Abstract: A color filter which, in a reflection type color picture projector using a polarized light component as a projection light, improve the utilization factor of light and a color picture display device using the same color filter are provided. The color filter 3 using a transmission type hologram diffracts and spectroscopically separates P polarized light components related to respective primary colors and condenses them to pixel electrodes 13r, 13g, and 13b on the side of an LCD panel 1. A reflection light which is modulated by an optical modulator 16 on the side of the LCD panel 1 and becomes S polarized light component is incident on the color filter 3. The color filter 3 transmits the S polarized light component and uses it as the projection light.

Abstract: A bandpass filter having 4-degrees of freedom includes a plurality of resonant cavities having respective Qs where at least one of the Qs is different. A plurality of main couplings couple successive resonant cavities to establish a main signal path that provides a first degree of freedom for controlling the shape of the filter's frequency response over its passband. A plurality of bridge couplings couple pairs of the resonant cavities so that the cavities are connected in a canonical circuit topology. The bridge couplings provide second and third degrees of freedom for controlling the sharpness of the frequency response 's transition between its passband and stopband and controlling the linearity of its phase, respectively. The cavities' non-uniform Qs provide a fourth degree of freedom for controlling the amplitude of the filter's frequency response in the passband so that the amplitude is within a predetermined tolerance of a desired passband shape.

Abstract: A remote ground terminal for transmitting a modulated data signal to a satellite. The remote ground terminal comprises a source of data signals, a demodulator for receiving a data signal and coupling the data signal to a transmitter, and for producing a power control signal during the period the data signal is present at an input of the demodulator. The power control signal is coupled to the transmitter and controls the operation of the transmitter such that the transmitter only receives power when the demodulator produces the power control signal. During the period the transmitter receives power, it functions to provide and modulate a carrier signal in accordance with the data signal received from the source of data signals.

Abstract: A passive intermodulation shield (10) for a spacecraft is made from a substrate (12) and a vacuum deposited aluminum layer (14) over the substrate (12). The substrate (12) can include a polyimide sheet such as Kapton. The vacuum deposited aluminum layer (14) has a thickness (16) to produce a surface resistivity which maintains both the inherent passive intermodulation generation and the passive intermodulation passthrough below a predetermined value. Preferably, the surface resistivity is selected between 10 ohms per square and 40 ohms per square. Spacecraft multilayer insulation blankets (30, 40, 50, 60) are formed by disposing the passive intermodulation shield (10) between a pair of outer layers.

Abstract: A bandpass microwave filter (32) is constructed by use of a right cylindrical cavity resonator (10) wherein end regions (22, 24) of the resonator are tapered. The tapering is accomplished by replacing end portions of a right cylindrical sidewall with frusto-conic sections (22, 24) of side wall. Each frusto-conic section joins a central cylindrical section (26) of the sidewall with a planar end wall (14, 16). Each of the end walls is provided with a coupling slot (28, 30) having dimensions substantially smaller than a half wavelength of the center resonant frequency of the resonator so as to be a nonresonant slot. The slots in the end walls may be coupled to rectangular waveguides (34, 36) which form input and output ports by which electromagnetic signals are applied to and extracted from the resonator.

Abstract: Input RF signals to a transponder, such as a communications satellite, are down converted to a lower intermediate frequency (IF) that is common for each different channel. The channel signals are all processed at the common IF, and then up converted to different respective transmission frequencies. This allows for a down conversion/signal processing/up conversion unit design that is the same for each channel (except for frequency and gain values), and facilitates the use of inexpensive available standard components as well as low bandwidth channel filters. An improved phase noise cancellation phase lock loop (PLL) is preferably used to generate tuning signals used in the up and down conversion processes. The PLL includes two loop mixers, with the down and up conversion mixing signals taken respectively from the inputs to the first and second loop mixers. The first and second loop mixers receive mixing signals at frequencies (T-R) and (T-IF-N.multidot.

Abstract: A split Stirling cycle type of cryogenic cooler (10) includes a compressor portion (12) and an expander portion (14). The expander portion (14) is of the "cold finger" type, and is configured to operate in near-resonance with the characteristic cyclic operating rate of the compressor portion (12). As a result, an improved performance of the cooler results both during cool down from ambient temperatures and after cool down. Additionally, a quiet operation of the cooler is provided both during and after cool down to cryogenic temperatures.

Abstract: A method and apparatus for adjusting the postamble false detection probability threshold for transmission systems that carry telephony network signals using binary-phase shift-keying (BPSK) burst transmission format. The postamble marks the end of a burst transmission. The method and apparatus herein classifies the type of signal present on the telephony network and utilizes a control loop to change the threshold, if necessary, to minimize the probability of false detection of the postamble during demodulation. Transmission of speech signals, which are bursty in nature, suffer little degradation from false detection of a postamble. However, transmission of fax, voice-band data modems and other types of longer-duration signals are severely affected by a false detection of the postamble unique word. Therefore, fax, modem and other longer duration signals have their threshold adjusted to minimize the false detection probability after the signal has been classified as such.

Abstract: A circuit and method for puncturing data on the transmission side of a digital communications system. The puncturing circuit includes a multiplexer circuit that receives a data stream and a delayed version of the data stream. The multiplexer circuit generates a multiplexer output which can be either a bit from the data stream or a bit from the delayed version of the data stream. A control circuit is coupled to the multiplexer circuit to select which multiplexer input appears on the multiplexer output. The control circuit selects the multiplexer output according to a predetermined puncture pattern. The control circuit may be a counter coupled to a decoder which is coupled to the multiplexer. The decoder may be specially designed to decode the predetermined puncture pattern and rate, and the counter controls the decoder's movement through the puncture pattern and rate.

Abstract: The carrier opener system has a channel and guide pins for retaining and accurately positioning a carrier which has a component captured therein. A driver moves from a first to a second position and moves a carriage from a first to a second position where guide pins positively locate the carrier and release fingers enter the carrier. Motion of the driver from the second to the third position does not move the carrier, but moves the release fingers to engage in the carrier to uncaptivate the component for its subsequent removal. In this way, a carrier is accurately positioned and its component is precisely released.

Abstract: A wireless train proximity alert system provides a constant warning signal to warn vehicles approaching a train crossing when a train is also approaching the crossing. The system includes a transceiver, positioned on the train itself or at the side of the track, for transmitting a train proximity signal, which preferably includes the train's speed and position. A crossing-based transceiver receives the train's proximity signal and transmits the boundary coordinates of a warning zone when the train's estimated time-to-arrival at the crossing is within a predetermined range. A vehicle-based receiver receives the warning zone signal and the crossing's position, compares them to the vehicle's position and speed, and produces an alarm to the vehicle's operator when a potential accident is indicated.

Abstract: An improved transponder for transmitting an identification of an animal or the like is described which is sufficiently miniaturized to be syringe-implantable, thus avoiding the necessity of surgical procedures. The transponder comprises a coil which receives an interrogation signal and transmits an identification signal in response thereto. The transponder receives the energy required for transmission by inductive coupling to an interrogator. A single integrated circuit chip is provided which detects the interrogation signal, rectifies it to generate power needed for transmission, stores an identification of the transponder and hence of the animal in which it is implanted, and generates a frequency-shift-keyed, Manchester encoded identification signal in response to the interrogation signal. The device transmits the identification signal in real time, that is, immediately upon commencement of the interrogation signal, such that no discrete elements for energy storage are required.

Abstract: A method of forming a polymer dispersed liquid crystal (PDLC) film is disclosed which consists of forming a solution of LC dissolved in a monomer, photopolymerizing the solution to form a film having a dispersion of LC bubbles therein, establishing a correlation between the LC bubble size and selected characteristics of the film, selecting a LC bubble size corresponding to desired film characteristics, and controlling the conditions of photopolymerization to achieve said LC bubble size. The LC bubble size is controlled by means of the UV exposure intensity, exposure temperature, exposure wavelength, LC concentration and/or concentration of polymerization initiator. Correlations are noted between LC bubble size and the resulting film's threshold and operating voltages for optical transmission, contrast ratio, absolute transmissivity and electro-optical response times.

Abstract: Uniform electrical heating of a circular, single crystal germanium window (18) uses its bulk resistance and pairs of electrodes (20) equally spaced about the window's periphery. The electrode pairs are sequentially switched at a rate high enough to avoid thermal switching transients.

Abstract: A Raman laser (10) is provided using a pump laser (22) as a source of radiation at a first wavelength and a Raman cell (30) for converting the first wavelength radiation to a second wavelength. The pump laser (20) provides polarized radiation at a predetermined first wavelength which is focused by a focusing means (40) into a Raman medium (32) which converts radiation at the first wavelength to a predetermined second wavelength by Raman scattering processes. A reflection means (50) which is aligned normal to the first wavelength radiation is disposed between the pump laser (20) and focusing means (40). The reflection means is substantially 100% reflective of radiation at the second wavelength and substantially non-reflective of radiation at the first wavelength.

Abstract: A CO.sub.2 TEA laser Q-switch uses an intra cavity rotating prism (70) with internally reflecting surfaces (76, 78) at near the critical angle to produce a variable optical loss such that the gain of the laser is switched as the prism rotates through the critical angle. The nitrogen tail portion of the laser output pulse can be eliminated by switching the gain just after the main pulse at the beginning at the tail. An opto-electronic timing device (100), which includes a graded index glass rod (101) rotating with the Q-switch prism, generates a pulse (88) to initiate the laser discharge at the proper lead time before the prism switches the resonator gain.

Abstract: A soldering flux, method for fluxing pieces, and method for joining pieces, wherein hydrofluoric acid or an evaporative organic acid is mixed with an evaporative organic solvent to form the flux. Neither precleaning nor postcleaning of the pieces being joined is necessary. The flux evaporates completely upon heating, leaving no corrosive residue or other product on the surface of the piece. The portion of the piece to be bonded is dipped into the flux and immediately tinned, before soldering.

Abstract: A differential phase shifting structure is disclosed, employing corrugated ridges in square or round waveguides or in coaxial lines operating in the TE.sub.11 mode. The structure provides a substantially constant differential phase shift between two waves polarized orthoganally to each other. The corrugations in the ridge provide a series inductance which can be optimized with the shunt capacitance of the ridge to provide a characteristic impedance matching that of the unloaded structure. The corrugated ridges provide increased differential phase shift per unit length. The differential phase shifting structure is particularly well suited to such applications as circular polarizers, quarter wave plates or polarization rotating half-wave plates.

Abstract: An imaging system incorporating a scanned array of infrared detectors for a presentation of scene data on a display includes gain normalization circuitry coupled to individual ones of the detectors of the detector array. The normalization circuitry is structured as a feedback loop introducing equality between the magnitude of an average value of a detector signal and a reference signal. The imaging system comprises a set of channels connecting with respective ones of the detectors, each channel having adaptive gain control circuitry. A common value of the reference signal is applied to each channel for uniformity in a displayed image. The averaging time is several times greater than the duration of a single scan in the scanning of the detector array so that the display is relatively free of nonuniformities associated with differing responsivities of the detectors to infrared radiation.

Abstract: A method for fabricating supported fine line electrical conductors comprises the steps of forming a pattern (16) which defines a configuration (18) of the desired conductors on a surface (12), placing electrically conductive material on the surface in a configuration defined by the pattern to form electrical conductors (20), removing only the pattern from the surface and thus leaving the configured electrical conductors thereon, adhering a support (22) to the electrical conductors with an adherence which is greater than that existing between the conductors and the surface, and separating the assembled conductors and support from the surface. One of the surface and of the support and assembled conductors is flexible and the other is relatively rigid, so that the flexible one can be peeled away from the rigid other.