Abstract: A simultaneous data communication and fiber perturbation detection system includes a narrow band optical data signal from a source 10 which is polarized by a polarizer 14 along a slow polarization axis of a polarization preserving birefringent optical fiber 28, and a broadband probe optical signal from a source 20 which is polarized along a fast polarization axis of the fiber 28. A perturbation 32 in the fiber 28 causes a portion of the probe signal to be coupled onto the orthogonal slow polarization. At the receiving end of the fiber 28, a beamsplitter 34 splits the signal along a path 36 which extracts the data signal to be received by a data receiver 44, and a path 38 which extracts the probe signal and employs an adjustable interferometer 58 to determine the location along the fiber 28 where the perturbation 32 exists. The central wavelengths .lambda.1,.lambda.2 of the data and probe optical signals may be the same or different.

Abstract: A broadband laser which can be electronically tuned to a narrow line by insertion of a frequency selective element in the laser cavity.

Abstract: A FOG system with a high polarization extinction ratio includes an integrated optic circuit (IOC) having a waveguide array fabricated by a proton exchange (PE) process, the IOC being operatively connected for providing single mode, single polarization filtering of incident light guided from the FOG light source to the sensing loop and of the interference signal guided from the sensing loop to the detector.

Abstract: In a fiber optic gyroscope 10 having a pair of light waves counter-propagating in a fiber optic loop 44, a phase modulator 28 driven with a variable frequency and amplitude modulation signal on a line 32 so as to null any rotation induced optical phase shift, and using the difference between the drive frequency and the loop eigenfrequency as a measure of rotation rate, is provided with a calibration circuit which determines the actual loop eigenfrequency while in rotation. A modulation signal is applied having an amplitude that causes the closed loop output frequency to equal the loop eigenfrequency independent of rotation rate. The amplitude is fine tuned by applying a phase dither and adjusting the amplitude until effects of the dither are minimized.

Abstract: In a fiber optic rotation sensor, two phase modulators are symmetrically offset with respect to the center of an optical fiber loop and alternately excited by a waveform whose frequency alters the differential phase between counter-propagating light waves in the loop to maintain a fixed intensity signal at a detector upon loop rotation. The difference between the waveform frequencies is proportional to the speed of sensor rotation while the mean value of the waveform frequencies equals the frequency value in the absence of sensor rotation. In the alternative, a single modulator is excited by a waveform whose polarity is reversed at intervals of time.

Abstract: A low cost fiber optic gyro includes a Sagnac interferometer configured in a minimum reciprocal configuration and modified to use a 0.8 micron wavelength laser diode as the interferometer light source and 1.3 micron, single-mode fiber for the sensing coil.

Abstract: In a fiber optic rotation sensor having a pair of light waves counter-propagating in an optical waveguide loop, a phase modulator is driven by a modulating signal at the loop eigenfrequency. Upon exiting the loop the waves are combined into a light intensity signal which is sensed, the sensed signal including a component in quadrature with a desired rotation rate component, the magnitude of the quadrature component being proportional to any deviations in the frequency of the modulating signal from the loop eigenfrequency. The phase modulator is servo-controlled so as to drive the quadrature component to zero, thereby compensating for any deviations in the modulator frequency from the loop eigenfrequency.

Abstract: Orientation and/or position of a first body, such as the inboard end 42 of a helicopter blade 21, with respect to a second body, such as a rotor hub arm 36, is sensed by determining the position of the images 93, 95-97, of light from sources 80, 81 passed through slits 89, 90 on detector arrays 91, 92. Signal processing means (FIG. 5, FIG. 11) provide signals indicative of such image positions, which can be used to determine, from simple trigonometry, the orientation and/or position of the first body.

Abstract: An integrated optical pressure transducer having a diaphragm fabricated from a low-loss glass is positioned at the location where pressure changes are to be measured. An optical waveguide loop formed on one surface of the diaphragm acts as a ring cavity in which the difference between the resonating frequencies varies with pressure but not with temperature. Light energy is coupled into the waveguide loop from an optical source through a tangentially located input waveguide. An output waveguide, also tangentially located, couples light energy from the waveguide loop to a broadband detector so that the changes in frequency spectrum of the resonating frequencies within the waveguide loop can be monitored.

Abstract: A display device employs an electric discharge passing through a mixture of gases to form an excimer that fluoresces in the blue/green region of the optical spectrum.

Abstract: A device for detecting displacements of a fluid jet is disclosed. The device is particularly suitable for use as part of a fluidic angular rate sensor. The device comprises a wire resistor suspended between a pair of metal posts, a means for producing a magnetic field at the location of the resistor, an alternating current (AC) source electrically connected across the resistor for heating the resistor and for interacting with the magnetic field to cause the resistor to oscillate, and readout electronics for sensing changes in wire resistance which are a function of wire temperature variations associated with fluid jet displacements. The use of a single oscillatory wire resistor eliminates the need for the difficult to achieve and costly wire matching procedures of conventional two wire fluid jet displacement detectors.

Abstract: A fluidic angular rate sensor employs an ionized stream of gas 104, the deflection of which is detected by an amplifier 130 connected to a pair of collection electrodes 122 and 124, motive power for the gas stream 104 being provided by momentum transfer from ions in a corona discharge.

Abstract: Disclosed are very fine wires, of the order of 3-6.times.10.sup.-6 m diameter, having cross sections which are uniform within .+-.3%. A common drawn tungsten wire is electrolytically etched to a fine diameter, of the order of 2-4.times.10.sup.-6 m. The variations in cross sectional area along the etched wire are eliminated by selectively vapor depositing tungsten on the surface while using resistance heating. The very fine uniform wires enhance the performance of devices such as fluidic angular rate motion sensors.

Abstract: An axial magnetic field applied to the laser gain medium of a laser gyro provides, through the Zeeman Effect, a pair of gain versus frequency profiles relating to respective counter-rotating waves (clockwise and counterclockwise) with their frequencies of maximum gain displaced from one another by an amount which is proportional to the applied magnetic field, and which is substantially equal to the frequency difference caused by an applied directional bias, such that the separation between the frequency of each wave and the frequency of maximum gain of the related gain profile is the same for both waves. This causes the counter-rotating waves to operate on points of equal phase (or index of refraction) on the corresponding dispersion characteristic curve associated with the related gain versus frequency profile.

Abstract: Disclosed is a technique for producing vapors of metals in containment vessels that experience the melting temperature but not the boiling temperature of the metal being vaporized. The metal is maintained in molten pools by the containment vessel. Pumping means such as wicks transfer the metal from the pools to a higher temperature region internal of the containment vessel where the liquid metal is boiled into a vapor. The generation of laser radiation from an excited metal vapor produced in this manner is also disclosed.

Abstract: A low cost fiber optic gyro includes a Sagnac interferometer configured in a minimum reciprocal configuration and modified to use a 0.8 micron wavelength laser diode as the interferometer light source and 1.3 micron, single-mode fiber for the sensing coil.