectory. This is accomplished by dividing the aperture into two equal “subapertures”, each having a width that is less than the actual aperture, along the direction of flight. As the platform flies along a given trajectory, a source illuminates objects and the two subapertures are configured to collect return signals. The techniques of the invention is designed to cancel common-mode errors, trajectory deviations from a straight line, and laser phase noise to provide the set of resultant (N) phases that can produce an image having a spatial resolution corresponding to a synthetic aperture.

Abstract: Laser material is pumped and its stored energy is extracted in a heat capacity laser mode at a high duty factor. When the laser material reaches a maximum temperature, it is removed from the lasing region and a subsequent volume of laser material is positioned into the lasing region to repeat the lasing process. The heated laser material is cooled passively or actively outside the lasing region.

Abstract: A new differential technique for forming optical images using a synthetic aperture is introduced. This differential technique utilizes a single aperture to obtain unique (N) phases that can be processed to produce a synthetic aperture image at points along a trajectory. This is accomplished by dividing the aperture into two equal “subapertures”, each having a width that is less than the actual aperture, along the direction of flight. As the platform flies along a given trajectory, a source illuminates objects and the two subapertures are configured to collect return signals. The techniques of the invention is designed to cancel common-mode errors, trajectory deviations from a straight line, and laser phase noise to provide the set of resultant (N) phases that can produce an image having a spatial resolution corresponding to a synthetic aperture.

Abstract: A MEMS SLM and an electrostatic actuator associated with a pixel in an SLM. The actuator has three electrodes: a lower electrode; an upper electrode fixed with respect to the lower electrode; and a center electrode suspended and actuable between the upper and lower electrodes. The center electrode is capable of resiliently-biasing to restore the center electrode to a non-actuated first equilibrium position, and a mirror is operably connected to the center electrode. A first voltage source provides a first bias voltage across the lower and center electrodes and a second voltage source provides a second bias voltage across the upper and center electrodes, with the first and second bias voltages determining the non-actuated first equilibrium position of the center electrode.

Abstract: A MEMS SLM and an electrostatic actuator associated with a pixel in an SLM. The actuator has three electrodes: a lower electrode; an upper electrode fixed with respect to the lower electrode; and a center electrode suspended and actuable between the upper and lower electrodes. The center electrode is capable of resiliently-biasing to restore the center electrode to a non-actuated first equilibrium position, and a mirror is operably connected to the center electrode. A first voltage source provides a first bias voltage across the lower and center electrodes and a second voltage source provides a second bias voltage across the upper and center electrodes, with the first and second bias voltages determining the non-actuated first equilibrium position of the center electrode.

Abstract: The amplitude of an input laser beam is modulated by a two-dimensional array of Michelson interferometers comprised of a phase spatial light modulator, a mirror and a 50/50 light beamsplitter. The array of Michelson interferometers is calibrated by adjusting the path length of one of the interferometer arms. The calibration is maintained with the aid of feedback. The amplitude-modulated beam is then directed successively through a field imaging telescope, a polarization beamsplitter, and a quarter-wave plate before impinging a second phase spatial light modulator. The second spatial light modulator is adjusted to apply the desired phase profile. The beam, which at this point has the desired amplitude and phase profiles, is then again directed through the quarter-wave plate and subsequently reflected off of the polarization beamsplitter, out of the apparatus, and into free space.

Abstract: The amplitude of an input laser beam is modulated by a two-dimensional array of Michelson interferometers comprised of a phase spatial light modulator, a mirror and a 50/50 light beamsplitter. The array of Michelson interferometers is calibrated by adjusting the path length of one of the interferometer arms. The calibration is maintained with the aid of feedback. The amplitude-modulated beam is then directed successively through a field imaging telescope, a polarization beamsplitter, and a quarter-wave plate before impinging a second phase spatial light modulator. The second spatial light modulator is adjusted to apply the desired phase profile. The beam, which at this point has the desired amplitude and phase profiles, is then again directed through the quarter-wave plate and subsequently reflected off of the polarization beamsplitter, out of the apparatus, and into free space.

Abstract: Laser material is pumped and its stored energy is extracted in a heat capacity laser mode at a high duty factor. When the laser material reaches a maximum temperature, it is removed from the lasing region and a subsequent volume of laser material is positioned into the lasing region to repeat the lasing process. The heated laser material is cooled passively or actively outside the lasing region.

Abstract: A beacon beam is transmitted from a receiver to a transmitter. The transmitter generates and transmits a conjugate beacon beam back to the receiver, where it is interfered with a local oscillator beam to form a hologram. The hologram is used to configure a spatial light modulator as a diffraction grating. A conjugate communications laser beam containing information is subsequently transmitted to the receiver. The diffraction grating deflects the conjugate communications beam to a fixed and known direction, whereupon it is directed through a spatial filter.

Abstract: The present invention relates to a laser pointing and tracking system which forms and maintains a small laser spot size at a selected aimpoint on a target and compensates for optical distortion in the intervening media. The invention comprises an illumination laser for directing a first wide divergence beam of short-pulse laser radiation toward a stationary or moving target. The target reflects a portion of the incident beam as return radiation which is interfered with a properly-timed short-pulse reference beam on an electronic radiation detector array. The detector array signals are processed to produce an electronic hologram which is imposed as a phase pattern on a spatial light modulator. A laser reads out the hologram to direct a beam of radiation at the target. Multiple sequential illumination and hologram formation/readout steps produce a small spot size at the selected aimpoint. The small spot is maintained at the aimpoint during the duration of an engagement by repeating the above steps.

Abstract: A light modulator for both intensity and phase modulating coherent light on a pixel-by-pixel basis includes a modulating material responsive to an electric potential for modulating the intensity of coherent light passing through the modulating material, and electrodes for applying an electric potential across the modulating material on a pixel-by-pixel basis. The coherent light associated with a first set of pixels has a different optical path length through the modulating material than does the coherent light associated with a second set of pixels. The modulating material is a liquid crystal material. The electrodes include a set of first reflective pixel electrodes embedded in the liquid crystal material, the first reflective pixel electrodes having a first thickness, and a set of second reflective pixel electrodes embedded in the liquid crystal material, the second reflective pixel electrodes having a second thickness.

Abstract: A holographic laser target acquisition and tracking system with aberration compensation including a detector array, a master-oscillator (MO), a hologram processor, a spatial light modulator (SLM) and a slave oscillator which is referred to as a Holographic Interactive Tracker system. The operation of the system consists of two steps. In step one, an acquisition step, a diverging laser beam (acquisition beam) from the laser oscillator is transmitted to a target 38. The beam divergence is typically much larger than the target angular extent. A fraction of the diverging energy intercepted by the target is returned, as a beam or as diffuse radiation, and collected by a receiver optic. This target return is interfered with a master oscillator beam from the MO on the electronic detector array, thereby forming an electro-optic hologram. The detector array is read out pixel by pixel and applied to the hologram processor which enhances the hologram by subtracting out the d.c. component.

Abstract: An optical frequency conversion apparatus includes at least one resonator (10) having an optical path defined by a plurality of mirrors (M1, M2). A nonlinear conversion medium (10a) is disposed within the optical path of the resonator, the nonlinear conversion medium receiving optical radiation at a first frequency and outputting optical radiation at a second frequency that is a multiple of the first frequency. One of the plurality of mirrors is an input mirror (M1) for coupling into the resonator a pulse of radiation having the first frequency, and one of the mirrors is an output mirror (M2) for out-coupling a pulse of radiation having a frequency that is a multiple of the first frequency.

Abstract: A highly efficient pumping configuration for a solid state laser uses a diode bar pumping source producing optical energy coherent along an axis normal to the plane of the diode junctions. Pump energy is nearly collimated by a cylindrical optical fiber and applied through a minimum width injection port to a low absorption solid state laser rod in a highly reflective optical cavity including a cylindrical sleeve forming a coolant chamber around the laser rod. The nearly collimated energy is focussed to a minimum width in the plane of the injection port in order to minimize the loss of energy from the optical chamber by leakage out through the port. The laser rod is substantially evenly illuminated by the entire energy entering the cavity on the first pass. Optical energy not absorbed during illumination through is reflected within the cavity until substantially absorbed by the solid state laser rod.

Abstract: A spatial light modulator comprises a plate of non-ferroelectric PLZT ceramic. An array of pixels is formed by depositing a reflecting coating in the desired array on one side of the plate. A longitudinal electric field is applied so that the light entering the plate from the side opposite the reflecting coating experiences a polarization-independent refractive index change when the electric field is applied as it propagates parallel to the electric field. The required voltages may be decreased when a partially reflecting coating is deposited on the side opposite the reflecting coating. Grooves in the plate effectively isolate the pixels from electrical and mechanical crosstalk.

Abstract: A method and apparatus for transferring energy to a gas by means of a glow discharge. A transmission line is charged to a voltage of approximately twice that of the steady-state voltage of the glow discharge. A prepulse voltage source, having a higher voltage sufficient to initiate the glow discharge, is first connected to the discharge electrodes. After the discharge is initiated by the prepulse, the transmission line is connected and transfers its energy to the discharge. In a second embodiment, the transmission line is replaced by a capacitor.

Abstract: A pair of electrodes for producing a very uniform electric field within a predetermined region. The electrodes have a special theoretically-derived shape which inherently terminates the electrodes just outside the predetermined region, thereby overcoming any need to empirically truncate the design to achieve compactness and low inductance. In contrast to conventional truncated designs, the performance of electrodes shaped according to the present invention is analytically predictable, thereby minimizing the need for time-consuming experimentation.