Abstract: A miniature RF receiver in the UHF frequency band. This receiver design is specific to the implementation of a digital module, as it contains no downconversion elements, and provides the capability of defining the operational frequency with cascaded tunable filter stages. The tunable filters are combline filters with tuning varactor diodes terminating each printed resonator. The 1 dB bandwidth of the filter is 7 Mhz, and for resonator length of 31 degrees (at the center frequency), the filter bandwidth remains nearly constant across the tunable frequency range. The capacitance of a varactor diode is a function of applied voltage. By controlling the voltage to each varactor, the filter response can be tuned across the operational frequency range of 50 Mhz.

Abstract: Chitosan-based electro-optic elements are disclosed. An optical waveguide is made from films of chitosan-acetic acid, and from films of chitosan-acetic acid doped with various rare-earth metal ions, over a substrate. Optical limiters are made from chitosan gel host materials doped with a variety of photo-interactive or light limiting dopants. Three different suitable example chitosan gel hosts are disclosed. An electrostatically self-assembling multilayer film is made with a chitosan base layer.

Abstract: An apparatus for measuring optical density of highly absorptive materials in which a beam splitter divides light from a laser source into a reference beam, which is directed to a reference detector, and a sample beam, which is reflected off a diffusing plate, through a light limiting aperture, and to a sample. The emanations from the sample are directed to a sample detector. An instrumentation amplifier compares the intensities of the two detectors. The aperture and reference detector are positioned so that the measured intensities are equal, and the optical density of the sample is calculated.

Abstract: A device which can be used to test heavy coil springs, which is of simple low-cost construction, but which is so designed that the spring can be readily mounted thereon for testing and can be readily removed when testing is completed, and will effectively retain the spring in proper position during testing, using: two containment plates, a cage made of 5 rods that pass through equi-distributed holes in the plates to contain a spring under test, and a central push rod which passes through the center of the assembly to move the containment plates together or apart as required to test the spring. A conventional spring test gauge may be fixed to either the push rod of one of the containment plates to measure the pressure generated by the spring during the test. The containment rods form a cage that expands as the containment plates compress the spring to permit the testing of long springs, and for safe testing of all springs.

Abstract: Provided are novel, electropolymerizable monomers of the formulae: ##STR1##

Abstract: A method of determining the carrier concentration depth profile in n-type wide bandgap semiconductor wafers is disclosed. The method includes placing a semiconductor wafer within a photoelectrochemical capacitance-voltage measurement system, in contact with a Schottky electrolyte solution. A high energy ultraviolet light is directed through the electrolyte solution to impinge upon the surface of the semiconductor wafer. The ultraviolet light has an energy greater than the energy bandgap of the semiconductor material and thus facilitates reliable etching thereof. The etch is allowed to continue until a desired depth in the sample is obtained. Upon cessation of the etch, the carrier concentration is determined. The steps of determining the carrier concentration and etching are repeated until the desired carrier concentration depth profile has been obtained.

Abstract: A method for making a magnetoresistive sensing device including depositing an ultrathin active film responsive to changes in magnetic field energy onto a compliant layer of periodic table group III-V semiconductor material on a semiconductor substrate wafer, the compliant layer being capable of retaining strain energy resulting from the layering semiconductor materials with different lattice constants. This method produces a battery operable ultrathin device highly sensitive to changes in magnetic field flux.

Abstract: An at least semiconductive polymer film is provided by infiltrating novel rigid-rod heterocyclic polymer film containing a 2,2'-bipyridine-5,5'-diyl moiety, with a conductive metal salt. These polymers have repeating units of the formula ##STR1## wherein Z is selected from the group consisting of ##STR2## wherein Q is --H or --C.sub.6 H.sub.5. Alternatively, the metal salt in the semiconductive polymer film can be reduced.

Abstract: The invention comprises devices composed of at least one microscopic hollow tube having a wall of single or multiple layers with a thickness of at st one nanometer and a diameter of at least 5 nanometers. The walls of the tubes can be formed from a wide variety of materials, some of the preferred materials include metals, polymers, carbon, ceramics, glasses. If the space between the tubes is filled, the tubes become channels in a monolithic or composite body. The channels can have a random or ordered orientation. The interior of the tube walls can be coated with a desired material such as a catalyst and also may have depressions or elevations therein that were imparted to the fibers upon which the tubes are formed. The wall layers may be porous for the purpose of removing the fiber therethrough. Microtubes and microtube devices may be interfaced with the macroscopic world in a number of ways.

Abstract: A one-laser technique for optical time-delay beamsteering of a microwave phased-array antenna in transmit-and- receive modes. Arrays of reflective, fiber Bragg gratings are employed and a modulated, wavelength-tuned laser excites prism-shaped arrays of chirped or single-frequency gratings deployed inside a set of N parallel fibers. The fiber gratings can be replaced by waveguided gratings within a semiconductor chip for operation at high microwave frequencies.

Abstract: A thin membrane is mounted on an optically flat circular outer ring and stretched over a smaller optically flat circular inner ring. Differential pressure is applied to the annulus formed between the inner and outer rings to prestrain the membrane and separately applied to the inner ring where the mirror figure will be produced. The inner ring has a doubly curved top surface and is optically fiat so that the membrane can freely move across the inner ring as incremental stress is applied via the annulus. A calculated combination of annulus stress and differential pressure on the inner ring produces an optical quality mirror figure in the inner ring area.

Abstract: Using a GaN growth furnace, at least three different techniques can be used for forming the targets for the deposition of thin films. In the first, nitrides can be deposited as a dense coating on a target backing plate for use as a target. In this approach, the backing plate is placed near the Group III metal. During processing, the Group III metal or metal halide vaporizes and reacts with the nitrogen source to deposit a dense polycrystalline layer on the backing plate. To build up a thick layer on the backing plate, the backing plate is repeatedly placed in the processing furnace until a satisfactory thickness is attained. For the second approach, a properly shaped reaction vessel, the dense, thick Group III nitride crust that forms on top of the Group III metal during the process can be used directly or mechanically altered to meet the size requirements for a sputtering target holder.

Abstract: A magnetically suspended door is described for the protection of spacecraft instrumentation exposed to space. The door is slid between an opened or closed position using electromagnets.

Abstract: The purpose of the nonlinear spectrophotometer is to provide a simple instrument that can be used on a routine basis to accurately measure the two-photon absorption (TPA) coefficient and cross-section on a wide variety of materials. The instrument is capable of measuring: (1) both organic and inorganic materials, (2) solutions and thin film materials forms, and (3) materials which are fluorescent and nonfluorescent.

Abstract: Large space-based optical systems are expected to produce optical beams with large wavefront phase aberrations due to their size, weight limitations, optical misaligments and primary mirror imperfections. The present invention combines a phase diversity wavefront sensor with a real-time programmable two-dimensional array of liquid crystal variable retarders for wavefront correction.

Abstract: A method for vibration damping cylindrical members is described which comprises applying constrained damping treatment, in the form of narrow strips of damping tape, to the surface of the member in a helical (barberpole) configuration at a selected pitch angle to a generator line of the member, the tape being either continuous (unsegmented) or segmented at selected optimal length.

Abstract: A method for fabricating a fiber reinforced composite bridge module is described which in one preferred embodiment includes the steps of selecting a cross-sectional shape for the bridge module defined by an outer substantially tubular shell having a top side and a bottom side, and a floor deck near the bottom side and at least one keel beam beneath the floor deck and extending lengthwise of the outer shell, the outer shell, floor deck and keel beams defining a plurality of passageways along the length of the module, winding fiber and impregnating material on mandrels in a plurality tubular sections defining the plurality of passageways, joining the plurality of tubular sections in side-by-side relationship in an assembly substantially defining in cross section the cross-sectional shape of the module, winding fiber and impregnating material around the assembly to a preselected thickness for the outer shell; and curing the fiber and impregnating material.

Abstract: A multi-octave bandwidth antenna is disclosed which radiates with variable polarizations using: a metal ground plane, first and second blade antenna elements, first and second coaxial transmission line feeds, and a 180.degree. hybrid coupler. The two blade antenna elements are fixed above the metal ground plane in proximity with each other, and fed respectively by the central conductors of the first and second coaxial transmission line feeds. The 180.degree. hybrid coupler has a sum and difference port to control the polarization of waveforms of the antenna.

Abstract: A new apparatus for displaying and recording an image viewed by a marksman or shooter through a weapon sight is described. A beam splitter is mounted at the eye end of the weapon sight and bends part of the image intended for the shooter 900.degree. to a righting prism which bends the image another 900.degree., for a total of 180.degree.. The image from the righting prism is directed to the input of a miniature video camera mounted over and parallel with the weapon sight. The video camera transmits the image to a remote miniature video display and to a remote video recorder. By bending the image a total of 180.degree., the video camera can be mounted in a low profile position over the weapon sight such that the overall balance of the weapon is minimally upset.

Abstract: A process for treating industrial waste water containing hexavalent chromium (Cr.sup.+6) and other heavy metals is disclosed which comprises reduction of Cr.sup.+6 to trivalent chromium (Cr.sup.+3) and the precipitation thereof with other heavy metals by addition of sulfide ion and ferrous ion to the waste stream at a pH of about 7 to 9 under conditions such that sludge production by the process of the invention is substantially less than that characteristic of prior art processes. Polymers are added to the solution to assist flocculation and clarification of the waste stream. More specifically, the invention comprises adding sulfide ion in a sulfide to hexavalent chromium ratio of about 0.7-2.5:1 and adding ferrous ion in a ferrous to hexavalent chromium ratio of about 0.5-5.0:1. The waste stream pH is preferably maintained in the range of about 7.2 to 7.5.