Rockwell International Corporation

The Boeing Company

Oplink Communications, Inc.

Ian C McMichael

Mohsen Khoshnevisan

Pochi A Yeh

Scott Patrick Campbell

Manouchehr E Motamedi

William R Christian

Mark J Rosker

Mohen Khoshnevisan

A method for controlling the frequency dependence of insertion loss in an etalon-lens-fiber (ELF) optical assembly comprises defining target frequencies and insertion loss objectives therefor and adjusting the optical path length between pairs of the etalon, lens and fiber components until insertion loss objectives are achieved. Insertion loss objectives include insertion loss and insertion loss ripple objectives. The method allows for control of the frequency dependence of insertion loss and insertion loss ripple without introducing additional components, such as spectral filters, into the system.

Method for controlling the frequency dependence of insertion loss in an optical assembly

An acousto-micro-optic deflector (AMOD) is provided. This device uses a special combination of an acousto-optic deflector (AOD) and a micro-optic deflector (MOD) to provide agile gimballess beam steering over large angles. The combination is driven such that the entire field of regard of the device is accessible, and continuous contact with the target point is maintained.

Acousto-micro-optic deflector

A light curtain having linearly arranged pairs of light transmitting and receiving which may be placed on opposing sides of a zone to be protected. The light curtain provides uniform sensitivity across the region to be protected as the light transmitters emit a light beam which begins as an omnidirectional point source which is truncated and refocused by an optical lense. Predetermined portions of the beam are blocked to assure uniform intensity across the width of the transmitter.

Uniform sensitivity light curtain

A pulsed diode ring laser gyroscope and method of modulation are provided to greatly reduce the occurrence of frequency locking in optical gyroscopes at low rotational rates. One or two optical diodes serve as optical amplifiers for a pair of counterpropagating optical pulses circulating in an optical ring resonator. The amplifiers are driven twice each round trip (once for each pulse) using pulses much shorter than the round trip time. The short optical pulses overlap in regions of the resonator generally isolated from light scattering elements. The pulses are produced by gain switching the optical amplifiers with an electrical current pulse train having a fundamental period synchronous with the optical round trip time in the resonator cavity. With this modulation scheme, the diodes can be thought of as gates that open twice each round trip-once for each of the counterpropagating pulses. During each on time, the diodes amplify only a clockwise or counterclockwise pulse. Backscattered light from any optical element, which is not coincident with either of the pulses, is absorbed by the amplifiers.

Pulsed diode ring laser gyroscope

A three-dimensional object is imaged by providing a coherent beam of light with a periodic variation in frequency and dividing the beam into a probe beam and a pump beam. The probe beam is directed toward the object, such that the frequency profile of the probe beam after reflection from the object is determined by the depth profile of the object. The pump beam and the reflected probe beam are directed into a nonlinear medium, such that two-wave mixing between the beams occurs in the medium, the two-wave mixing process causing the frequency profile of the probe beam to be converted to an intensity profile. The method may be further refined by adjusting the optical path length of the pump beam in order to adjust the accuracy range of the depth profile which is imaged. In addition, the reflected intensity profile of the object can be obtained from the reflected probe beam prior to the mixing of the probe beam and the pump beam and subtracted from the converted intensity profile to correct the converted intensity profile for variations in the surface reflectivity of the object. A nonlinear optical ranging imager for imaging a three-dimensional object includes a source of coherent light with a periodic variation in frequency and a beam splitter for dividing the source into a pump beam and a probe beam directed at the object, such that a frequency profile of the probe beam after reflection from the object is determined by the depth profile of the object. A nonlinear optical medium receives the reflected probe beam and the pump beam, such that two-wave mixing between the two beams occurs within the medium, the two-wave mixing process causing the frequency profile of the probe beam to be converted to an intensity profile.

Nonlinear optical ranging imager

An apparatus for subtracting the amplitude of a first optical image on a first beam from the amplitude of a second optical image on a second beam includes a first beam splitter to divide the first beam into a first transmitted beam and a first reflected beam and to divide the second beam into a second transmitted beam and a second reflected beam. The first transmitted beam and the second reflected beam combine as a first mixed beam, while the first reflected beam and the second transmitted beam combine as a second mixed beam. A pinhole removes spatial information from the second mixed beam. The first and second mixed beams interfere within a nonlinear medium to create a composite hologram. A coherent reference beam directed at the nonlinear medium reads the interference pattern, so that the difference between the first and second images is superimposed on the reference beam emerging from the nonlinear medium. A second nonlinear medium may be used to retroreflect one of the mixed beams toward the nonlinear medium as the reference beam, in which case the pinhole is not required.

Real-time optical image subtraction

An optical fiber rotation sensor includes a source of coherent light and a first polarizing beam splitter for transmitting a first component of the coherent light having a first polarization direction and reflecting a second component of the coherent light having a second polarization direction orthogonal to the first polarization direction. A coiled multimode optical fiber is coupled to the first beam splitter with the first and second components propagating in the fiber in opposite directions. A polarizer transmits a linearly polarized third component containing equal contributions from the first and second components. A half-wave plate rotates the polarization of the third component by 45.degree.. A self-pumped phase conjugating element reflects a phase-conjugated fourth component such that the fourth component retraverses the half-wave plate and the polarizer, then is divided by the first polarizing beam splitter into fifth and sixth components propagating in the fiber in opposite directions. A second polarizing beam splitter transmits a seventh component having the first polarization direction and reflects an eighth component having the second polarization direction. A first detector measures the power of the seventh component, while a second detector measures the power of the eighth component, the difference being related to the angular motion of the rotation sensor.

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Port Hueneme, CA, United States of America

Ian C McMichael