Abstract: Azimuthal mode control for lasers employs an optical system which rotates the image to produce an optical feedback system, which through interference with the cavity fields, supresses the unwanted modes.

Abstract: An electrostatic transducer of the type comprising electrically conductive plates and a conductive, flexible, vibratable diaphragm. The transducer may either be a flat radiator or of the folded type. The surface area of the plates is substantially smaller than that of the diaphragm. Additionally, the plates are preferably staggered to reduce both capacitance effects and the required driving power. The plates may be of different sizes to control dispersion of the sound. Instead of applying an electric bias to the structure, an electret may be used to obviate the necessity of a bias field. The transducer may be used as both a loudspeaker or a microphone. It may be driven by electric signals or partially by electric signals and acoustic waves thus forming an integrator. Finally, it may be driven solely by acoustic waves.

Abstract: This invention relates to laser fuels and, more specifically, to solid fuels suitable for use in a chemical laser.

Abstract: Disclosed is an apparatus for producing color hardcopy pictorial data recordings.A two-dimensional data frame is displayed on a black-and-white CRT screen and is ultimately recorded on a moving photographic film as a color line, which line is parallel to the horizontal dimension of the CRT screen. The vertical position and intensity of any illuminated phosphor dot in a given horizontal position on the screen determine, respectively, the hue and the intensity of the resolution element in the color line having the same relative horizontal position. The light from the CRT screen is collimated, spectrally dispersed and imaged onto an image plane containing the slit. The elements of the apparatus, including the slit, are relativey positioned so that a particular vertical position on the CRT screen will cause light of a particular color to be imaged onto the slit.

Abstract: Disclosed is an apparatus for generating a pulse train whose instantaneous repetition rate represents the instantaneous angular velocity of a rotating device.An oscillator feeds a high frequency signal to a coil through which a center pole of magnetic material projects. The rotating device causes an object such as a gear to rotate, at least a portion of the extremity of which (e.g., the tips of its teeth, in the case of a gear) repeatedly comes into close contact with the tip of the center pole, separated only by a small air gap. This results in a change in inductance of the coil, which amplitude modulates the oscillator output. The modulated output is passed through a peak voltage detector which generates the desired pulse train.

Abstract: An optics module for use in a holographic borehole instrument which is operable to determine the stress in the wall of a borehole by recording successively on the same holographic recording medium two holograms of a selected surface region of the wall and, in the interval between the two recordings, drilling a stress relief hole in the wall in stress relieving relation to the selected surface region to produce on the recording medium a double exposure hologram containing holographic information representing the stress. The optics module embodies a frame which adjustably mounts the optical elements of the holographic system of the instrument in a manner which facilitates initial alignment of the system and preserves the alignment during instrument operation.

Abstract: The lasing species of CS(a.sup.3 .pi.) and CSe(a.sup.3 .pi.) are produced by reacting atomic carbon and COS or COSe in an inert medium such as helium, argon, nitrogen, etc.

Abstract: An active attitude control apparatus for damping roll/yaw nutation motion within the control deadband of a satellite which is three-axis stabilized to local vertical by means of a pitch biased, body-fixed reaction wheel and offset roll-yaw thrusters. The apparatus is incorporated into a system in which large attitude motion outside the deadband is controlled by means of the offset roll/yaw control thrusters with an accompanying control mechanism for activating the thrusters in an appropriate direction when motion outside the deadband is sensed. The present apparatus includes logic circuitry apparatus to cause a second thruster activation, of the same sense, after each deadband actuated thruster firing, where such a firing in the same sense has not been triggered within a certain elapsed portion of the satellite nutation period, approximately 5/8ths of the period being preferred.

Abstract: 1. A correlation system for two complex multifrequency input signals which may contain relatively strong narrow band components including the combination of: auto-correlator means responsive to one of the input signals, the auto-correlator means dividing the one input signal into two channels and including delay means in one of the channels for introducing a fixed relative timing displacement between the two signals, threshold means coupled to the auto-correlator means for indicating when the auto-correlation output signal exceeds a selected amplitude, first and second delay means each responsive to a different one of the input signals and introducing like delays thereto, gating means coupled to at least one of the delay means and controllably responsive to the threshold means, and correlator means coupled to said delay means and said gating means for correlating the two input signals therefrom.

Abstract: A thick layer of silicon dioxide is grown on a semiconductive substrate and then etched to form an elongated opening that defines the outer boundaries of a diffused transistor. The thick silicon dioxide layer serves as a permanent fixed, diffusion mask. The first diffusion is performed through the permanent mask opening. Thereafter, portions of the elongated opening are masked by secondary thin layers of silicon dioxide or photo-resist, and subsequent diffusions are performed through different unmasked portions of the elongated opening.

Abstract: A heat radiating coating of rhenium for a refractory core which may be used for a rotating X-ray anode, power tube or the like. The coating is characterized by a multiplicity of needle-like radiation-reflecting elements disposed adjacent to each other. The needles have such steep angles that incoming radiation is substantially absorbed thereby by repeated reflection. Since the coating has a high radiation absorption coefficient it has a corresponding high emissivity on the order of 0.9 at elevated temperatures. A process is disclosed for depositing such a heat radiating coating of rhenium by chemical vapor deposition.

Abstract: There is disclosed a method and apparatus for measuring electromagnetic conductivity within a medium to thereby derive a measurement of the rate of propagation of a magnetic field therein. If one then measures the return time of a pulse transmitted in the medium when a conductivity anomaly is encountered which creates a reflection, a magnetic diffusion radar can be calibrated. This technique enables one to measure the conductivity of a propagation medium such as salt water, earth or the like for any desired purpose such as determining the salinity of sea water or river water. More particularly, however, this enables one to make such a measurement in order to provide an electromagnetic anomaly detector such as is used in metal locaters, mine detectors, and in geophysical prospecting or exploration.

Abstract: A digital speech compression system uses a predictive feedback loop. The digital speech signals are compressed within the feedback loop for reducing the transmitter bandwidth. The system comprises a first adder into which the digital signal is fed followed by a quantizer and a compression logic. The predictive loop includes a second adder coupled to the compression logic and followed by a digital predictive filter. The output of the filter is impressed in a negative sense on the first adder and in a positive sense on the second adder. Specifically, the quantizer and compression logic may consist of a two-valued limiter followed by a compressor and a converter in the feedback loop or alternatively the limiter may be followed by a converter while the compressor is disposed outside the feedback loop to provide sample by sample compression.

Abstract: A waveguide structure is fabricated by plating a mandrel with a high electrical conductivity metal, such as copper; plasma spray coating the plated mandrel with a selected waveguide body material; forming coupling flanges about the plated mandrel at the ends of the plasma spray formed layer; and removing the mandrel in such a way that the plated metal and plasma spray formed layers remain intact to form a tubular waveguide body with an inner high conductivity liner. The waveguide structure described is a plural cavity bandpass waveguide filter which is fabricated on a mandrel comprising separable sections arranged end to end. Plated iris discs are clamped between the confronting ends of the mandrel sections prior to metal plating plasma spray coating of the mandrel, such that when the mandrel is removed, the iris discs remain intact with and peripherally joined to the filter body liner to define the resonant filter cavities.

Abstract: A multifrequency laser oscillator which generates coherent light of two closely adjacent optical frequencies in rapid succession for recording contour holograms by the double exposure technique. The two light frequencies are selected by an optical intercavity frequency selector which is rotatable to a first position to select one frequency and to a second position to select the other frequency. The described laser oscillators have a ruby lasing medium and lase at the R.sub.1 and R.sub.2 transitions of the ruby resonant fluorescence.

Abstract: A drill module for use in a holographic borehole instrument which is operable to determine the stress in the wall of a borehole by recording successively on the same holographic recording medium two holograms of a selected surface region of the wall and, in the interval between the two recordings, drilling a stress relief hole in the wall in stress relieving relation to the selected surface region to produce on the recording medium a double exposure hologram containing holographic information representing the stress. The drill module embodies a drill which is normally retracted from the field of view of the holographic system to permit unobstructed holographic recording of the selected wall surface region and which is extended into the field to drill the stress relief hole in the interval between the two holographic recordings.

Abstract: In a parallel resonant circuit having an inductor connected in parallel with a capacitor, a sensing resistor is connected in series with the inductor to sense the current in the resonant circuit. The voltage drop across the sensing resistor is applied to an operational amplifier and the amplified output voltage is fed back to the circuit loop out of phase with the sensed voltage drop so as to reduce the effective circuit resistance and thereby increase the circuit Q.

Abstract: Monomeric high molecular weight dianhydrides or tetraacids can be produced by the nucleophilic coupling of a halo substituted phthalimides acid and an aliphatic or aromatic compound having polyfunctional groups capable of reacting with the halo moiety of the phthalinide followed by hydrolysis and dehydration. Specifically, 4-chlorophthalate sodium salt is converted to an imide to reduce side reactions with the carboxylic acid groups prior to reaction with 4,4'-disodiumdiphenylene oxide sulfone or 2,2-di (4-sodium phenoxide) propane. After the reaction of the imide and the sulfone or propane compounds, the diimide formed is converted to the corresponding dianhydride.

Abstract: A parallel or serial analog-to-digital converter utilizing both Gunn effect devices and field effect transistors. The converters are based on a differential pair of amplifiers consisting of two or more Gunn effect devices, one of which is biased close to the knee of the current-voltage characteristic before the negative resistance region. Hence a clock pulse will bias one of the devices into the negative resistance region while the other device is now biased close to the knee to be able to respond to the analog signal. This is due to the fact that both devices are biased by a common constant current source, including a field effect transistor.

Abstract: A digital speedometer, frequency or event counter with digital display. The speedometer conventionally receives speed pulses representative of the speed of the vehicle. Due to the lack of synchronization between speed pulses and clock pulses the last display digit exhibits undesirable jitter. This may also be caused by backlash in the drive train or the like. This jitter is minimized by the provision of a precounter between the counter and the gate transfer to a storage register. This will permit transfer of the number generated in the counter only if the precounter is in the zero state, thus minimizing the jitter due to random occurrences of the last pulse.