Abstract: This invention provides apparatus and methods for converting a lightwave of an arbitrary polarization propagating in a single mode optical fiber into a wave having a single linear polarization state. A polarization couples light of an undesired polarization out of the fiber, and a photodetector produces an error signal responsive to light coupled from the fiber. Control circuitry processes the error signal to produce control signals which are input to a polarization of light input to the polarizer to null the error signal. With the error signal maintained at a minimum value the light input to the polarizer and, hence, the light ouput therefrom is a wave having only the desired linear polarization.

Abstract: This invention relates to fiber optic frequency shifters for producing optical signals of a desired frequency range for input to a device such as an optical rotation sensing system. The rotating birefringence is created in a length of fiber optic material, which has the effect of a rotating half-wave plate upon an input optical signal. The length of fiber optic material may have a jacket of either an electrostrictive or a magnetostrictive material formed thereon such that application of an appropriate field to the jacket compresses the enclosed fiber to induce birefringence therein by means of the photoelastic effect. A half-coupler having a block of electro-optically active birefringent material adjacent the interaction region combined with an electrode configuration and circuitry for producing a rotatiing electric field in the block also produces a rotating half-wave plate frequency shifter.

Abstract: The cladding and a portion of the core of a length of optical fiber are removed to form an interaction region. A form birefringent stack is positioned on the exposed core. The refractive index of the stack for polarizations parallel to the plane of the interaction region is approximately equal to the refractive index of the fiber core so that these polarizations radiate from the fiber. The refractive index of the stack for the polarization normal to the plane fo the interaction region is approximately equal to the refractive index of the cladding so that this polarization remains guided by the fiber. A photodetector forms an error signal from the polarization radiated from the fiber, and control circuitry processes the error signal to drive a polarization controller that adjusts the polarization of light input to the polarizer to minimize the error signal.

Abstract: A device for testing containers as to leakage and defects is comprised of a container sealing portion (4), a pressure exerting portion, and a pressure gauge (8). Said pressure exerting portion is provided in the shape of a piston/cylinder system (2, 3) that is maintained in an extended position by a tensioning means, e.g. a spring (5). Said container sealing portion (4) is provided either on the piston (2) or on the cylinder (3) for sealing contact with the container opening. The chamber between the cylinder (3) and the piston (2) is in communication with the pressure gauge (8) and, via a channel (13) in the container sealing portion (4), with the interior of the container (1). The device may, furthermore, be provided with a feeler means (12-19) for testing the container as to moulding films and the like.

Abstract: Laser detection apparatus comprising a laser defining an active region and providing a double beam of coherent radiation, a sample to be tested located in a first part of the double beam of coherent radiation, a radiation detector arranged to receive radiation passing through the sample to be tested for providing an output indication of absorbance, a reference sample disposed in a second part of the double beam, apparatus for sensing absorption of the coherent radiation at the reference sample, apparatus for providing selectable heating of the active region of the laser, and apparatus for providing a control signal to the selectable heating apparatus in accordance with the sensed absorption of the coherent radiation at the reference sample.

Abstract: This invention relates to an electrically switchable fiber optic directional coupler. Two oppositely oriented blocks of an interaction material are placed adjacent the fibers in an evanescent field coupler. Application of an electromagnetic field to the interaction material increases the refractive index of one fiber and decreases the refractive index of the other. The change in refractive indices of the blocks of the interaction material increases the propagation constant of one fiber and decreases that of the other fiber. The coupling of optical signals between the fibers may be varied between zero and l00% by controlling the applied field to change the propagation constants between values that provide complete cross coupling of light from one fiber into the other and straight through propagation provides an electrically controllable switching action.

Abstract: This invention relates to fiber optic apparatus and methods for polarizing light for use in fiber optic devices, such as rotation sensors. A phase grating formed of alternating layers of dielectrics having different indices of refraction is placed adjacent a half coupler that includes a fiber having a cladding thickness which forms an interaction region. The evanescent field of light of a selected polarization interacts with the phase grating to cople out of the fiber while light of a second selected polarization remains in the fiber.

Abstract: A locking shaft extends through passages in a mounting bracket, a seat bracket and a seat cover bracket to prevent small children from raising the seat and seat cover. The locking shaft and a plunger are mounted to an end cap with the plunger being slidable within an axial passage in a rod upon which the brackets are mounted. A spring connected to the plunger inside the axial passage biases the locking shaft toward a locked position. In order to unlock the seat and seat cover, a person must pull the locking shaft out of the passages in the seat bracket and the seat cover bracket and raise the eat and seat cover, or just the seat cover if so desired, after placing the locking shaft in the unlocked position.

Abstract: A machine for slicing matting of brittle fiber material comprising an elastomeric coated anvil roller and a slicer roller having a plurality of cutting discs mounted on an axis parallel to the longitudinal axis of the anvil roller, which depress the matting into the elastomeric material of the anvil roller sufficiently to break the brittle fibers. The sliced matting can then be conveniently cut transversely on the same machine, if desired, to form diced brittle fiber matting. The diced matting, e.g., of fiberglass is a way of facilitating the separation of short fibers from fiberglass matting to produce raw material for forming new matting, or the diced brittle fiber matting, e.g., fiberglass or carbon fiber matting may be used as such.

Abstract: This invention provides a sensor array using a plurality of fiber optic sensors connected between transmit fibers and receive fibers. The laser transmitter supplies pulses to the transmit fiber and fiber optic couplers couple the pulses from the transmit fiber into the fiber optic sensors. The pulses from the laser transmitter may be frequency chirped or frequency stepped to provide passive sampling of interferometric sensors in addition to intensity sensors, or otherwise frequency modulated. Each sensor is configured to respond to changes in a predetermined physical parameter by altering the shape of the pulse input thereto. Fiber optic couplers couple the sensor output signals into the receive fiber for input to a receiver, which converts the optical signals into electrical signals for input to a processer. A timing reference correlates the sensor output pulses with the sensors.

Abstract: A shield tunnel boring machine having at its boring head a pressure-resisting mud kneading chamber defined by a bulkhead, wherein the bulkhead is divided into outer peripheral and central bulkhead parts. The outer peripheral bulkhead part is fixed to the inner periphery of a cylindrical shield. The central bulkhead part is made rotatable in association with a head-positioned rotary cutter as driven by a main motor. The sealing means required for the bulkhead is limited to seal one for a gap between the fixed outer peripheral bulkhead part and the rotatable central bulkhead part and the number of necessary related parts can be remarkably reduced.

Abstract: A chlorination system for distributing chlorine in a hot tub or spa. The system regulates the flow of water through a mixing chamber with a valve or stopcock to control the rate of chlorine distribution. An assembly of venturis and baffles also regulates the flow of water through the mixing chamber and controls the size of particles of chlorination tablets that will flow out of the chlorination system.

Abstract: A wheel protector is formed as a tray to fit inside a dish-type truck wheel to collect lubricants and other material as an axle is removed from the truck without demounting the wheel from the truck.

Abstract: This invention controls the air pressure in an aircraft cabin in response to a selected landing field altitude and to a selected maximum permissible cabin pressure rate.

Abstract: A post support and protector includes a pair of members having first portions for attachment to a post and second portion for anchoring within the earth.

Abstract: A variable-speed, leading power factor AC machine which may be supplied through a line-commutated inverter.

Abstract: A low voltage, high frequency actuator for correcting distortions in laser optics systems.

Abstract: An interpole for a direct current dynamoelectric machine is provided at the tip thereof with a flux shift winding, or windings, to effect a shifted magnetic flux strength to counteract induced voltages of the commutated armature coils moving through the commutating zone.

Abstract: The discharge of a capacitor energizes a relay to actuate the dump valve of a braking system to interrupt braking action upon the occurrence of wheel slide.

Abstract: A pulse width modulated three-phase inverter has notches in the output waveforms to control the harmonic content thereof.