Abstract: A screening device (3) for screening exterior light (2) which illuminates a room (1), is controlled such that in the room on the one hand, user comfort with regard to freedom from dazzling and room temperature is optimal and, on the other hand, energy consumption for artificial lighting within the room or for heating and cooling the room is minimized.

Abstract: This invention provides a solution to the problem of determining how long the peak value detected for the first pulse be kept, and when should it be updated. In infrared communication, the communication distance may vary over time during the transmission. For instance in a mobile infrared telephone the users generally are moving with respect to each other. The signal amplitude changes within a very large range over time and the receiver expected to operate in this environment must also handle a large number of different communication protocols. It uses the instant signal as a basis for adjusting the threshold. The present invention is capable of accepting a wide input dynamic range of signals up to and beyond five orders of magnitude (50 dB). This is accomplished while overcoming the difficulties presented by many communications protocols, by providing a technique in which the output pulse width of an amplified photo detector input is not strongly dependent upon the input signal amplitude.

Abstract: A light level sensor for use in controlling the switching of artificial lighting. The sensor comprises a photoelectric transducer which provides an output signal at a level which is significant of the illumination level of incident light. An A-D converter and a microprocessor are located in circuit with the transducer for detecting the level of the transducer output signal and for any cyclic variation of the transducer output signal resulting from cyclic variation of the level of incident light. Further circuit means are provided for generating a sensor output signal if either (a) the level of the transducer output signal is below a predetermined level or (b) the level of the output signal is above the predetermined level and, at the same time, cyclic variations occur in the level of the transducer output signal.

Abstract: A light sensing apparatus for different control systems includes a photosensitive element which generates a light current depending on light incident thereto. A pre-circuit connected to the photosensitive element is operative for generating separate basic signals in response to the light current generated by the photosensitive element. Processing circuits connected to the pre-circuit are active simultaneously for converting the basic signals generated by the pre-circuit into conversion-resultant signals having different forms respectively. The conversion-resultant signals are outputted to the control systems respectively. At least one of the processing circuits may include an oscillation circuit which oscillates at a frequency depending on related one of the basic signals generated by the pre-circuit.

Abstract: An intelligent fiberoptic receiver (500) and methods of manufacturing and operating the same. During calibration procedures for the receiver, the optical-to-electrical conversion device (avalanche photodiode (501) or PIN photodiode) and its supporting control and monitoring circuits in the receiver module are characterized over a defined operating temperature range. Characteristic data and/or curves defining these operational control and monitoring functions over the range of operating conditions (temperature, power supply) are stored in non-volatile memory (526) such as EEPROM. During operation, an embedded microcontroller (520) together with analog to digital converters (532), digital to analog converters and other associated circuitry, dynamically control the operational parameters of the module based on the current operating conditions (temperature, power supply).

Abstract: The proposed method of temperature compensation for opto-electronic devices, more specifically opto-electronic semiconductor devices, involves operation of the device under predetermined constant conditions, where a first temperature dependent characteristic value is measured which is then compared with a comparison value determined under identical constant conditions but at a different temperature. A correction function is derived from the relationship between the characteristic value and the comparison value and used to correct the measured value obtained from the semiconductor device so as to compensate for the effect of temperature.

Abstract: A method for transferring signals from a photoreceiver array to computational circuitry in which parallel transfer amplifiers receive periodic offset correction. In a first embodiment, each transfer amplifier has a differential circuit that can be switched from a reset mode to a readout mode. In the readout mode, the voltage state at the output is responsive to first and second inputs, with the second input being connected to a source of a reference voltage. In the reset mode, the inputs are both connected to the reference voltage and the output is temporarily connected to a source of a fixed reset voltage. An offset adjustment signal is generated in response to detection of a voltage difference between the reset voltage and the actual voltage state at the output after the output has been disconnected from the source of the reset voltage. A single offset circuit is used to periodically and sequentially refresh the various transfer amplifiers.

Abstract: A night vision device having a power supply which delivers a high voltage level to its microchannel plate (MCP) through a variable resistance device. The voltage to the MCP is monitored and used to control the resistance to the variable resistance device such that the voltage on the MCP remains substantially at an established level, notwithstanding variations in the current being drawn by the MCP.

Abstract: A steering wheel shaft (103) position sensor includes a light emitter (110) fixed with respect to the shaft (103) and a pair of light detectors (111, 112) fixed with respect to the emitter (110). A disc (113) is mounted for rotation on the shaft (103) between the emitter (110) and the detectors (111, 112) and has a grey scale track extending circumferentially on the disc (113) between the emitter and one of the detectors (111), the grey scale varying from opaque to transparent to the light emitted by the emitter (110). A second, transparent track extends circumferentially on the disc (113) between the emitter and the other detector (112). The outputs of the two detectors (111, 112) are compared to provide an indication of the movement of the shaft (103).

Abstract: A laser diode controlling method for a compact disk drive in which light is radiated from a laser diode to a compact disk and a radio frequency (RF) signal is generated by the light reflected from the compact disk, the method includes the steps of converting the light output from the laser diode into a first electrical signal, detecting the level of the RF signal, generating a second electrical signal by adjusting the level of the first electrical signal on the basis of the level of the RF signal, and generating a driving current for the laser diode on the basis of the second electrical signal. Therefore, various types of compact disks can be driven based on the reflectivity thereof with respect to a laser beam.

Abstract: A photosensor circuit of the present invention comprises (i) a plurality of light receiving elements for detecting incident light; (ii) a plurality of output terminals for outputting photocurrents generated in the plurality of light receiving elements; (iii) a plurality of switches for selecting connection between the light receiving element and the output element in all combinations of the plurality of light receiving elements and the plurality of output terminals; and (iv) a shift register comprised of a plurality of nodes each controlling on/off of the plurality of switches. In this arrangement, when data of off or on is input into the plurality of nodes constituting the shift register, the switches corresponding to the nodes receiving the data of off are set to be off, and the switches corresponding to the nodes receiving the data of on are set to be on.

Abstract: Circuitry and method for transferring signals from a photoreceiver array to computational circuitry includes parallel transfer amplifiers that receive periodic offset correction and includes DC removal amplifiers. In a first embodiment, each transfer amplifier has a differential circuit that can be switched from a reset mode to a readout mode. In the readout mode, the voltage state at the output is responsive to first and second inputs, with the second input being connected to a source of a reference voltage. In the reset mode, the inputs are both connected to the reference voltage and the output is temporarily connected to a source of a fixed reset voltage. An offset adjustment signal is generated in response to detection of a voltage difference between the reset voltage and the actual voltage state at the output after the output has been disconnected from the source of the reset voltage. A single offset circuit is used to periodically and sequentially refresh the various transfer amplifiers.

Abstract: An analyzer for performing automated assay testing. The analyzer includes a storage and conveyor system for conveying cuvettes to an incubation or processing conveyor, a storage and selection system for test sample containers, a storage and selection system for reagent containers, sample and reagent aspirating and dispensing probes, a separation system for separating bound from unbound tracer or labeled reagent, a detection system and date collection/processing system. All of the sub-units of the machine are controlled by a central processing unit to coordinate the activity of all of the subunits of the analyzer. The analyzer is specifically suited for performing heterogeneous binding assay protocols, particularly immunoassays.

Abstract: An integrated photovoltaic detector includes a reference photovoltaic detector and an active photovoltaic detector in a series connection. The reference detector produces a dark current that opposes the active detector's dark current. The active detector effectively masks the reference detector from incident illumination so that the active detector produces photocurrent but the reference detector does not. The band gap of the reference detector is preferably matched to the active detector so that their dark currents are substantially matched over a temperature range. As a result, the current read out of the integrated detector at the series connection is approximately equal to the photocurrent generated by the active detector. This improves the detector's SNR, signal resolution, and useful operating temperature range.

Abstract: A solid-state radiation detector, including a photodiode array, is suitable for use in computed tomography, with the dark current of the photodiodes being compensated. The compensation is accomplished by an adjustable voltage source connected to the photodiode, the voltage of the adjustable voltage source being set by a regulator so that the dark current becomes zero. The regulator receives a signal corresponding to the dark current from a measured value transducer in the form of a current-driven voltage source. The voltage supplied by the adjustable voltage source to the photodiode is maintained constant while x-rays are incident on the overall detector which cause illumination of the photodiode.

Abstract: Disclosed is a photodetector comprising at least one photosensitive diode and at least one read circuit enabling the charges generated by photoelectric effect in said diode to be converted into a voltage information element sampled by a switch, wherein said photosensitive diode has a first terminal connected to the gate and to the drain of a first transistor and a second terminal connected to the source of said first transistor and to the ground of said photodetector, wherein a second transistor with dimensions proportional to those of said first transistor is mounted as a current mirror with respect to said first transistor and wherein an integration capacitor is connected to the drain of said second transistor so as to collect said voltage information element at its terminals.

Abstract: It is an object of present invention to provide a low-cost photoelectric conversion module in which a signal for compensating noise caused by changes in temperature and variations in power supply is obtained. In the photoelectric conversion module according to the present invention, a first amplifier having an input terminal connected to the anode of a light-receiving element for converting an optical signal into an electrical signal amplifies the electrical signal to obtain an amplified signal. A second amplifier having an input terminal connected to one electrode of a capacitor outputs an amplified signal for compensating noise of the electrical signal amplified by the first amplifier. The other electrode of the capacitor is connected to the cathode of the light-receiving element. The capacitor has a capacitance value equal to the capacitance of the light-receiving element.

Abstract: A light receipt system has a bias circuit and a light-receipt element. The bias circuit controls light input power to the light-receipt element to the optimum multiplication factor. The bias circuit of the light-receipt element has a first resistor, a second resistor, and a third resistor. The first resistor and the second resistor are connected in parallel, and the light-receipt element is connected between a connection of the first resistor and the second resistor, and the third resistor. A bypass current path is provided, connected to a junction point between the first resistor and the second resistor.

Abstract: The disclosed invention is a photoelectric sensor that is capable of resolving difficult low contrast sensing tasks by adjustment of the sensor's light source intensity, so as to prevent dark state saturation and extend the overall dynamic range of the sensor. The photosensor utilizes an enhanced dynamic (EDR.TM.) control circuit that combines the light source and offset adjustment of the DC amplifier circuit in a closed loop configuration. This connection provides an automatic reduction in the light source intensity as required to avoid saturation. Further, this is accomplished without sacrificing amplifier gain, so that the dynamic operating range of the photosensor is extended to include proper operation at very bright light levels. The EDR control circuit also includes an indicator circuit that is connected to the light intensity control circuit.

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 charge transfer device is disclosed. The charge transfer device has: a charge transfer section for outputting a signal charge; a voltage signal output circuit for converting the signal charge into a voltage and outputting a voltage signal; a reference signal output circuit for outputting a reference signal of a predetermined voltage, the reference signal output circuit having a circuit constant substantially equal to a circuit constant of the voltage signal output circuit; and a differential operational amplifying circuit for amplifying a difference between the voltage signal from the voltage signal output circuit and the reference signal from the reference signal output circuit and outputting the amplified difference.

Abstract: A touchless switch using a single detector to measure ambient energy and reflected energy. The detector can detect objects in both the normal unsaturated ambient energy state or when ambient energy is saturating the detector. Discrimination between toggle motion and motion which is not intended to indicate a switch toggle operation is also provided. The detector and the emitter are mounted to a circuit board which is then mounted within a housing which has a window that allows passage of ambient energy and reflected energy. A barrier between the detector and the emitter blocks energy from being directly transmitted from the emitter to the detector. The barrier may be inserted into a groove in the window to prevent energy from the emitter from being reflected off of the inner surface of the window to the detector. Accidental triggering by ambient energy is prevented by requiring that the reflected energy be detected for a minimum amount of time.

Abstract: An apparatus for detecting a light signal is provided which includes a first frequency source for generating a clock signal having a fixed frequency, a light emitting portion constituted of at least a light emitting element which is driven based on the clock signal of the first frequency source and emits a light signal, and a light receiving portion disposed apart from the light emitting portion.

Abstract: A bias circuit for applying a bias voltage to an avalanche photodiode APD2 for detecting light comprises a first diode APD1, a power supply V.sub.H connected to the first diode APD1, for applying a voltage to make the diode in breakdown between an anode and a cathode of the first diode APD1, and a constant voltage circuit V2 connected to the avalanche photodiode APD2 for detecting light, for applying a voltage difference of a breakdown voltage generated between the anode and the cathode of the first diode APD1 minus a constant voltage to the avalanche photodiode. The constant voltage is substantially independent from current flowing in the avalanche photodiode APD2 for detecting light to the avalanche photodiode.

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 photodetecting circuit using an avalanche photodiode of the present invention has an avalanche photodiode, and a bias control means for applying a bias voltage to the avalanche photodiode to drive the avalanche photodiode at a high multiplication factor. The bias control means has a diode having the same temperature dependence of a breakdown voltage as that of the avalanche photodiode, and a control circuit for applying positive and negative potentials with respect to the ground potential between the anode and the cathode of the diode such that the diode is set in a breakdown state at a predetermined current. A positive or negative potential is applied from one of the anode and the cathode of the avalanche photodiode as a bias voltage, and a photocurrent is output from the other terminal of the avalanche photodiode.

Abstract: A second harmonic generating method and apparatus is disclosed in which temperature of the nonlinear optical device is detected using a temperature sensor and the light output control is performed only when the temperature of the nonlinear optical device falls within a predetermined range through a comparison with a set temperature, so that the best peak can be selected. At no time is a different peak selected when the characteristics or operation conditions of the nonlinear optical device change.

Abstract: A pulse light-receiving circuit includes a pair of preamplifiers made up of the same circuit components, a difference amplifier for amplifying the outputs from the preamplifiers, and a pair of peak value-detecting circuits made up of the same circuit component for obtaining the amplitude of an input pulse signal. The median of that amplitude is used as a reference voltage for comparison with an output from the difference amplifier.

Abstract: A photodetector circuit is disclosed which can extract a carrier frequency signal from an optical beam. A photodiode is back-biased by a voltage supply, and the capacitance of the photodiode is dependent on the value of its back-bias potential. The photodiode is connected in parallel resonance with an inductor, and the parallel resonant combination is connected to the input of an inverting amplifier having a feedback capacitor. This feedback capacitor causes a capacitive component to appear in the input impedance of the amplifier which combines with the photodiode capacitance and the inductor to provide a parallel resonant tank circuit. The amplifier has a change in gain versus change in power supply characteristic. By selecting the value of the feedback capacitor, changes in the capacitive component of the input impedance are equal and opposite to changes in the capacitance of the photodiode, and the resonant frequency of the tank circuit is thereby essentially unaffected by changes in the supply voltage.

Abstract: A system for photoelectrically sensing the color of an object includes two or more light sources having different characteristic ranges of chromaticity and one primary photosensitive element which receives light from the light sources after it has reflected off of the target object and a secondary photosensitive element which receives light from the light sources prior to reflection off of the target. A divider element divides the output of the primary photosensitive element by the output of the secondary photosensitive element to automatically align the signal representative of the color of the object for variation in the light power output of the light sources. In an alternate embodiment, the output of the secondary photosensitive receiver is used as a closed loop feedback signal to regulate the light power output of the light sources.

Abstract: Method for compensating an output signal of a photoelectric sensor having a drift due to aging a drift in temperature and a signal in absence of optical excitation (dark signal), in an electrical proportional remote control apparatus of the manipulation or analog type comprising an actuation member or actuation part for progressive displacement functionally associated to at least one photoelectric sensor adapted to generate an electrical signal of which one parameter is representative for the displacement and/or the position of said actuation member.

Abstract: A fiber-optic system includes a photodetector for receiving optical signals from a light source, a threshold producing circuit coupled to the photodetector, and a delay block coupled to the photodetector. The threshold producing circuit produces a decision threshold voltage in response to signals from the photodetector. The delay block, formed of one or more stages of all-pass filter, delays the signals from the photodetector. The outputs of the delay block and the threshold producing circuit are connected to the inputs of a comparator. By providing a delayed signal, the decision threshold voltage is established in the comparator before the delayed signals reach the comparator. In this manner, pulse width distortion is largely eliminated in the first bit of data in burst mode data and the dynamic range of the overall system is preserved. In some cases, a multi-staged delay causes DC offset error in the delayed signal to the comparator.

Abstract: Corrective factors are applied so as to remove anomalous features from the signal generated by a photoconductive detector, and to thereby render the output signal highly linear with respect to the energy of incident, time-varying radiation. The corrective factors may be applied through the use of either digital electronic data processing means or analog circuitry, or through a combination of those effects.

Abstract: Disclosed is a picture information memory device, including a picture information memory means for generating electric charges corresponding to the intensity of write-in light incident thereon, and for holding the generated electric charges as polarized charges, an exposing means for exposing the picture information memory means to light from an object, and an alternating-current bias voltage applying means for applying an alternating-current bias voltage having a desired frequency to the picture information memory means, whereby electric charges generated by the portion of the object light the intensity of which varies at the same frequency as that of the alternating-current bias voltage, are selectively accumulated from the entirety of electric charges generated by the object light incident on the picture information memory means, and held as the polarized charges in the picture information memory means.

Abstract: Light intensity detecting circuits using reverse biased photodiodes are disclosed. Two photodiodes are fabricated with essentially the same structure in close enough proximity to each other on a single semiconductor substrate so that they both experience the same environment. In one scheme the cathode of the first photodiode is common with the anode of the second photodiode and an inverting terminal of an operational amplifier with negative feedback. A negative voltage is applied to the anode of the first photodiode and a positive voltage of the same magnitude is applied to the cathode of the second photodiode. The output of the operational amplifier is proportional to the incident light provided the intensity on each photodiode are proportional to each other. In another circuit one of either the anodes or cathodes of each diode is common and the other is input into the inverting terminal of a separate operational amplifier.

Abstract: The gain uniformity of sealed microchannel plate image intensifiers (MCPIs) is improved by selectively scrubbing the high gain sections with a controlled bright light source. Using the premise that ions returning to the cathode from the microchannel plate (MCP) damage the cathode and reduce its sensitivity, a HeNe laser beam light source is raster scanned across the cathode of a microchannel plate image intensifier (MCPI) tube. Cathode current is monitored and when it exceeds a preset threshold, the sweep rate is decreased 1000 times, giving 1000 times the exposure to cathode areas with sensitivity greater than the threshold. The threshold is set at the cathode current corresponding to the lowest sensitivity in the active cathode area so that sensitivity of the entire cathode is reduced to this level. This process reduces tube gain by between 10% and 30% in the high gain areas while gain reduction in low gain areas is negligible.

Abstract: An optical sub-system is disclosed which includes an embedded digital processor for providing continuous monitoring and adjusting of various operating parameters associated with the sub-system. The ability to modify various parameters such as bias voltage, optical signal power, etc., as a function of changes in the environment (e.g., ambient temperature, device age, power supply) results in optimization of the sub-system. The digital processor is initially programmed during environmental testing in manufacture to provide a memory associated with the digital processor which includes the optimal values for a preselected set of operating parameters as a function of various environmental conditions.

Abstract: In a signal processing circuit, a height arithmetic circuit obtains a measured value of a height of an object by using the principle of triangulation from a second light receiving signal which is transmitted from a second photodetector of position detecting type thereto. An error arithmetic circuit acquires a measurement error by using the principle of triangulation from a first light receiving signal which is transmitted from a first photodetector of position detecting type thereto. A correction circuit calculates a correct height of the object by subtracting an output signal of the error arithmetic circuit from an output signal of the height arithmetic circuit.

Abstract: A technique for performing background suppression in photodiode detectors is disclosed. A first detector measures the light emitted by the source to be measured and the background light, while a second detector simultaneously measures the background light only. The value measured by the second detector is subtracted from the value measured by the first detector, and the difference represents the portion of the first detector's measured value which is attributable to the source to be measured.

Abstract: In order to reduce a change in reverse bias to a photodiode due to drift of a power supply caused by, e.g., noise, and to suppress generation of a wrong photoelectric current detection signal, a bias circuit includes a load element (4), a transistor (Q1) for receiving a current from the load element (4) at its collector, a transistor (Q2) constituting a current mirror circuit together with the transistor (Q1), a level shift circuit connected between the base of an output transistor (Q3) of the current mirror circuit and the collector of the transistor (Q1), and constituted by transistors (Q4-Q7) and load elements (R1-R4), and a photodiode (1) connected to a desired potential node of the level shift circuit.

Abstract: A catheter assembly for measuring a fluid pressure in a body cavity includes an optical converter responsive to an electrical power source for energizing a light-emitting diode which has drift characteristics which vary in response to temperature. An optical sensor is adapted to receive the light from the light-emitting diode and to provide a measurement signal indicative of the fluid pressure in the cavity. This measurement signal has undesirable characteristics related to the thermal drift characteristics of the diode. A detection circuit detects the measurement signal and provides an output signal indicative of fluid pressure in the cavity. A special filter is included in this detection circuit which has optical characteristics that substantially offset the undesirable characteristics of the measurement signal, so that the output signal is substantially independent of the temperature of the diode.

Abstract: The output electromagnetic power of optoelectric heterojunction semiconductor devices having an active semiconductor layer with a mobile charge carrier plasma is controlled by applying a microwave electric field inside the active layer by means of at least two semiconductor contacts to the active layer that are conducting to at least one type of mobile charge carrier and blocking to another type of charge carrier. An electrical signal is applied inside the active layer to transform the distribution of energies and equivalent temperature of the charge carriers of the mobile charge carriers in order to control light emission and absorption in the active layer. A modulator is disclosed with two such semiconductor contacts on the active layer in which charge carriers are optically generated. A monolithically integrated, cavity-coupled laser and modulator is disclosed in which the laser and modulator are fabricated on a common substrate and the laser is a distributed feedback laser (DFB).

Abstract: An optical transceiver is provided for transmitting a light pulse to a target and for receiving a reflected light pulse from the target. The transceiver includes a light source for transmitting a coherent light pulse which is reflected by the target along a first optical path as a reflected light pulse. The transceiver also includes a trigger signal generating circuit, coupled to the light source, for generating a trigger signal to indicate when the light pulse is transmitted. The transceiver further employs an attenuation device, responsive to the trigger signal and situated in the first optical path to intercept the reflected light pulse, for attenuating optical transmission through the first optical path inversely as a function of time from generation of the light pulse. In this manner, reflected light pulses reflected from targets close to the transceiver receive a greater amount of attenuation than reflected light pulses reflected from more distant targets.

Abstract: A smart sheet sensor control system and method compensating for degradation of an optical sensor. A reference voltage trigger level is periodically adjusted in a manner biased toward a null state indicating an absence of a sheet of paper or document in a paper location. The reference voltage trigger level is periodically adjusted by a microprocessor to always lie within a window range between the null state value and an activated state value indicating a presence of the sheet in the paper location. Since the adjustment is periodic, the microprocessor need not be a dedicated microprocessor and may be used to adjust the reference voltage trigger level corresponding to several sensors respectively sensing the presence or absence of a sheet of paper at several different locations.

Abstract: An optical power monitoring circuit in an optical data receiver. A transconductance amplifier with non-linear feedback converts averaged photodiode current into a voltage representing a logarithm of the received optical power, which may be converted into decibels referenced to a standard power (dBm). The circuit has wide dynamic range and uses matched devices to provide processing and temperature compensation.

Abstract: An optical sub-system is disclosed which includes an embedded micro-controller for providing continuous monitoring and adjusting of various operating parameters associated with the sub-system. The ability to modify various parameters such as bias voltage, optical signal power, etc., as a function of changes in the environment (e.g., ambient temperature, device age, power supply) results in optimization of the sub-system. The micro-controller is initially programmed during environmental testing in manufacture to provide a memory within the micro-controller which includes the optimal values for a preselected set of operating parameters as a function of various environmental conditions.

Abstract: The output electromagnetic power of optoelectric heterojunction semiconductor devices having an active semiconductor layer with a mobile charge-carrier plasma is controlled by applying a microwave electric field inside the active layer by means of at least two semiconductor contacts to the active layer that are conducting to at least one type of mobile charge carrier and blocking to another type of charge carrier. An electrical signal is applied inside the active layer to transform the distribution of energies and equivalent temperature of the charge carriers of the mobile charge-carrier plasma in order to control light emission and absorption in the active layer. A heterojunction semiconductor laser is disclosed with two sets of electrical contacts: one to apply pumping currents and the other to control the electric field.

Abstract: A stabilization biasing circuit is provided for an avalanche photodiode. The stabilization biasing circuit allows for a wide range of light levels to be inputted to the avalanche photodiode, while the avalanche photodiode operates under extreme temperatures. The stabilization biasing circuit also provides for an automatic gain control, thereby enabling the electrical output signal of an avalanche photodiode to be relatively constant over a large range of inputted light levels and temperatures. Absence of optical input is identified as an increase in diode noise due to avalanche breakdown.

Abstract: An optical wavelength detector includes a photoelectric device that produces a signal in response to incident light thereon corresponding to a characteristic of the incident light such as wavelength. A light source is provided that can selectively expose light to the photoelectric device. A memory device stores device characterization data that corresponds wavelength information to current ratio signals from the photoelectric device. The current ratio signals are digitized and form part of the address for the memory. In a temperature compensated embodiment, the optical wavelength detector includes means to determine a temperature dependent electrical characteristic of the photoelectric device. In the preferred embodiment this electrical characteristic is the forward bias voltage detected when a predetermined forward bias current is applied to the photoelectric device in the dark.

Abstract: A laser imaging system, such as a storage phosphor laser imaging system, includes a correction circuit for correcting laser noise in a scanned image signal.