Abstract: Shock resistant microchannel plate assemblies incorporating stacked or cascaded microchannel plates, and to methods of their use are disclosed. High-output amplification tubes of the photomultiplier type, or of the image intensifier type, having a plurality of sequentially arranged, or cascaded, electron multiplier microchannel plates are also disclosed. More particularly the present invention relates to a high output photomultiplier tube or image tube having cascaded microchannel plates radially constrained by an annular insulating ring. In another aspect of the present invention image intensifier tubes or photomultiplier tubes may include a tapered ceramic high voltage stand-off. Moreover, a method of making such tubes is also disclosed.

Abstract: A flip-up helmet mount for a night vision goggle includes a plurality of nested relatively movable brackets, the first of which is secured to a user's helmet. A second bracket pivots relative to the first to provide flip-up motion for the night vision goggle, and a third of the nested brackets is pivotal on the second bracket to provide a tilt angle adjustment for the night vision viewer. In order to both save battery power, and to prevent the user from inadvertently revealing his position by forgetting to turn off the night vision viewer before flipping it up, the support structure includes a magnetic flux source cooperable with a magnetically-responsive switch of the night vision viewer to maintain the viewer turned on only when the viewer is in its use position.

Abstract: Fluid cleaning apparatus for precision parts, comprising in combination, a chamber, having a fluid inlet and a fluid outlet, for holding parts to be cleaned and a fluid tight recirculating flow system including the chamber. The fluid tight system directs supercritical carbon dioxide fluid flow across the parts being cleaned. A fluid recirculating cylinder has a first fluid port and a second fluid port connected in the flow system. A fluid piston is in the cylinder between said ports. A pneumatic cylinder has a further piston between a first pneumatic port and a second pneumatic port. A driving member is connected between the pistons for reciprocal movement caused by air from a source alternately introduced to the pneumatic ports to cause the fluid piston to pump fluid through the chamber and back to the recirculating cylinder. A shuttle valve is connected between the air source and the pneumatic ports.

Abstract: A method and apparatus are provided for addressing the effect of centripetal acceleration upon estimates of cross-track velocity, for determination of east gyro bias error, generated with a taxiing aircraft. After initial estimates of crab angle, ratio of crab angle to centripetal acceleration and lever arm are provided, velocity, heading angle and heading angle rate are observed as the aircraft taxis. An estimated value of centripetal acceleration is taken as the product of heading angle rate and heading velocity. Cross-track velocity is computed from cross-heading velocity and this is integrated to generate cross-track position. A Kalman filter generates various gains, including one associated with the ratio of crab angle to centripetal acceleration, for error allocation.

Abstract: A combination tuner and harmonic suppressor apparatus is provided for a klystron having a gap defined across a resonant cavity. The apparatus comprises a back cavity coupled to the resonant cavity by a coupling iris. Harmonic resonances within the resonant cavity are conducted to the back cavity through the coupling iris. An absorber disposed within the back cavity absorbs and attenuates the energy of the harmonic resonances. The coupling iris can be capacitively tuned to optimally conduct the harmonic frequencies into the back cavity. The apparatus further comprises an open-ended diaphragm providing a wall of the resonant cavity, disposed between the back cavity and the resonant cavity. A bellows provides a barrier between a vacuum environment within the klystron and a non-vacuum environment external to the klystron, and enables a broad range of movement of the diaphragm.

Abstract: An accelerometer is fabricated by forming a proofmass and at least one associated hinge in a silicon substrate by ion implantation and the formation of an oxide support layer below the proofmass, subsequently integrally bonding two complementary proofmass and substrate structures together, and then removing the oxide support layer to leave the proofmass supported by the hinge within the body of silicon material. The proofmass may be electrically connected to a lead extending through an etched recess in one of the substrates; and the proofmass may be electrically isolated or separated from the substrates by an oxide layer and by a change in conductivity type of the semiconductor material where the hinge is structurally mounted to the substrates.

Abstract: A plurality of air-backed elongate mandrels are arranged in an planar array such that their longitudinal axes are parallel. A length of a first optical fiber is wound around portions of each mandrel in a first group of the mandrels for exposure to the parameter. The first optical fiber is arranged such that exposing it to the parameter to be sensed causes the length of the first optical fiber to increase and decrease in direct proportion as the parameter increases and decreases. A length of the second optical fiber is wound around a second group of the mandrels for exposure to the parameter. The second optical fiber preferably is arranged such that exposing it to the parameter to be sensed causes the length of the second optical fiber to increase and decrease in inverse proportion as the parameter increases and decreases.

Abstract: An output system for a multioscillator includes a mixture of optical and electronic subsystems for separating and deriving the a.c. and d.c. HET signals of the right and left circularly polarized modes. An output prism includes a plurality of optical coatings for introducing predetermined phase shifts between the s and p components of light derived from the beams that counterpropagate within the cavity. A pair of polarizers receive the output beams from the prism. Predetermined orientations of the polarizers provide differential intensities for the HET outputs of right and left circularly polarized light, thereby enabling photodetectors to generate electrical signals representative of the a.c. and d.c. HET outputs of left or right circularly polarized light. An output circuit includes high and low-pass filters for separating the a.c. and d.c. HET signals for each polarization.

Abstract: A method for bonding thermally-mismatched elements of a traveling wave tube employs a metallic plate of undulating character. The plate is located at the region of the interface between tube elements formed of materials of materially-differing thermal character such as the ceramic termination piece and an adjacent sever pole piece of copper. Through either a brazing or a sintering process, pluralities of bonds are formed at points of tangency between the plate and the two elements of differing thermal expansion coefficients. As a result, a good heat flow path, accompanied by a more stable r.f. interface, is formed between the materials that is not subject to fracture as are prior art diffusion bonds.

Abstract: A digital force balanced instrument such as an accelerometer that incorporates a directly digital electrostatic forcer with servo loop plates charged by a digital feedback loop is disclosed. The accelerometer has a proofmass electrode suspended in a cantilever configuration between electrodes on either side thereof, which proofmass is displaced upon acceleration. Each side electrode includes a plurality of electrostatic plates sized in binarily weighted multiples of area. An induced signal in the proofmass electrode is quantized via A/D converter in the feedback loop, which activates the appropriate number of plates to force the proofmass to an initial position.

Abstract: An optical sensor that is particularly useful for measuring ground borne vibrations employs a planar optical waveguide structure to form a sensor for detecting ground born velocities and accelerations. An optical interferometer is used to detect phase shifts in optical signals guided by the waveguide caused by external vibrations. A pair of phase modulator electrodes is placed adjacent one of the legs of the interferometer and a coil of wire is connected between the pair of electrodes. A sensing element that produces a voltage in response to vibrations is connected across the electrodes. The voltage produced by the sensing element is applied to the pair of electrodes to cause phase modulation of optical signals guided by the leg of the interferometer adjacent the electrodes. The optical signals output from the interferometer are then processed to determine the velocity and acceleration associated with the vibration.

Abstract: A day/night sight includes a visible-light first optical path and an invisible-light second optical path which are everywhere optically coaxial. The invisible-light second optical path leads to a detector or to an image intensifier tube for providing either an electrical signal or a visible image, respectively, in response to the invisible-light image. A third optical path for the visible image from the image intensifier tube is also everywhere optically coaxial with the first and second optical paths. A visible image produced from the electrical signal is introduced into the first optical path to thereafter be coaxial therewith. Consequently, a uniquely compact arrangement of the elements for the day/night sight is achieved.

Abstract: A apparatus for tuning a resonant cavity of a magnetron is provided which prevents undesired frequency fluctuation during thermal cycling or vibration. The magnetron has an axially disposed resonant cavity comprising a plurality of radially disposed anode vanes. Alternating ones of the vanes are electrically connected together by a first and a second strap, respectively. The tuning apparatus comprises a tuner shaft having a threaded outside diameter, a vertical gear having a threaded inside diameter engaging the threaded outside diameter of the tuner shaft, and a worm gear engaging the vertical gear. Rotation of the worm gear translates to axial movement of the tuner shaft. A ceramic cylinder is coupled to the tuner shaft at an end adjacent to the resonant cavity, and extends into a space defined between the first and second straps by the axial movement of the tuner shaft. Disposition of the ceramic cylinder within the space alters capacitance measurable between the straps.

Abstract: Disclosed herein is an apertureless ring laser gyroscope which achieves higher order transverse mode suppression without the use or need for a restrictive aperture that can be a source of unwanted scatter. Such mode suppression is achieved by operating the ring laser gyroscope in a higher pressure range (from 12 to 18 torr) than the range normally considered for ring laser gyroscope operation. Through the mechanism of pressure broadening and mode competition, the lower order TEM.sub.00 mode remains the only transverse mode present in the optical cavity of the ring laser gyroscope.

Abstract: A photomultiplier includes a cascade of microchannel plates which are physically and electrically connected to provide an electron multiplication through the microchannel cascade. One of the microchannel plates is a high-output microchannel plate providing a high level of electron multiplication. This high output microchannel plate is thermally conducted to ambient by a heat transfer path including outwardly disposed microchannel plates in the cascade. A unitary ceramic housing defines a vacuum envelope for the photomultiplier.

Abstract: Microchannel plates for use in image intensifiers and night vision devices having both improved gain and signal-to-noise ratio are provided. The microchannel plates provide an initial electron impact area having a surface electron-emissivity coefficient greater than one (1) that is not occluded by low electron-emissivity conductive coatings. In one embodiment angulated deposition of a coating material is used to provide a high electron-emissivity initial electron-impact area while in another embodiment nonmetallic electrodes provide increased amplification of a signal electron. Besides improving gain and sensitivity, the microchannel plates of the present invention provide a higher signal-to-noise ratio, better resolution, high open area ratios and are significantly more cost effective to produce.

Abstract: At least one coil (32) is located on an exterior side face (30) of a frame (12) of a ring laser gyroscope (10) such that a significant component of the magnetic field generated by the coil is colinear with the plasma discharge of the gyroscope, and by which dispersion equalization of the gyroscope can be effected. The coil may be supported by a magnetically permeable annular bobbin (40), which is set about a mirror (26) on side face (30) and which may be partly set within grooves in the side face, to reduce the current necessary to effect dispersion equalization and to provide shielding of the mirror from the effects of tangential and transverse fields, and to increase the shielding effects for the mirror, both from Faraday rotator magnets (16) and from external magnetic fields. For those mirrors where no coils are present, the annular bobbins are used solely for their shielding properties.

Abstract: The ends of a pair of polarization-maintaining optical fibers that each have an elliptical stress member in the cladding to produce stress induced birefringence are placed end-to-end with a predetermined gap between the ends of the fibers. The ends of the fibers are examined with an optical imaging apparatus whose focus is adjusted to locate an alignment band in each fiber. The position of one of the polarization-maintaining optical fibers is then adjusted until the two alignment bands are in longitudinal alignment. The fiber ends are pre annealed and then fused together by application of energy from an electric arc.

Abstract: A light transparent window is fabricated to absorb a band of radio frequency (RF) energy with minimal RF transmission and reflection. The window is formed from a series of parallel electrically conductive sheets separated by absorbing cavities. The conductive sheets are formed by depositing a layer of doped semiconductor material onto a thin layer of sapphire. The absorbing cavities are formed by an air-filled space between the conductive sheets. Radio frequency reflection can be further attenuated by an antireflection coating, which is preferably realized by a non-conducting sapphire sheet separated from the series of conductive sheets by an air-filled space. Depending on the number of cavities, reflection and transmission attenuation of over 25 dB can be obtained for radio frequency energy in the 2 to 18 GHz band.

Abstract: A wide band radio frequency measurement probe assembly is described for use in connection with circuits constructed of microstrip circuitry. The probe includes a resistive voltage divider connected to a microstrip transmission line enclosed in a hand held housing. Ground points for engagement with ground contacts on the probe are provided on the circuit board substrate and are plated through to a ground plane on the other side of the substrate.