Abstract: Various disclosed embodiments provide illustrative interferometers, optical phase locked loops, laser systems, interferometry methods, and phase locked loop methods. In illustrative embodiments, light from a laser is split into a first arm and a second arm. Light in an arm chosen from the first arm and the second arm is time delayed. The light in the first arm is split into third, fourth, and fifth arms. The light in the second arm is split into sixth, seventh, and eighth arms. Light in the seventh and eighth arms is phase shifted relative to light in the sixth arm. Light in the third, fourth, and fifth arms is combined with light in the sixth arm and phase shifted light in the seventh and eighth arms, respectively. A frequency correction signal for the laser is generated.

Abstract: Various disclosed embodiments provide illustrative interferometers, optical phase locked loops, laser systems, interferometry methods, and phase locked loop methods. In illustrative embodiments, light from a laser is split into a first arm and a second arm. Light in an arm chosen from the first arm and the second arm is time delayed. The light in the first arm is split into third, fourth, and fifth arms. The light in the second arm is split into sixth, seventh, and eighth arms. Light in the seventh and eighth arms is phase shifted relative to light in the sixth arm. Light in the third, fourth, and fifth arms is combined with light in the sixth arm and phase shifted light in the seventh and eighth arms, respectively. A frequency correction signal for the laser is generated.

Abstract: An aircraft imaging system for night and day imaging at ranges up to and in excess of 100 km with resolution far exceeding the diffraction limit. In a preferred embodiment two separate techniques are utilized on an aircraft to provide for night and day surveillance. The first technique is to provide a multi-aperture active imaging system for daylight imaging. The second technique is to provide a multi-aperture passive imaging system for day and night imaging. In preferred embodiments both techniques are utilized on the aircraft.

Abstract: A particle detection system uses a reflective optic comprising a curved surface to detect high angle scattered light generated by a particle in a liquid medium, when a laser beam is incident on the particle. When the particles transit the laser beam, light is scattered in all directions and is described by MIE scattering theory for particles about the size of the wavelength of light and larger or Rayleigh Scattering when the particles are smaller than the wavelength of light. By using the reflective optic, the scattered light can be detected over angles that are greater than normally obtainable.

Abstract: A particle detection system uses a reflective optic comprising a curved surface to detect high angle scattered light generated by a particle in a liquid medium, when a laser beam is incident on the particle. When the particles transit the laser beam, light is scattered in all directions and is described by MIE scattering theory for particles about the size of the wavelength of light and larger or Rayleigh Scattering when the particles are smaller than the wavelength of light. By using the reflective optic, the scattered light can be detected over angles that are greater than normally obtainable.

Abstract: A particle detection system uses a reflective optic comprising a curved surface to detect high angle scattered light generated by a particle in a liquid medium, when a laser beam is incident on the particle. When the particles transit the laser beam, light is scattered in all directions and is described by MIE scattering theory for particles about the size of the wavelength of light and larger or Rayleigh Scattering when the particles are smaller than the wavelength of light. By using the reflective optic, the scattered light can be detected over angles that are greater than normally obtainable.

Abstract: A particle detection system uses illumination incident at an angle to detect particles in a liquid such as water. By using illumination incident at an angle, the scattered light can be measured through a range of angles that are greater than the measured range of angles produced when the illumination is incident at a normal angle, when using the same detector. For example, the light can be measured through an angle that is twice that produced with illumination incident at a normal angle.

Abstract: A large fiber optic switch system with a free-space optical interconnection configuration. The switch system comprises a plurality of individual switch units, each individual switch unit having a plurality of electronic multi-switch switches each multi-switch switch being re-configurable upon command of a computer processor and having a plurality of electronic input ports and electronics output ports. A first portion of these input ports and a first portion of these output ports are connected directly or indirectly to incoming and outgoing communication lines. A second portion of the output ports is connected to an electronic driver unit that drives an optical emitter array. Each emitter in the emitter array produces a light beam for carrying an optical communication signal.

Abstract: A large fiber optic switch system with a free-space optical interconnection configuration. The switch system comprises a plurality of individual switch units, each individual switch unit having a plurality of electronic multi-switch switches each multi-switch switch being re-configurable upon command of a computer processor and having a plurality of electronic input ports and electronics output ports. A first portion of these input ports and a first portion of these output ports are connected directly or indirectly to incoming and outgoing communication lines. A second portion of the output ports is connected to an electronic driver unit that drives an optical emitter array. Each emitter in the emitter array produces a light beam for carrying an optical communication signal.

Abstract: A thin diamond electron beam amplifier. The illumination side of a thin diamond is illuminated by a seed electron beam creating electron-hole pairs in the diamond. A voltage potential provides an electric field between the illumination side of the diamond and an acceleration grid opposite the emission side of the diamond. Electrons released in the diamond are accelerated through the emission side of the diamond toward the acceleration grid creating an amplified electron beam. Preferred embodiments of the present invention are useful to provide flat panel displays and replacements for thermionic cathodes, cathode ray tubes, fast photodetectors and image intensifiers.

Abstract: This invention provides an acoustic imaging device which utilizes scattered acoustic wave information to produce an image. The system consists of an array of acoustic transducers which at least partially encircle a medium to be imaged. The medium is sequentially insonified by each transducer with an acoustic signal comprised of at least one discrete frequency. The acoustic signal scatters from the medium and is detected by the remaining transducers. A data set representing the phase and amplitude of each discrete frequency at each transducer is acquired and used by a computer to calculate an image of the medium. Images acquired and calculated at each identifiable discrete frequency are combined in various ways in order to improve the quality of the final image of the medium.

Abstract: This invention provides an acoustic imaging device in which a large number of transducers are spaced less than a half acoustic wavelength apart on a circle surrounding an object to be imaged. A signal generator generates discrete acoustic frequencies in the range of 100 kHz to 1.5 MHz. Multiplexer systems are provided to permit each transducer, one at a time, to broadcast a signal while the broadcast signal is detected by the other transducers. Electronic equipment records the detected signal and from the recorded information phase and amplitude data is calculated with respect to each transducer location. A computer programmed with an algorithm computes images of slices through the object using the phase and amplitude data. We utilize single frequency, steady-state acoustic signals which enables the accurate determination of the phase and amplitude of the acoustic signals at each receiver transducer.

Abstract: A device and method for producing an image of a fluid moving through a medium. An acoustic wave insonifies the medium to produce Doppler shifted scattering from randomly located scatterers in the moving fluid. At least eight channels of acoustic detectors detect signals reflected from the medium and the amplitudes of the scattered signal is determined at each channel for at least one Doppler shifted frequency. Time averaged channel-to-channel amplitude correlations are produced using the Doppler shifted amplitude data from which the image of the moving fluid is calculated.

Abstract: An acoustic imaging device is disclosed which utilizes mathematical inversion of scattered acoustic wave information to produce an image. A preferred embodiment of the device consists of a ring of acoustic transducers which encircle a medium to be imaged. The medium is sequentially insonified by each transducer with subsequent reception of the scattered waves by the remaining transducers. Explicit mathematical inversion of the scattered wave data using a remap algorithm results in a two-dimensional map of the scattering potential of the medium. Sound speed and density maps can be obtained from a map of the scattering potential. This device is utilizable for imaging of human tissue in vivo and in vitro, and for nondestructive evaluation of materials.

Abstract: A camera system in which microwave radiation from objects in a field-of-view is collected by an antenna having a beam direction which is a function of the beam frequency. The collected radiation is analyzed to produce an image of the objects in the field-of-view. In a simple embodiment of the invention a one dimensional image is produced. This one dimensional image can be converted to a two dimensional image by rotating the camera system or mounting the camera on a moving platform. In a preferred embodiment of the present invention the microwave radiation collected by the antenna is converted into electronic acoustic signals which sets up a diffraction pattern in a Bragg cell to diffract a laser beam which is focused on a television camera to produce one dimensional image of the field-of-view. The antenna can be scanned to produce a two dimensional image. In another preferred embodiment an array of antennas and a multi-channel Bragg cell is used to produce a two dimensional real time image.

Abstract: A compensating beamformer which requires orders of magnitude fewer calculations that prior art methods. A compensating beamformer is provided which comprises a plurality of sensing elements and a plurality of analog-to-digital converters, for converting incoming analog signals to digital form. Digital signals from at least four such elements are used to compute phase angle information which is combined to form a matrix of input data in the frequency domain. An unweighted steering vector is determined to sample data from the target direction. A corrector matrix is calculated based on input data from sensing elements. That corrector matrix along with its inverse, which is determined recursively, is used in combination with the unweighted steering vector to determine an optimal steering vector. The input data in the frequency domain are then multiplied by the optimal steering vector to obtain signals in the directions of interest.

Abstract: A telescope with a spherical primary mirror and a movable secondary optical element which is positioned at various locations near the focal plane of the primary mirror and directs a portion of the focused radiation to a coude optics device at the center of curvature of the primary mirror. The coude optics device reflects the focused radiation to a detector. In a preferred embodiment of this invention a field of several degrees can be scanned very rapidly while viewing much smaller object fields.

Abstract: A wavefront, such as from a laser, is sampled, preferably at a beam splitter to break off only a fraction of the total light energy. The sampled beam is adjusted and sized--either by expansion or contraction at a conventional telescope--and thereafter sent through paired crossed Ronchi gratings and onto a CCD camera located at the first wave distance of constructive interference from the crossed Ronchi gratings. The crossed Ronchi gratings--in the order of 200 lines per inch and preferably with 200 equally spaced gaps per inch--project an array of square spots onto the focus of the CCD camera. The image of the array of square spots at the CCD camera is frozen via a frame grabber and digitized in a conventional format. The digitized image is played through a disclosed computer program to locate the spots. Thereafter, the located spots are compared to a standard spots.