Abstract: An optical communication system uses a radio frequency (RF) signal for communicating an analog communication signal. It comprises an optical transmitter and receiver. The transmitter generates a reference light beam, generates a shifted light beam that is shifted in frequency by the RF frequency, and responds to the analog communication signal and produces a communication light beam having a phase modulation corresponding to the analog communication signal.

Abstract: An optical communication system uses a radio frequency (RF) signal for communicating an analog communication signal. It comprises an optical transmitter and receiver. The optical transmitter comprises means for generating a first reference light beam, and means responsive to the analog communication signal to produce a communication light beam having phase modulation corresponding to the analog communication signal.

Abstract: An optical communication system, using a radio frequency (RF) signal for communicating an analog communication signal, includes an optical transmitter and an optical receiver. The optical transmitter generates a reference light beam, generates a phase modulated communication light beam by phase modulating the reference light beam with the analog communication signal, polarizes a portion of the reference light beam and combines the polarized reference light beam and the phase modulated communication light beam.

Abstract: A high average power fiber-laser system comprises a master oscillator for generating a primary laser signal; a beam splitter array for splitting the primary laser signal into N secondary laser signals; an optical frequency shifter for shifting the frequency of the primary laser signal; a phase modulator array for providing phase compensation of the N secondary laser signals; N single-mode dual clad fiber amplifiers for amplifying the N secondary laser signals and generating an output beam; a beam sampler for sampling the wavefront of the output beam, defining an array of sampled signals; means responsive to the array of sampled signals for interferometrically combining the array of said sampled signals and the shifted primary laser signal into an array of heterodyne optical signals, each having a phase that corresponds to the state of phase of the array of sampled signals; and means responsive to the array of heterodyne optical signals for providing a plurality of feedback signals to the phase modulator array

Abstract: A dynamic optical micrometer for measuring the position of a moving object is invented. The optical micrometer includes a laser for generating an optical signal, an RF signal generator, an acousto-optic modulator that is responsive to the optical signal and the RF signal and is operative to provide a first light beam and a second light beam that is up shifted in frequency by the RF frequency, an optical interferometer that reflects the first beam off the object and interferometrically combines the reflected light beam and the second light beam into a heterodyned signal, means responsive to the heterodyned signal and operative to produce an electrical signal at the optical beat frequency corresponding to the RF and means responsive to the RF signal and the electrical signal and operative to provide a linear output signal that corresponds to the position of the object. A method for accomplishing the same is also invented.

Abstract: An optical heterodyne wavefront sensor uses a radio frequency (RF) signal for measuring an optical wavefront having a state of phase that differs throughout its aperture. It comprises a lens, optical fiber and optical frequency shifter arrangement to develop a reference optical wavefront having substantially the same phase throughout and that is shifted in frequency by an amount corresponding to the RF. A beam combiner interferometrically combines the optical wavefront and the shifted reference optical wavefront into a heterodyne optical signal at the RF frequency, each subaperture of which has a phase that corresponds to the state of phase of a like subaperture of the optical wavefront.

Abstract: A dynamic instrument measures the state of optical phase of light and provides an output signal having a magnitude that varies linearly relative to the state of optical phase of a first light beam. It comprises means for generating an optical signal, means for generating a radio frequency (RF) signal that is responsive to the optical signal and the RF signal and provides a first light beam and a second light beam, at least one of which is shifted in frequency by an amount corresponding to the RF, an optical interferometer that allows the state of optical phase of the first beam to be changed and that interferometrically combines and heterodynes the changed first light beam and the second light beam, means responsive to the heterodyne signal and operative to produce an electrical signal at the optical beat frequency corresponding to the RF, and means responsive to the RF signal and the electrical signal for providing the linear output signal.

Abstract: A technique for correcting wavefront aberrations introduced by large primary optical elements in portions of the electromagnetic spectrum. The aberrations of the primary element are first transferred to a beacon beam and this aberrated beam is interfered with a reference beam in a holographic medium. These beams are then turned off and a beam from a distant object, containing the same aberrations, is allowed to diffract from the hologram. The diffracted beam from the hologram contains the image of the distant object with aberrations removed. Use of this technique permits the construction of large optical elements inexpensively, since surface tolerances of the elements can be substantially relaxed.

Abstract: A magnetometer is provided for detecting the intensity of a present magnetic field. The magnetometer includes a sample having a known resonance frequency response. A first source is provided for applying a first oscillating magnetic field having a first frequency to the sample. A second source is provided for applying a second oscillating magnetic field having a second frequency to the sample in a direction substantially transverse to the first oscillating magnetic field. A receiver is provided for detecting a frequency response output from the sample which is dependent upon the intensity of a present magnetic field so as to measure the intensity of the present magnetic field.

Abstract: Apparatus and a related method for generating a second harmonic frequency optical output from a fundamental frequency input beam, without significant birefringence. The apparatus includes two Type II doubler crystals of equal length arranged with their corresponding axes parallel to each other, and a polarization rotator positioned between the doubler crystals, to rotate the polarization angle of a residual fundamental frequency component of an output beam from one of the crystals by 90.degree. or an odd multiple of 90.degree.. Random birefringence introduced into one of the doubler crystals is virtually canceled in the other, and the assembly of the two crystals and the polarization rotator may be angularly adjusted as needed for phase matching or tuning, without detracting from the birefringence compensation capability. The invention is also disclosed in the context of a phase conjugated master oscillator power amplifier (PC MOPA) system.

Abstract: A heterodyne pumping method and system are provided for producing gyromagnetic resonance in a sample. The system includes a unidirectional static magnetic field for polarizing the sample. A first oscillating magnetic field having a first frequency is applied to said sample in the direction of said static magnetic field. A second oscillating magnetic field having a second frequency is applied transverse to said static magnetic field. A magnetic resonance response exhibited by said sample is detected and filtered by a bandpass filter so as to eliminate any drive signal interference. First and second oscillating magnetic fields are selected having first and second frequencies that provide wideband frequency separation from the resonance frequency of the sample.

Abstract: Apparatus for multiplexing or demultiplexing multiple laser beams of different wavelength. In multiplexing, the outputs from multiple diode lasers are combined in such a manner as to produce a practically parallel set of beams for direction onto a diffraction grating. The latter component deflects each beam from its normal path by an angular amount determined from the wavelength of the incident light. The angles of incidence of the multiple beams are chosen to provide angles of diffraction that are practically identical for all wavelengths under consideration. In demultiplexing, similar apparatus includes a diffraction grating to provide angular dispersion of the multiple wavelengths, at least one lens to magnify the angular differences, and a set of detectors positioned in the paths of the dispersed beams of different wavelengths.

Abstract: Apparatus and a related method for control of the colinearity of multiple laser output beams in a wavelength-multiplexed optical communications system. Multiple lasers of different wavelengths formed into a single composite beam by means of a diffraction grating and other optical components are subject to loss in colinearity due to wavelength drift and mechanical alignment drift. The apparatus of one disclosed embodiment of the invention includes an alignment detector for the output beam and a set of tracer modulation detectors responsive to tracer modulation signals impressed on the individual laser beams. Misalignment detected in any one or more of the laser beams contained in the output beam is corrected by temperature control of the appropriate lasers.

Abstract: A laser of the type which generates linearly polarized light and including optical means for self-alignment. Among such polarized lasers are, for example, solid state lasers and particularly ruby lasers, as well as various gas lasers employing Brewster windows. The problem is solved by utilizing a corner reflector in the laser cavity which generates two parallel laser beams. In order to achieve effective laser operation the polarization determining aspect of the laser, that is the crystal axis or Brewster windows, must be so oriented with respect to the corner reflector that the laser beam in passing through the laser is so reflected by the corner reflector that the light will return through the laserable material with the same directon of polarization as that of the original laser beam generated by the laser.

Abstract: A spatial filtered Q-switched laser system is disclosed having means to prevent ionization of air in close proximity to the aperture of the spatial filter. A compound lens system having an astigmatic focus is disposed between the laser and the spatial filter for defocusing the light beam emanating from the laser in the vicinity of the aperture of the spatial filter to an intensity below that which produces ionization of air. The preferred construction of the compound lens system as viewed from the laser comprises a cylindrical lens and a pair of positive lenses.

Abstract: A multifrequency laser oscillator which generates coherent light of two closely adjacent optical frequencies in rapid succession for recording contour holograms by the double exposure technique. The two light frequencies are selected by an optical intercavity frequency selector which is rotatable to a first position to select one frequency and to a second position to select the other frequency. The described laser oscillators have a ruby lasing medium and lase at the R.sub.1 and R.sub.2 transitions of the ruby resonant fluorescence.

Abstract: Apparatus and method wherein a photographic plate is doubly exposed by pulsed laser illumination to record successive instants in the history of an object under consideration. The doubly exposed plate is then developed and the photograph or hologram is used to reproduce the object in full three-dimensional detail including subtle changes in the object in the form of interference fringes where the hologram is illuminated with continuous laser illumination.