摘要:
An apparatus for enabling acousto-optic communication comprising an in-water platform comprising means for emitting an acoustic signal to an acousto-optic interaction zone, an in-air platform comprising the ability for transmitting a first optical interrogation beam, the ability for receiving a portion of the first interrogation beam and a second laser beam formed from the reflection of the first interrogation beam off of the acousto-optic interaction zone, the ability for measuring and outputting a plurality of optical interferences between the portion of the first interrogation beam and the second reflected beam, and a signal converter receiving as input the plurality of optical interferences and outputting an electrical signal representing the received acoustic telemetry signal at the interrogation point at the air-water interface.
摘要:
The present invention includes a system and method of use for communications from an in-air platform to a submerged platform. The system includes a laser positionable on the in-air platform above a water medium that sends a pulsed information-bearing laser beam containing a modulated communications signal to create and react in a non-linear regime manner with the water medium at an air/water interface. The beam vaporizes and optically breaks down a portion of the water medium, creates a shock wave and generates bubble oscillations at the vaporized portion. An acoustic sensor on the submerged platform detects these shock wave oscillations within the water medium and a demodulator-decoder that identifies these broadband acoustic transients that contain deterministically placed energy and demodulates-decodes the acoustic transients into the transmitted communications signals from the in-air platform.
摘要:
The present application provides a linear mechanism for optical-to-acoustic energy conversion for optoacoustic communication from an in-air platform to an undersea vehicle. Signals used in underwater acoustic telemetry applications are capable of being generated through the linear optoacoustic regime conversion process. A number of issues concerning linear optoacoustic communication is addressed that lead to a formulation of a linear regime optoacoustic communication scheme. The use of oblique laser bean incidence at an air-water interface to obtain considerable in-air range from the laser source to the vehicle is also addressed. The effect of oblique incidence on in-water range is addressed as well. Optimum and sub-optimum linear optoacoustic sound-generation techniques for selecting the optical wavelength and signal frequency for optimizing in-water range are identified. Optoacoustic techniques employing M-ary frequency shift keying and multifrequency shift keying are compared with communication parameters such as bandwidth, data rate, range coverage and number of lasers employed.
摘要:
A device (gage, data station, and software) and method to measure mean radius and deviations from mean radius of nominally cylindrical or conical shapes in a plane perpendicular to the nominal axis of revolution using curvature measurements at uniformly spaced intervals about the circumference is described. The system divides the contour of interest into equal segments and measures the local curvature at each point. The group of measurements combines with a closure constraint to produce a condition of mathematical overcompleteness. This is used to minimize the accumulation of measurement error.
摘要:
An acoustic sensing device includes a housing having an internal cavity filled with a vibration decoupling medium. An acoustic window formed of an acoustically transparent material is mounted in the housing. This mounting can be by antivibration mounts to prevent housing noise from affecting the acoustic window. A scanning laser vibrometer is positioned within the housing and directed to detect vibrations of the acoustic window. Antivibration mounts are joined between said scanning laser vibrometer and said housing. In further embodiments, the scanning laser vibrometer detects vibrations at a plurality of locations on the acoustic window forming a virtual array.
摘要:
A method is provided for remotely measuring index of refraction fluctuations. From a first location, an optical beam is focused at a focal plane located at a second location in a medium of interest. As a result, a beam of energy is backscattered towards the first location. At the first location, a size of the backscattered beam is determined where the size is indicative of strength of fluctuations in the medium's index of refraction.
摘要:
An acoustic sensing device includes a housing having an internal cavity filled with a vibration decoupling medium. An acoustic window formed of an acoustically transparent material is mounted in the housing. This mounting can be by antivibration mounts to prevent housing noise from affecting the acoustic window. A scanning laser vibrometer is positioned within the housing and directed to detect vibrations of the acoustic window. Antivibration mounts are joined between said scanning laser vibrometer and said housing. In further embodiments, the scanning laser vibrometer detects vibrations at a plurality of locations on the acoustic window forming a virtual array.
摘要:
A system for determining spatial coherence, temporal coherence or both of an optical signal includes a fiber bundle containing optical fibers. Optical fiber inputs are arranged in proximate groups having the same number of fibers. The groups can each receive a portion of the optical signal. Each fiber in the group has a gross length that differs from the other fibers, but each group has the same set of different gross lengths. The fibers are joined to a lens which spreads the optical signal and causes interference between portions of the signal. This interference is detected at a detector. A computer joined to the detector can measure spatial and temporal coherence from the interference. Other embodiments feature multiple detectors and reflection along the bundle.
摘要:
A system is provided to generate coherent single-frequency and single transverse mode light pulses. A laser produces a linearly-polarized continuous wave beam defined by a single longitudinal and transverse mode. A first rotator processes the beam such that optical polarization is rotated during a first time period and not rotated during a second and third time period. A second rotator is operated during the first period to rotate optical polarization of the beam, during the second period to not rotate the beam, and during the third period to rotate the beam. An optical loop amplifies the beam during the first and second periods. An amplifier device can be added to the loop for amplification. A first beam splitter allows the beam to enter the loop and a second splitter directs the beam along the loop during the first and second periods and out of the loop during the third period.