Abstract: A proximity sensing system and signal processing method are disclosed for detecting target objects from a movable vehicle while protecting against false target detection due to the presence of fog, clouds, or other aerosols. One or more target detectors are alternately disposed adjacent to one or more guard detectors so the edges of the fields of view are immediately adjacent. A collimated laser beam is projected away from the vehicle by a transmitter along an axis which intersects at an angle with the adjacent fields of view defining active areas in which the beam will be reflected from objects. Signals generated from any beam reflections to a target detector are made positive while signals generated by any beam reflections to a guard detector are made negative with respect to a threshold reference. The signals are summed in a differential amplifier and the resultant signal presented to a digital comparator.

Abstract: An optical projection apparatus is disclosed for generating a planar light beam of substantially uniform intensity from a nonplanar multi-element light source 10 projecting a beam having a generally Gaussian intensity distribution. Light from the source 10 passes through an optical integrator rod 52 having a faceted entrance face 54 and a spherical exit face 50. The spherical exit face 50 is designed to move the image 42 of the rod entrance face that would otherwise be created between the objective lens 14 and output plane 40 to a position 48 between the lens 14 and the exit face 50. In such manner, localized hot spots which may be created by the image 42 of the entrance face are substantially eliminated thereby ensuring that the entire length of the beam between the lens 14 and output plane 40 has a substantially uniform intensity distribution.

Abstract: A preamplifier circuit provides a low noise, low power buffer preamplification stage for interfacing low output impedance, low noise sensors to a readout circuit at cryogenic temperatures. The preamplifier circuit may be formed of discrete components, or it may be formed as an integrated circuit that may have a plurality of channels. Each channel includes a germanium bipolar transistor exposed to a cryogenic environment for providing voltage gain and impedance matching to interface the sensor ouptut with a multiplexer.

Abstract: Apparatus for sensing the ex(i)stence of a fire and providing a warning, if desired, with improved discrimination against the possibility of false alarms. Dual channel detectors are used, one detector being set to respond to incident radiation having a wavelength in the range of 0.8 to 1.1 microns while the other wavelength range is significantly displaced therefrom, being selected for wavelengths in the range from 14 to 25 microns. Reliability of true signal detection is further improved by the provision of separate flame flicker bandpass filters in the respective channels, these bandpass filters being set for different passbands. Circuits providing ratio discrimination, threshold detectors and delay circuitry are combined with the dual spectrum detectors and disparate flicker frequency filters to achieve improved performance.

Abstract: An interferometric sensor (10) employs a sensing optical fiber (12) and a reference optical fiber (14). The sensing fiber (12) has a coating 16 thereon responsive to radiated thermal energy while the reference fiber is shielded therefrom. Both the sensing and reference fibers are subjected to the same ambient environment so that both fibers are subjected to heating by convection or conduction in essentially the same amounts. As a result, the sensor (10) is substantially nonresponsive to convected or conducted thermal energy while being highly responsive to radiated energy, particularly in the 6-30 micron wavelength region.

Abstract: A fire detection system discriminates between a HEAT round that does not initiate a secondary fire and a HEAT round which does initiate a secondary fire. The system of the invention measures the peck intensity of a penetrating HEAT round in order to determine a secondary threshold level which is subsequently utilized to detect a resulting hydrocarbon fire. Also, the system performs a statistical analysis of the slope of the round thermal signature to determine if a secondary fire may be occurring.

Abstract: A detector assembly for reception of infrared radiation is formed as a composite structure of a detector array electrically connected by a set of contacts to a readout clip disposed on a backside of the assembly opposite a front side receiving incident radiation. Individual detectors are formed of layers of P-type and N-type semiconductor material, and are spaced apart from each other and from the readout chip by resilient electrically-insulating polymeric material which supports the detectors in their respective positions while allowing for thermally induced displacement of the detectors from their respective positions. A metallic grid on the front surface of the assembly provides a common electrical connection of the detectors to the readout chip. An antireflective coating may also be placed on the front surface of the assembly.

Abstract: A method is disclosed for forming a detector device, such as a thinned bulk silicon blocked impurity transducer infrared detector, by thinning a semiconductor substrate (10) and processing the thinned region (30) on two sides to form the detector device. The semiconductor substrate (10) is thinned to form a cavity (26) in the substrate (10). Further processing on both sides of the thinned region (30) is performed while the thinned region is still connected to the thicker substrate. The thinned region (30) is then separated from the substrate (10) upon completion of the given processing steps. The device is then mounted to a readout device (58).

Abstract: A tool (10) is used for detecting whether material (14) on a reference surface (12) has exceeded a predetermined height. The tool (10) includes a housing (32) having a bottom surface with at least one opening (34) therein for receiving the material (14) whose height is to be tested. A probe means (44) is slideably mounted within the housing (32) and has one end located in the opening (34) for contacting the material (14). A circuit (18, 22) includes a pair of contacts (30) spaced a given distance from a predetermined portion of the probe (44). An indicator (66) is coupled to the circuit for signaling that the height of the material (14) exceeds the predetermined height when the probe (44) slide a sufficient distance so that the portion thereof closes the contacts (30).

Abstract: A liquid metal ion source and alloy, wherein the species to be emitted from the ion source is contained in a congruently vaporizing alloy. In one embodiment, the liquid metal ion source acts as a source of arsenic, and in a source alloy the arsenic is combined with palladium, preferably in a liquid alloy having a range of compositions from about 24 to about 33 atomic percent arsenic. Such an alloy may be readily prepared by a combustion synthesis technique. Liquid metal ion sources thus prepared produce arsenic ions for implantation, have long lifetimes, and are highly stable in operation.

Abstract: An apparatus for use in testing IC chips on a semiconductor wafer is disclosed that allows the wafer and an electrical probe to be independently positioned and then clamped together and moved as a single unit when they are in alignment. This permits a chip on a wafer to be supplied with power and tested electronically while any desired area of the chip can be positioned in the field of view of a scanning electron microscope for examination, such as with a voltage-contrast secondary-electron detector. Use of the disclosed apparatus will greatly facilitate and simplify the testing of unbonded chips on semiconductor wafers.

Abstract: An article of manufacture includes a substrate carrying at least two coating layers, one layer being of approximately quarter wave optical thickness, the other layer of approximately two quarter wave optical thickness, with the layers alternating between a material such as a dielectric having a first index of refraction and a second material such as a dielectric having a second index of refraction lower than the first index of refraction. These layers form a filtering system which removes narrow bands of light such as laser wavelengths by efficient reflection while permitting the remainder of the light spectrum to pass through the article. The coating layers have optical thicknesses and indices of refraction appropriate to reflect more than 99% of incident light at one or more predetermined wavelengths of light in the range of about 300 to about 1,200 nanometers and to transmit a substantial amount of all other incident light in the range.

Abstract: A fire sensor can perform a sophisticated analysis of the outputs of radiant energy detectors, while minimizing size, weight, and cost, by employing a microprocessor to analyze the detector outputs. In a preferred embodiment, an Intel 2920 Signal Processor is utilized as the microprocessor.

Abstract: A direction finding system for infrared radiation includes a set of four detectors uniformly positioned about the Z axis of a cartesian coordinate system with individual ones of the detectors having radiation detection surfaces facing the Z axis and being inclined relative to the Z axis. The detectors are inclined relative to an XY plane of the coordinate system. Signals of the detectors are fed into computer storage to permit computation of the direction of a source of radiant energy relative to the Z axis based on a ratio of magnitudes of the signals of the detectors.

Abstract: A security system and method for IC circuits has at least one additional circuit element that does not contribute toward the IC's circuit function, but inhibits proper functioning of the IC in case of an attempted copying or other unauthorized use. The identity of the additional circuit elements is disguised by forming them with the visible appearance of an apparent element but with a physical modification which is not readily visible but causes them to function in a different manner, by providing different ICs with unique control codes, or both. Physical modifications not readily visible to a copyist include very narrow open circuit cuts in metallized connection lines, preferably with a focused ion beam (FIB) or laser beam; and/or disordering the lattice structure or changing the doping level of a semiconductor region, preferably with a FIB; and/or injecting electrical charge into a semiconductor region, preferably with an electron beam.

Abstract: Current flow in a transistorized series resonant inverter is switched in an inherently simple and stable manner by time integrating the difference between the electrical output and a reference and varying the switching frequency of the inverter so as to null the time integrated difference in a feedback control loop. Each transistor is on for about half the resonant period of the tank circuit so that it is cut off at or slightly after the zero-crossing of the sinusoidal collector current.

Abstract: A masked ion beam lithography (MIBL) system and method is disclosed which is considerably more compact and economical than prior ion implantation devices. An H.sup.+ ion beam is extracted from a source in the form of an angularly expanding beam, and is transmitted through two lenses that sequentially accelerate the ions to energies in the range of 200-300 keV. The first lens focuses the beam so that it emerges from a crossover point with an amplified angular divergence at least three times the divergence of the initial beam, thereby considerably reducing the necessary column length. The second lens collimates the beam so that it can be directed onto a mask to expose resist on an underlying semiconductor substrate. A series of extraction electrodes are used to provide an initial point source beam with a desired angular expansion, and a specially designed sector magnet is positioned between the extraction mechanism and the first lens to remove particles heavier than H.sup.+ from the beam.

Abstract: (Nb.sub.1-x Ta.sub.x).sub.2 O.sub.5 ("NTO") is purified of undesirable impurity elements present in small amounts by contacting the NTO in finely divided form to an extraction phase containing chloride, bromide, or iodide ions at a temperature whereat the ions react to remove the impurities into the extraction phase, and then the extraction phase is separated from the finely divided NTO. The process is particularly valuable in removing 3d impurities such as iron and titanium. The process can be carried out by liquid phase extraction, as with an azeotropic aqueous hydrochloric acid extraction from the NTO, or by gas phase reaction, as by reacting carbon tetrachloride with the NTO.

Abstract: A piezoelectric fan is comprised of two counter-oscillating flexible blades that are driven at resonance by a bimorph comprised of two piezoceramic bending elements. The fan is provided within the flow duct of a circulating gas laser. The operation of the piezoelectric fan serves to create a flow of a laser gas medium in a desired direction through the flow duct, thereby replenishing the gas medium between a pair of laser electrodes. The fan has no wearing elements, such as bearings, and requires no bearing lubricant resulting in the elimination of lubricant hydrocarbon and bearing particulate contamination of the laser gas medium.

Abstract: A mercury-cadmium-telluride photodiode array detector having a composite structure which includes a p-type HgCdTe substrate, a surface of which is implanted with n-type regions, thereby forming individual photodiodes of the array. Overlying this surface is a layer of insulating dielectric containing a buried layer of guard plate metalization. Overlying the dielectric is a layer of field plate metalization. Openings made through the field plate, dielectric, and guard plate allow for electrical contact with the individual photodiodes. The openings within the guard plate are made larger than those within the field plate. When these two plates are appropriately biased by external voltage sources, the substrate surface underlying the field plate and surrounding each diode is made to invert. The substrate surface underlying the guard plate remains at flat band potential, thereby electrically isolating the inverted surface surrounding each diode from the other inverted surfaces.