Abstract: A method of defense against optically guided missiles, said method comprising the steps of: mounting a single-ended laser adjacent the area to be protected emitting electromagnetic radiation at a frequency within the sensitive frequency range of said guided missile, directing said radiation toward an area within which said radiation may be reflected by components of said missile, causing lasing operation of said laser in response to reflection of said radiation by components of said missile, and modulating the output of said laser in response to said lasing operation for misdirecting said guided missile.

Abstract: Methods of processing seismic data to remove unwanted noise from meaningful reflection signals are provided for. The seismic data is transformed from the offset-time domain to the time-slowness domain using a high resolution Radon transformation. That is, the Radon transformation is performed according to an index j of the slowness set and a sampling variable ?p; wherein j = p max - p min + 1 ? ? ? µ ? ? ? sec ? / ? m ? ? ? ? p , ?p is from about 0.5 to about 4.0 ?sec/m, pmax is a predetermined maximum slowness, and pmin is a predetermined minimum slowness. A corrective filter is then applied to enhance the primary reflection signal content of the data and to eliminate unwanted noise events. After filtering, the enhanced signal content is inverse transformed from the time-slowness domain back to the offset-time domain using an inverse Radon transformation.

Abstract: A Raman amplifier for an optical transmission system. A light source unit generates pumping light to amplify wavelength-multiplexed signal light having a plurality of wavelengths including a wavelength band of the signal light. A transmission path propagates the signal light and the pumping light and amplifies the signal light. A pumping light supplying unit supplies the pumping light to the transmission path. A filter narrows a spread of a spectrum of the pumping light within the wavelength band of the signal light and outputs it to the pumping light supplying unit. The present invention increases transmission capacity while suppressing degradation of the transmission characteristic due to crosstalk.

Abstract: The present invention is a method of determining formation horizontal shear wave velocity, formation transverse isotropy and an effective logging tool modulus. The method comprises determining an effective logging tool modulus by modeling the logging tool as a fluid filled cylindrical shell. Measured Stoneley-wave slowness values are acquired for a formation. A horizontal formation shear wave velocity, Vsh, is calculated as a function of the measured Stoneley-wave slowness and an estimated Stoneley-wave slowness wherein the estimated average Stoneley-wave slowness is computed using the effective tool modulus. A difference between the measured Stoneley-wave slowness and the estimated Stoneley-wave slowness is minimized and the horizontal shear-wave velocity value for the minimized difference is output. Transverse isotropy may be then be calculated as a function of the determined Vsh and vertical shear wave velocity, Vsv, determined from standard logging techniques.

Abstract: A method for seismic surveying is disclosed which includes towing a first seismic energy source and at least one seismic sensor system. A second seismic energy source is towed at a selected distance from the first source. The first seismic energy source and the second seismic energy source are actuated in a plurality of firing sequences. Each of the firing sequences includes firing of the first source, waiting a selected time firing the second source and recording signals generated by the seismic sensor system. The selected time between firing the first source and the second source is varied between successive ones of the firing sequences. The firing times of the first and second source are indexed so as to enable separate identification of seismic events originating from the first source and seismic events originating from the second source in detected seismic signals.

Abstract: The invention relates to a semiconductor optical amplifier including a buried guide active structure (12), characterized in that the guide active structure (12) is subjected to an external stress to render the gain of said amplifier insensitive to the polarization of the light to be amplified, said external stress coming from a force induced by a deposit of a material (50) against a ridge (15) surrounding said guide active structure (12).

Abstract: Disclosed is a bi-directional optical-amplifier module including first through fourth optical amplifiers, a mid-stage device for performing a desired signal processing for an upward or downward optical signal passing therethrough, a first optical-signal-path-setting device for supplying an optical signal inputted to a first input/output terminal of the bi-directional optical-amplifier module while outputting an optical signal outputted from the fourth optical amplifier to the first input/output terminal, a second optical-signal-path-setting device for supplying an optical signal inputted to a second input/output terminal of the bi-directional optical-amplifier module while outputting an optical signal outputted from the third optical amplifier to the second input/output terminal, a third optical-signal-path-setting device for outputting an optical signal outputted from the first optical amplifier to a first input/output terminal of the mid-stage device while supplying an optical signal outputted from the firs

Abstract: This invention relates to improved methods to generate shaped sweeps, and for the acquisition of vibroseis data with a shaped pilot sweep.

Abstract: A rare earth element doped fiber forming an optical amplifier is pumped with a plurality of pumping lights to prevent drop of the inversion population ratio in the length direction of the rare earth element doped fiber.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: A single-ended laser device for locating reflective targets within a given surveillance volume, said apparatus comprising: a body of material excitable to emit electromagnetic radiation at frequencies within a characteristic fluorescence peak, said body having an effective exit aperture; a single retro-reflective member having an optic center and positioned to receive radiation from said body and to redirect said radiation into said surveillance volume through said effective exit aperture of said body, said effective aperture being oppositely disposed on said body from said single member, said single member cooperating with said body to form a field of view within said surveillance volume substantially equal to the solid angle defined by the square of the length of a line joining said optic center of said single member with the center of said effective exit aperture divided into the area of said exit aperture transverse to said line; means for exciting said body to an energy level substantially equal to th

Abstract: There are provided a plurality of optical adjusting sections, a wavelength-multiplexing section, and a control section. The plurality of optical adjusting sections, which are provided for respective wavelength bands, amplifies light beams in the respective wavelength bands. The wavelength-multiplexing section wavelength-multiplexes amplified light beams in the respective wavelength bands. The control section controls the outputs of the respective optical amplifying sections so that optical powers of the respective wavelength bands will become approximately identical at a predetermined point when wavelength-multiplexed light of the light beams in the respective wavelength bands travels to the predetermined point. This configuration makes it possible to eliminate optical power deviations between wavelength bands that would otherwise occur when an optical signal of a plurality of wavelength bands is transmitted, and to thereby make optical SNRs uniform.

Abstract: The present invention provides a method of performing the time picking step in a VSP (vertical seismic profile) survey. In a preferred embodiment of the invention the time picking step is carried out on a combined three-component amplitude of the received seismic energy, which contains the amplitude of all the seismic energy received at the receiver. The amplitude of the direct pulse in the combined trace will not decrease to zero as the offset of the source is changed, as can be the case for the single-component amplitude of the direct pulse. In a particularly preferred embodiment of the invention, the combined three-component amplitude is calculated by summing the Hilbert instantaneous amplitudes of the x-, y- and components of the seismic data using the equation (I). The present invention also provides two new time picks. One time pick involves finding the maximum positive gradient of A(t).

Abstract: An optical amplifying apparatus which includes an optical amplifier, an optical attenuator and a controller. The optical amplifier amplifies a light signal having a variable number of channels. The optical attenuator passes the amplified light signal and has a variable light transmissivity. Prior to varying the number of channels in the light signal, the controller varies the light transmissivity of the optical attenuator so that a power level of the amplified light signal is maintained at an approximately constant level that depends on the number of channels in the light signal prior to the varying the number of channels. While the number of channels in the light signal is being varied, the controller maintains the light transmissivity of the optical attenuator to be constant.

Abstract: An optical resonator receives a light beam having a first state of polarization. The resonator comprises a polarization modifying device (40) and a polarization dependent coupling device (30) for coupling light having the first state of polarization into a first path and for coupling light having a state of polarization perpendicular to the first state of polarization into a second path. The polarization dependent coupling device (30) is arranged to receive from a first propagation direction the light beam having the first state of polarization and to couple the light beam from the first propagation direction in the first path to the polarization modifying device (40). The polarization modifying device (40) is arranged for modifying the state of polarization of the light beam before reentering the first path of the polarization dependent coupling device (30) from a second propagation direction in order to couple into the second path a portion of the light beam traveling into the second propagation direction.

Abstract: A support structure for piezoelectric elements in a marine seismic cable is provided. The support structure comprises upper and lower cylindrical halves, each with channels formed therein. Two axial channels are adapted to retain three piezoelectric elements each. A third axial channel, positioned between the sensor element channels, is adapted to retain a flexible circuit. Transverse channels between the sensor element channels and the circuit channels accommodate extension from the flexible circuit. The piezoelectric elements are mounted within their respective channels with a resilient pad with adhesive on both sides. The piezoelectric elements are graded so that any group of three piezoelectric elements exhibits approximately the same sensitivity as any of the other three groups of piezoelectric elements on the support structure.

Abstract: The present invention is a method of transmitting one or more acoustic signals in a drill string using PSK, ASK, FSK or MSFK. The method includes determining one or more stopbands and one or more passbands by testing or modeling the drill string. Two modulating frequencies are selected that are equidistant about a carrier frequency, and which are located within at least one passband. Data representative of downhole measurements or calculations are converted to signals to be transmitted at the modulating frequencies.

Abstract: This invention describes new developments in Sagnac Raman amplifiers and cascade lasers to improve their performance. The Raman amplifier bandwidth is broadened by using a broadband pump or by combining a cladding-pumped fiber laser with the Sagnac Raman cavity. The broader bandwidth is also obtained by eliminating the need for polarization controllers in the Sagnac cavity by using an all polarization maintaining configuration, or at least using loop mirrors that maintain polarization. The polarization maintaining cavities have the added benefit of being environmentally stable and appropriate for turn-key operation. The noise arising from sources such as double Rayleigh scattering is reduced by using the Sagnac cavity in combination with a polarization diversity pumping scheme, where the pump is split along two axes of the fiber. This also leads to gain for the signal that is independent of the signal polarization.

Abstract: The present invention is an amplifier for amplifying an optic signal. The amplifier includes a signal source transmitting the signal, which includes a signal portion in the L-band. The signal first passes into a first signal manipulator. The first signal manipulator is one or more collimators and/or concentrators and, in some embodiments, can include dichroics or optical manipulators known to those skilled in the art. An input pump is aligned to overlap the signal with pump light. From the first signal manipulator, the signal and the pump light intersects the erbium doped crystal, wherein the pump light excites the crystal and the signal impinges the crystal, amplifying the signal.

Abstract: Optically pumped rare-earth-doped polarizing fibers exhibit significantly higher gain for one linear polarization state than for the orthogonal state. Such a fiber can be used to construct a single-polarization fiber laser, amplifier, or amplified-spontaneous-emission (ASE) source without the need for additional optical components to obtain stable, linearly polarized operation.