Abstract: A photodetection device including at least one element incorporating a radiation absorption layer and an unabsorbed radiation reflection layer. The absorbing layer creates a first phase shift of the reflected radiation compared with the incident radiation. According to the invention, between the absorbing layer and the reflecting layer a layer is provided creating a second phase shift, which compensates the first phase shift for obtaining a substantially flat spectral response of the device.

Abstract: The disclosure relates to a bispectral electromagnetic wave detector including at least one first and one second overlaid plane active detector elements separated by a common layer, said first and second detector elements being sensitive to the different wavelengths; a first means of connection connected in common to said first and second detector elements, a second means of connection connected to said first detector element, and a third means of connection connected to said second detector element; means for applying successively a control voltage to each means of connection; and means connected to said first means of connection to detect a photoconduction current each time a control voltage is applied. The invention is used in applications requiring detection of electromagnetic waves in two bands of different wavelengths.

Abstract: A method for providing user adjustable variable gain for a night vision device which utilizes an image intensifier tube, wherein the image intensifier tube has a given life expectancy, the image intensifier tube is subjected to factory calibration for providing an optimum output during operation, wherein the calibration undesirably differs from tube to tube and is adjustable by variable control means coupled to the tube, whereby when one tube is substituted for another the difference in calibration causes non-optimum performance, the method including the steps of: determining minimum and maximum gain limits associated with the optimum output of the night vision device; factory calibrating gain limiting means according to the determined minimum and maximum gain limits, wherein the gain limiting means are associated with the image intensifier tube and for limiting the variable control means; and, tethering the gain limiting means to the image intensifier tube.

Abstract: A night vision aid such as night vision goggles (13) is made compatable with a local full color display (17) by blocking local display light from being received by the night vision aid (13). A circular polarizer (23) of one left/right sense is positioned so as to filter the local display. A circular polarizer (25) of an opposite sense is placed before a light input of the night vision aid (13), thereby preventing the polarized light from the display (17) from entering the night vision aid (13). Advantageously, the circular polarizer (23) on the display has minimal effect on linear polarizers which may be used with eyeglasses.

Abstract: A fast power supply for an image intensifier tube used in night vision devices. The tube includes a microchannel amplification wafer placed between a photocathode and an output screen. The supply of the tube delivers a reference voltage to a first terminal of the wafer, a variable voltage to the second terminal of the wafer, a variable photocathode voltage and an output screen voltage. The illumination of the output screen is measured by its screen current. Beyond one screen value, and in order to maintain constant output illumination while avoiding dazzle, the voltage at the second terminal of the wafer is slaved to the changes in the screen current and is different from the photocathode voltages fixed. The circuit for controlling the circuit at the second terminal of the wafer includes a high voltage amplifier with transistors having small quiescent consumption and high control speed for decreasing or increasing the voltage as a function of the variations in the screen current.

Abstract: A light receiving amplifying device includes a light receiving device for outputting a light signal current which varies with a quantity of received light, a load resistor connected with the light receiving device in series, for generating a detected voltage which varies with the light signal current, and a low frequency current bypass circuit for preventing the detected voltage from being saturated when the detected voltage has a frequency in a low frequency band. The low frequency current bypass circuit is connected with the load resistor in parallel and has an input impedance varying with a frequency of the detected voltage. The device further includes a transimpedance amplifying circuit (inverting amplifying circuit) for transforming an impedance of the detected voltage, and a capacitor for coupling the low frequency current bypass circuit and the transimpedance amplifying circuit (inverting amplifying circuit).

Abstract: An optical preamplifier device for a light receiver, the device including a first optical amplifier. The first optical amplifier is coupled to an input of an optical filter centered around a fixed wavelength .lambda..sub.o via a wavelength conversion device for converting wavelength to the fixed wavelength .lambda..sub.o of the filter, thereby enabling the device to be made independent of the wavelength .lambda..sub.i of the signal.

Abstract: A semiconductor based image sensor having a timer that is associated with each photosite in the image sensor; and measuring the integration period of that photosite using the timer. Additionally, an imager sensor that does not require an A/D converter but instead uses a comparator circuit to determine when a predetermined threshold has been reached, thus reading as discrete amounts of stored charge which converts directly into a digital representation.

Abstract: A capacitive transducer which converts impulses of absorbed energy into impulses of electronic charge, combined with a unity-gain, non-inverting amplifier and an integrating capacitor which is substantially smaller than the transducer capacitance, further combined with a transconductance amplifier, comprises a simple and compact radiation detector probe. The detector probe, connected to a signal-receiving assembly through a shielded cable, comprises a useful apparatus for detecting and amplifying weak impulses of energy absorbed from X-ray photons, gamma-ray photons, or nuclear charged particles.

Abstract: A triggered optical receiver includes a single-ended or double-ended detector for detecting the optical signal and responsively transmitting a corresponding electrical signal to a first stage amplifier. The first stage amplifier output is transmitted to a triggered circuit having an input/output voltage hysteresis characteristic for identifying whether the amplified signal is a logic low or high. The hysteresis characteristic minimizes the effect of input noise and supply noise on the output. The width of the hysteresis loop may be selectively controlled to balance the sensitivity of the circuit against its noise tolerance characteristics.

Abstract: A photo detector circuit comprises a photodiode for detecting a reflected light beam from an optical recording medium and converting the light beam to a current output, and a current-voltage converter for converting the output current of the photodiode to a proportional voltage. In this circuit, the output current of the photodiode is inputted via a current mirror circuit to the current-voltage converter, so that the S/N is improved and the entire circuit can be formed into a single chip to thereby decrease the number of external elements with another advantage of dimensional reduction.

Abstract: A photodetector with a signal processing capability processes optical input signals therein. The photodetector has a first input area and a second input area which are optically isolated from each other, but electrically connected to each other due to crosstalk characteristics to operate as a two-input adder.

Abstract: An ultra-low noise, high gain interface circuit for single-photon readout of known photodetectors from the x-ray to long IR bands at video frame rates. The detector current modulate's a load FET's gate-to-source voltage, which in turn modulates the gate-to-source voltage of a gain FET thereby producing a signal current that is an amplified facsimile of the detector current. The load FET's gate-to-source voltage is connected in the negative feedback loop of a low noise, high gain amplifier. This effectively reduces the resistance seen by the photodetector by the gain of the amplifier thereby reducing the interface circuit's RC time constant by the same amount. Because the amplifier pins the load FET's gate voltage for a given flux level, the load FET's 1/f noise is transferred to the amplifier thereby enabling single-photon readout sensitivity.

Abstract: A feedback element for a two beam smart pixel receiver having at least one pair of electron devices of opposite electrical conductivity type, such as an NFET and a PFET, with input electrodes electrically connected and output electrodes electrically connected. The devices of a pair have opposing differential resistance characteristics in response to the same input signal so that the resistances of the devices of the pair add to become more linear.

Abstract: Photodiodes are situated in a row over a line segment having a predetermined width. Current generated by at least one of the photodiodes is converted into voltage by a resistor. This voltage is amplified by first MOSFETs that are connected at drains thereof in parallel to a source of voltage with a resistor between the adjacent two thereof. This voltage is amplified by second MOSFETs that are connected at drains thereof in parallel to the source of voltage. The first MOSFETs produce a first output signal that id dependent on the position at which the incident light fall on the photodiodes. The second MOSFETs produce a second output signal that is independent from the position of the incident light. A divider calculates a ratio between the first and second output signals. This ratio is indicative of information of the position of the incident light.

Abstract: An improved photodetector integrator circuit is provided having a photodetector, such as a photodiode, which produces photocurrent responsive to incident illumination. The photodetector is coupled to an integrator stage which converts the photocurrent into voltage and integrates the voltage over an integration period to provide an output signal. A window comparator in the circuit receives the output signal from the integrator stage and compares the output signal to a first threshold and a second threshold to provide, as a measurement signal, a pulse having a width which corresponds to the time interval over which the output signal increases from the first threshold to the second threshold. In the window comparator, the second threshold is greater than the first threshold.

Abstract: A highly sensitive optical receiver where one terminal of the photodiode of the receiver is connected to a negatively biased amplifier while the other terminal of photodetector is connected to a positively biased amplifier, where such connections automatically bias the photodiode and use the current from both terminals (anode and cathode) of the photodiode. This invention also provides an optical receiver which has a DC cancellation circuit to eliminate the biasing voltages in the final output signal.

Abstract: A solid-state image intensifier is provided with a thin film photoconductive layer and an electroluminescent layer which contains a polymer light emitting diode (LED) material. The photoconductive layer is a thin film which does not suffer from electrical breakdown because a low voltage is applied to the electrodes, said low voltage being sufficient to cause luminescence of the electroluminescence layer. As the photoconductive layer is thin the time response of the solid state image intensifier is shortened and its spatial resolution is improved. The color of the light given off by the polymer LED material is controlled by suitable chemical substitutions to the polymer. Consequently, the color of the light given off may be adapted to the color dependence of the sensitivity of an image sensor for detecting the output light of the solid-state image intensifier.

Abstract: A current boosted positive feedback logarithmic transresistance amplifier is provided for currency validators. The amplifier has a photo-diode capable of producing a current in response to light, connected to an operational amplifier having both a positive and a negative feedback branch. A logarithmic density amplifier having a feedback resistor and a log diode connected in shunt with the resistor as a dynamic feedback to the amplifier is connected to the positive feedback branch of the current boosting amplifier by way of the log diode. The summing action at the inputs of the current boosting amplifier result in a current at the log diode that is a direct multiple of the current in the photo-diode.

Abstract: A solid-state focal-plane imaging system comprises an N.times.N array of high gain, low-noise unit cells, each unit cell being connected to a different one of photovoltaic detector diodes, one for each unit cell, interspersed in the array for ultralow level image detection and a plurality of digital counters coupled to the outputs of the unit cell by a multiplexer (either a separate counter for each unit cell or a row of N of counters time shared with N rows of digital counters). Each unit cell includes two self-biasing cascode amplifiers in cascade for a high charge-to-voltage conversion gain (>1 mV/e.sup.-) and an electronic switch to reset input capacitance to a reference potential in order to be able to discriminate detection of an incident photon by the photoelectron (e.sup.-) generated in the detector diode at the input of the first cascode amplifier in order to count incident photons individually in a digital counter connected to the output of the second cascode amplifier.

Abstract: An array of pairs of photodetector elements is provided, where each pair intercepts a set of angularly separated light beams for each pixel, and an array of electrical logic circuits coupled to the photodetector elements, each change the polarization state of liquid crystal pixel SLM portions adjacent thereto, depending upon the intensity and presence of the light beams in each set of light beams. Thus, various Boolean logic functions may be performed at very high speeds without the need for numerous input and output electrical data transmission connections to and from the processor board supporting the SLM. This operation is facilitated by an array of microlenses affixed to the SLM for maintaining the separation of the write beams and readout beam of each set of light beams for each pixel.

Abstract: Transimpedance amplifier circuits and methods are provided in which the break frequency of the amplifier is adjusted through a single interface point to the amplifier circuit. At frequencies below the break frequency, the amplifier circuit provides an error current which effectively nulls the output of the transimpedance amplifier so that no output is produced. At frequencies above the break frequency, the break frequency setting element is essentially a short circuit that results in the frequency dependent voltage being substantially zero. This causes the transimpedance amplifier to convert current-to-voltage without signal degradation. The circuit also enables a user to adjust the break frequency without affecting the overall operation of the amplifier. Thus, the amplifier may be coupled to different output circuits for operations in accordance with different communication standards.

Abstract: A semiconductor optical amplifier having a large gain and a high saturation optical output power has a uniform cross-section of an active layer. In the semiconductor optical amplifier, the band gap wavelength of the active layer in the vicinity of the light-emitting end is shorter than that in the vicinity of the light-receiving end. The active layer may have a multiple quantum well structure, or the active layer may have a tesile-strained (compressively strained) multiple quantum well structure in which the absolute strain quantity in the vicinity of the light-emitting end is larger than that in the vicinity of the light-receiving end.

Abstract: An optical processing device for light radiation provides non-linear transfer functions in an optical guide. A coupled quantum well modulator is reverse biased by an adjustable dc voltage source through an impedance and light radiation to be processed is sent in parallel with the layers composing the modulator guiding zone. The coupled quantum well modulator has a multiplicity of layers including some which form a guide zone comprised of a sequence of alternating quantum wells and barrier layers. The light radiation to be processed passes parallel to the layers through this guiding zone.

Abstract: Optical transmit amplifier (24) fault indicator system (46), (78), and (80) indicates the failure of optical transmit amplifier (24) and includes an input loss circuit (46), an output failure circuit (80), and a modulation detector circuit (78). The modulation detector circuit (78) receives a portion (76) of the optical output signal (74) for determining therefrom that a failure in modulation exists in optical output signal (74) of optical transmit amplifier (24). The modulation detector (78) includes a modulation conversion circuit (82) and (84) for converting modulation in the optical output signal (76) into a measurable signal having a level within a first predetermined range in the presence of modulation and a second predetermined range in the absence of modulation. The modulation detector circuit (78) converts the measurable signal to a DC signal and produces a loss of modulation alarm signal (114) in response to a loss of modulation.

Abstract: A photodetector device includes a semiconductive conjugated polymer, such as PPV, arranged between first and second electrode layers having different work functions, a bias circuitry connected to apply a bias voltage between the first and second electrode layers, and a sensing circuitry connected to detect a photocurrent flowing between the first and second electrode layers across the polymer layer as a result of radiation incident on the polymer layer while the bias voltage is applied. The bias voltage is selected in relation to the thickness of the polymer layer.

Abstract: An imaging system employs a photoconductive material capable of bearing a latent photostatic image, a plurality of elongated parallel electrodes adjacent the photoconductive material, selective scanning of the individual electrodes to produce charge carriers within the photoconductive material, and time-ordered detection of the current created by the charge carriers in the plurality of elongated parallel electrodes. Dynamic rearrangement of the detection pattern for individual electrodes allows for detection from effective electrodes wider than the individual electrodes. Appropriate addressing of the effective electrodes during the scan produces a pixellated representation of the latent image having selectable resolution and reduction of edge-effect artifacts of known systems.

Abstract: A photodiode amplifier includes an input stage having a first pair of transistors connected as a differential pair to have a low input impedance and a current source connected into the input stage to bias the pair of transistors. A photodiode is connected into the input stage across the transistors so as to provide differential effect to current flowing through the transistors. By means of such connection, the photodiode is presented with low input impedance, its time constant is accordingly lowered, and the system response of the photodiode amplifier is extended into higher frequencies. The photodiode amplifier is of particular use in an illuminant discriminator capable of distinguishing a range of separate illuminants, including high efficiency fluorescent lighting within the passband of the photodiode amplifier.

Abstract: A system for compensating for positioning errors in the scanning and digital readout of latent electrostatic images on a photoconductive structure. The photoconductive structure is placed in a cassette or other holder positioned with respect to the readout scanner, which scans across the photoconductive structure in scan patterns of successive pulsed laser spots which will correspond to the pixels of the image. Elongated strip electrodes and charge amplifiers receive charge movements due to the pulse spots of the scanner. The photoconductive structure preferably has a reference strip which can be sensed by the scanner to provide a measure from a standardized Optical Start of Scan, and the Plate Start of Scan. This measurement, referred to as line skew, is a measure of the positioning errors, which will cause displacement of the scan patterns of pulse spots from their expected positions with respect to the elongate strip electrodes.

Abstract: An optical information processing element characterized by having a photoelectric and a memory layer provided with a function holding an electricity-conducting property which has been changed by radiation of light having a constant wavelength between electrodes at least one of which is provided with a light-transmitting property.

Abstract: The present invention is an image intensifier assembly that includes a Generation III image intensifier tube coupled to a single piece fiber optic inverter expander element. The single optical couple to the fiber optic expander element greatly enhances the overall performance parameters of the Gen III tube, as compared to traditional relay lens assemblies. The present invention image intensifier assembly can be directly substituted for a Generation II image intensifier tube assembly in a given application.

Abstract: There is disclosed on optoelectronic integrated circuit comprising, a plurality of channels each including an optical receiving device for converting a received optical signal to an electric signal, and an amplifier for amplifying an output signal of the optical receiving device, the channels being integrated on the same semiconductor substrate, electric power source nodes of at least two of the amplifiers of the respective channels being connected to a common electric power source node, and the common electric power source node being connected through a resistor element to an electric source power supply terminal for supplying an electric source power to the channels.

Abstract: An imaging system employs a photoconductive material capable of bearing a latent photostatic image, a plurality of elongated parallel stripes adjacent the photoconductive material, selective scanning of the stripes to produce charge carriers within the photoconductive material, and time-ordered detection of the current created by the charge carriers with the plurality of elongated parallel stripes. Appropriate addressing of the stripes as they are scanned produces a pixellated representation of the latent image. The system has improved output signal strength and higher resolution than known systems.

Abstract: A liquid crystal light valve has a photoconductive layer between a pair of electrodes, and a liquid crystal layer. The resistivity of the photoconductive layer at the portion which is irradiated with light is reduced by partial light irradiation. By applying a voltage between the electrodes in this state, the voltage is applied to the liquid crystal layer in the portion which is irradiated with light and the crystalline structure at this portion is changed, thereby enabling image data writing. The photoconductive layer is a laminate of an amorphous Si film and an inorganic insulating film disposed on the electrode side, which structure suppresses the carrier injection from the electrode to the amorphous Si film. The polarity of a voltage for writing image data into the liquid crystal light valve is inverted for every horizontal scanning operation. That is, writing of black portions on a white background and writing of white portions on a black background are alternately executed.

Abstract: An imaging system employs a photoconductive material capable of bearing a latent photostatic image, a plurality of elongated parallel stripes adjacent the photoconductive material, selective scanning of the stripes to produce charge carriers within the photoconductive material, and time-ordered detection of the current created by the charge carriers with the plurality of elongated parallel stripes. Appropriate addressing of the stripes as they are scanned produces a pixellated representation of the latent image. The system has improved output signal strength and higher resolution than known systems.

Abstract: A liquid crystal light valve has a photoconductive layer between a pair of electrodes, and a liquid crystal layer. The resistivity of the photoconductive layer at the portion which is irradiated with light is reduced by partial light irradiation. By applying a voltage between the electrodes in this state, the voltage is applied to the liquid crystal layer in the portion which is irradiated with light and the crystalline structure at this portion is changed, thereby enabling image data writing. The photoconductive layer is a laminate of an amorphous Si film and an inorganic insulating film disposed on the electrode side, which structure suppresses the carrier injection from the electrode to the amorphous Si film. The polarity of a voltage for writing image data into the liquid crystal light valve is inverted for every horizontal scanning operation. That is, writing of black portions on a white background and writing of white portions on a black background are alternately executed.

Abstract: Breakdown-mediated charge transfer is made to occur at the surface of a dielectric and its rate is limited by a defined dielectric polarization level and frequency for safe use in a clinical setting. Measurement is accomplished directly by an optical method and indirectly by a high frequency current detection method. The optical method is made reliable through a sealed construction technique. The quality of diagnostic readings supplied by both methods are made more reliable by a repeatable means of force application.

Abstract: A light-to-light conversion element which includes at least a photoconductive layer and a photo-modulation layer and in which light incident on these layers is reflected by a reflection layer and in which a selective reflection characteristic corresponding to color separation is given to the reflection layer. Thereby, among the light incident on the photoconductive layer and the photo-modulation layer, light having wavelength of the specific region is selectively reflected by the reflection layer, so that the write and read operation of information is performed on the selected light.