Abstract: Disclosed herein is a ring laser gyroscope having a non-reciprocal polarization rotation device such as a Faraday rotator configured to provide, through use of a Faraday magnet, a relatively uniform magnetic field across the profile of the Faraday rotator. By providing a uniform magnetic field across the diameter of the Faraday rotator, the magnetic lensing effects are reduced and the thermal sensitivity of the gyroscope's bias is substantially reduced.

Abstract: Monocrystalline lanthanum orthogallate compositions grown along a predetermined crystallographic direction in the form of a single crystal of a size greater than 1 cm in diameter/width and at least 10 cm in length are described. Such compositions include mixed crystal monocrystalline lanthanum orthogallates wherein a portion of the lanthanum is replaced with a rare earth element of smaller ionic radius than lanthanum and/or a portion of the gallium is replaced with Al, Sc or In. The foregoing monocrystalline compositions are particularly suited as superconductor substrates.

Abstract: A method for producing a narrow band anti-reflective film on a substrate, and the film produced by that method.Uses the concept of considering a multifilm dielectric to be an equivalent two-film dielectric, then removing a predetermined thickness of the outer, lower dielectric, film to cause the complete multifilm to become anti-reflective.When limited numbers of film materials are available, uses an EIL or effective index layer concept to obtain a predetermined index of refraction which improves the tolerance of the reflection of an anti-reflective film to film thickness errors.

Abstract: An apparatus and method for controlling the length of a multioscillator cavity. A photodiode mixes a pair of beams rotating in the same direction, one of said beams being substantially left circularly polarized, and the other beam being substantially right circularly polarized. A local oscillator causes the mixed beams to be modulated. An amplitude demodulator demodulates the modulated beams. An error detecting device responds to the amplitude demodulators, and an active integrator integrates the detected error. A piezotransducer responds to the output of the integrator for controlling the length of the multioscillator cavity.

Abstract: Disclosed herein is a method and apparatus for achieving scatter symmetrization in a multi-mode non-planar ring laser gyro. The retro scatter effect which results in scatter coupling in each of the left and right circular polarized sets of beams is equalized, so that the scatter coupling may be common-mode rejected during the analysis phase of the ring laser gyro operation. This equalization is achieved by unique orientation of the mirrors and the non-reciprocal polarization rotator. The non-reciprocal rotator which may be a Faraday rotator, is rotated in such a manner that its angle of rotation relative to an angle fixed at the plane of incidence of one of the mirrors of the leg is proportional to the positioning of the rotator along the axis between the mirrors of this leg. In this manner equal scatter coupling will occur in the left and right circularly polarized light and this scatter coupling may be common-mode rejected for purposes of deriving accurate rotational information.

Abstract: A thin film superconducting device is described in which the substrate is a single or mixed single crystal of lanthanum orthogallate grown from a pure melt of lanthanum, gallium and additive oxides. A portion of the gallium single crystal can be replaced by Sc, Al or In and/or a portion of the lanthanum can be replaced by a rare earth element of smaller ionic radius than lanthanum to allow for manipulation of the lattice constant.

Abstract: Disclosed herein in a side mounted aperture and a Faraday rotator assembly useful in conjunction with an out-of-plane multi-oscillator ring laser gyroscope. The aperture and Faraday rotator assemblies contain components which are optically contacted to one another as well as the ring laser gyroscope frame. The assemblies disclosed herein provide a simplified construction designed to fixture the Faraday rotator element in order to minimize handling and facilitate alignment to the ring laser gyroscope cavity, free from contamination and in proper alignment for optimum use of the Faraday rotator component and aperture needed for proper operation of an out-of-plane multi-oscillator ring laser gyroscope.

Abstract: An active polarization control system, which provided two dimensional optical waveguide birefringence modulation, provides polarization control in systems such as fiber optic rotation sensors and coherent fiber optic communications systems without the necessity of using costly polarization preserving fiber. In a rotation sensor, the signal output from the sensing loop is used to form feedback signals for correcting polarization state errors. The feedback signals are used to provide the corrective voltage applied to two banks of orthogonally modulated birefringence transducers situated inside the rotation sensing loop. In a coherent fiber optic communications system orthogonal modulation of two banks of birefringence transducers situated in either the communications or local oscillator signal arms at the receiver provides the required feedback signals for polarization control.

Abstract: A wavefront correction system is provided which uses an achromatic null lens to correct various aberrations introduced in a spherical wavefront when the wavefront is reflected off a non-spherical surface, particularly a parabola. Chromatic aberration, including spherochromatism, is corrected over a relatively wide bandwidth. When used in conjunction with an interferometer and a variable wavelength source, the wavefront correction system provides adequate means for determining relative position errors of the segments of a segmented mirror. The derivative of the phase error is obtained with wavelength by measuring interference for different wavelengths of light. This allows position errors of greater than one half wavelength to be accurately measured.

Abstract: The invention is a hinge assembly made of two parts, specifically for an accelerometer. The first part is adapted to be attached, either directly or through a bracket, to an inertial acceleration sensor. The second part is adapted to be rigidly attached to an apparatus whose acceleration is to be measured. The two parts are connected by a flexible hinge.The invention resides in the placement of the hinge and in the attaching means for the second part of the hinge frame as well as in the method for fabricating the novel attaching means.The hinge is not attached to the center of the opposing edges of the first and second parts of the hinge frame. It is attached to one end of those opposing sides at a first region of the second part of the hinge frame. The hinge line is generally parallel to those opposing sides.The second part of the hinge frame is clamped only in a second region away from the hinge.

Abstract: A coupling guard insures that a plurality of plugs are coupled to plural receptacles in a desired sequence. An array of cam rings which rotate in unison with the rotation of mating plugs are designed to be locked against rotation unless the rings are rotated in the desired sequence. In one embodiment, cover plates coupled to the cam rings cover the entrance to the adjacent receptacles and are removed from the entrance of the receptacles by rotation of the cam rings.

Abstract: Doped lanthanum orthogallate laser materials produced in the form of large perovskite-type doped single crystals are disclosed. Doped single crystals of lanthanum orthogallate are grown from a pure melt of lanthanum oxide, gallium oxide and dopant oxide while controlling the major crystallographic direction of solidification. Dopants are selected from the rare earth series elements, first transition series elements and actinide series elements.

Abstract: A method and apparatus are disclosed for closed-loop phase modulation to measure rate and control phase modulator gain errors in an electrical signal representing the phase difference between first and second light signals from light waves counterpropagating in an interferometric rotation sensor including a closed light path with a phase modulator in the path. The disclosed method and apparatus correct phase modulator gain in a way that is independent of rate.

Abstract: Monocrystalline lanthanum orthogallate grown along a predetermined crystallographic direction in the form of a single crystal of a size greater than 1 cm in diameter/width and at least 10 cm in length is described. Also described is a class of perovskite type monocrystalline compositions which are readily grown from a pure melt along a predetermined crystallographic direction. Such perovskite-type monocrystalline compositions have the following formulae:LaGa.sub.1-x Sc.sub.x O.sub.3 1.LaGa.sub.1-x Al.sub.x O.sub.3 2.LaGa.sub.1-x In.sub.x O.sub.3 3.wherein x=0.001 to 0.5. Additionally described is a class of perovskite-type monocrystalline compositions of the following formula:R.sub.x La.sub.1-x GaO.sub.3wherein R is a rare earth element of smaller ionic radius than La and wherein x=0.001 to 0.5. Further described is a class of perovskite-type monocrystalline compositions of the following formulae:R.sub.x La.sub.1-x Ga.sub.1-y Al.sub.y O.sub.3R.sub.x La.sub.1-x Ga.sub.1-y Sc.sub.y O.sub.3R.sub.x La.sub.1-x Ga.

Abstract: Devices and methods for use in integrated optics waveguide circuits containing Y-junctions are presented for intercepting and either absorbing or otherwise removing radiation which has leaked into the substrate in order that such leaked radiation cannot re-enter the waveguide circuit and cause signal errors.

Abstract: A deformable mirror construction is disclosed in which a difference in pressure between the front reflecting surface of the deformable mirror and an enclosed chamber behind the mirror's reflecting surface is used to restore the reflecting surface to its undeformed condition after its shape has been deformed by the selective operation of one or more electrodistortive actuators. A pump is associated with the chamber to produce at least a partial vacuum in the enclosed chamber. The use of a pressure differential to influence the shape of the mirror's reflecting surface avoids the need to have the actuators fastened to the reflecting surface, thereby permitting a construction which provides for the easy replacement of actuators. A preferred embodiment of the deformable mirror includes an apparatus for circulating a coolant through the mirror's faceplate to remove heat therefrom.

Abstract: A construction for electrodisplacive transducers for use in deformable mirrors in which the transducer is assembled from two or more segments of electrodisplacive material. Each segment contains multiple stacked layers of electrodisplacive material which are separated from adjacent layers by electrodes. During manufacture the segments may be individually tested and sorted by the stroke that they produce for a given electrical input signal applied to the stacked layers. Segments are selected and fastened to each other so that the total stroke produced by the selected segments equals the stroke required from the actuator.

Abstract: A coupled-cavity circuit for a microwave electron tube is shown having one or more cavities whose cross-sections are polygonally shaped, such as rectangles. Located in one or more corners of the polygonally shaped cavities are irises which have a higher resonant frequency. These irises are generally triangularly shaped with rounded corners and one leg of the triangle rounded about the drift tube of the microwave electron tube.

Abstract: There is provided a high performance extended interaction output circuit [EIOC] having two cavities. The EIOC of the present invention has an image impedance which is twice the magnitude of its output load resistance. The EIOC of the present invention also includes a three cavity EIOC which has two image impedances, the second image impedance being one half the magnitude of the first image impedance while the output load impedance of the three cavity EIOC is one third the magnitude of the first image impedance.

Abstract: An optical double-balanced quadrature mixer for analysis of optical spectra, particularly asymmetric optical spectra. Beam splitting means are used in conjunction with a quarter wavelength retardation plate to enable highly stable, accurate and precise spectral analysis. The invention is illustrated in the context of a generic light scattering test setup.