Abstract: An optical densitometer includes a receiver adapted to produce an electrical output voltage characteristic of an optical density to be measured. A voltage-controlled oscillator produces a periodic signal having an output waveform with a frequency and period characteristic of the output voltage of the receiver. A counter produces a digital value corresponding to the output waveform of the periodic signal produced by the oscillator; and a converter produces a digital optical density signal from the digital value. The counter is adapted to produce its digital value corresponding to the frequency or period of the periodic signal produced by the oscillator. The counter may include a portion adapted to produce a digital value corresponding to the frequency of the periodic signal produced by the oscillator; and a portion adapted to produce its digital value corresponding to the period of the periodic signal produced by the oscillator.

Abstract: An apparatus for receiving signals from a photodetector in a photodetector array. The apparatus has a number of comparators (e.g. 5) connected to the photodetector. each photodetector in the array has a similar circuit connected. Each comparator compares the output of the photodetector with an adjustable threshold level. Each threshold level is controlled by a threshold controller. Each threshold level corresponds with a light intensity value. Outputs of the comparators are each connected to a shift register. Each shift register is triggered to sample the output of its associated comparator at a certain speed (e.g. 800 Mhz). In operation, the shift registers each store a bit sequence representative of the comparator output. The data acquired is used to adjust the threshold levels applied to the comparators. In this way, adjustable intensity resolution is provided at desired ranges of intensity.

Abstract: A method and apparatus for measuring very low light signals including integrating a signal from a photo diode, avalanche photo diode, photomultiplier tube or the like, digitally sampling the integrator output more than two times during each integration period, fitting a curve to the multiple digitized readings to calculate the integration slope for each integration period and determining the original signal from the calculated integration slope.

Abstract: A monolithic light-to-digital signal converter (1.10) includes a photodiode array (1.24) having a plurality of sections with each section producing a current signal in response to incident light, a current-to-digital signal converter circuit (1.28) for converting selected ones of the current signals to a digital signal, and a control circuit (1.26) for scaling the digital signal in response to user supplied programming signals. The control circuit (1.26) also responds to user supplied programming signals to supply control signals to current-to-digital signal converter circuit (1.28). Current-to-digital signal converter circuit (1.28) is responsive to the control signals for combining selected ones of the current signals into a composite current signal and converting the composite current signal to a digital signal.

Abstract: Configurable Optical Gates (COGs) are used to transmit and receive optical signals similar to an interconnect device as well as perform a logic function on those signals (they are smart pixels). COGs consist of a laser with an intracavity modulator, an integrated current source and one or more integrated photodetectors to drive the modulators. The devices are monolithically integrated on MultiQuantum Well (MQW) heterostructure. Certain logic functions require that the bottom N- contact which is under individual devices be accessible and electrically isolated from neighboring devices. For this reason, the laser heterostructure is grown on a semi-insulating substrate. Each COG has a built-in light baffle that prevents the laser emission from coupling into the photodetectors. The optical detection of the COG can be disabled during fabrication and the device can be directly modulated by conventional electronics.

Abstract: A light receiving circuit provided with an amplifier for amplifying an output signal of a semiconductor light receiving element is disclosed. The amplified electrical signal is first inputted to the inverting input terminal of a comparator. An output voltage of the comparator is divided by resistors connected in series with each other. The difference voltage between the voltage applied to the inverting input terminal and a voltage being present at a connection point between the resistors is divided by means of resistors, and a voltage obtained by this voltage division is then applied to the non-inverting input terminal of the comparator. The amplitude of an output voltage of the comparator is reduced by dividing this output voltage. Moreover, the mean value of this output voltage thereof can be made to be closer to the ground potential. Therefore, when the output of the comparator has a high level, a threshold voltage to be applied to the non-inverting input terminal becomes lower.

Abstract: A stroboscope is employed as the lighting source for a video camera, the output of which is converted into a signal from which a fault in the object scanned is detected. The stroboscope is controlled in response to a portion of the output voltage of the video camera to insure that the luminous energy is constant.

Abstract: A photometer of a camera employs a MOS-type CPU having an open drain type transistor whose drain serving as an output terminal, a CMOS input terminal, and an input gate inverting an input with a value exceeding a predetermined potential. In the photometer, the transistor is set in a high-impedance state, thereby releasing a charge accumulated in a parasitic capacitor of a photodiode for generating a photoelectric current corresponding to an incident light amount. Thus, a voltage at the CPU terminal gradually increases, and, when it exceeds a threshold of a Schmitt inverter, the output of the Schmitt inverter is inverted. The time period from when the transistor is set in the high-impedance state to when the output of the Schmitt inverter is inverted is proportional to the photoelectric current. By measuring the time period, the photoelectric current value or luminance is detected.

Abstract: An optical flip-flop circuit which includes an electrical power source for providing an electrical signal, a light-receiving element provided in series with the power source for switching the electrical signal in response to an optical signal, a light-emitting element for emitting the optical signal in response to the electric signal, an electrical signal path between the light-receiving element and the light-emitting element, whereby the electrical signal passes from the power source to the light-emitting element in response to the optical signal received by the light-receiving element, a light path for directing the optical signal from the light-emitting element to the light-receiving element, wherein the light path and the electrical signal path form a signal loop through which a signal circulates, said circulating signal comprising the electrical signal through the electrical signal path portion of the signal loop and the optical signal through the light path portion of the signal loop, and input/output m

Abstract: An optical switch control circuit for controlling a microwave switch using single optical control link. The optical switch control circuit includes, a light source, a control connected to the light source, an optic fiber cable having an end coupled to the light source, a field effect transistor coupled to a second end of the optic fiber cable, an amplifier coupled to the field effect transistor, an analog to digital converter coupled to the amplifier, and a multi-bit microwave switch coupled to the analog to digital converter.

Abstract: An image processing apparatus comprises an image data generator and a characteristic converter for converting a characteristic of the image data generated by the image data generator. The characteristic converter includes a table for converting the image data in a first mode and a second table for converting in a second mode. The first and second tables are selectively used in recording one image. Data generator for generating data to be stored in the first and second conversion tables has a reference characteristic conversion table to be used as a base in generating the data.

Abstract: A digital representation of the time-integral of the illumination-dependent electric current flowing in a photo-conductive diode (1) is produced by feeding the current initially to the first capacitor (3a) of a series of capacitors (3a-3d). When the voltage across this first capacitor reaches a predetermined value the current is subsequently directed to the next capacitor (3b) of the series, and so on for the remaining capacitors (3c, 3d) sequence succession, by means of a voltage level responsive coupling cirucit (6). At the end of the integration period the voltage level in that capacitor which is only partly charged at that time is converted into digital form by means of a corresponding analog-to-digital converter (16) and applied to an output (18) together with a code identifying from which capacitor the digital output has been derived.

Abstract: A circuit for detecting the positions and intensities of peaks in a digital input signal (which may be a digitized version of a signal from a CCD forming part of a three dimensional imaging device) employs a second derivative of the input signal for validating the presence of each input peak. Each validation signal enables an interpolation circuit that determines the position of a peak by finding the location of a zero crossing point of a first derivative of the input signal. Each validation signal also enables a maximum detector for measuring the intensity of each peak. The arrangement does not require resetting after each detection of a peak and is less sensitive than prior devices to noise or DC or low frequency components.

Abstract: An electrical detector arrangement is provided having a chopper device for alternately exposing to and obscuring from a detector array a thermal radiation pattern to be detected and imaged. The outputs from the detectors of the array are multiplexed by a multiplexer and then digitized by means of a low cost analogue-to-digital converter. The digital output from the coverter during obscuration of the detector array from the thermal radiation pattern is stored in memory means and this stored data is converted to an analogue signal by a digital-to-analogue converter subtracted from the output of the multiplexer during exposure to and obscuration from the thermal pattern of the detector array by means of a differential amplifier. The output from the differential amplifier which substantially reduces the offset level of the multiplexed detector outputs is then fed to a further low cost analogue-to-digital converter.

Abstract: A digital optical receiver circuit adapted to operate over a wide input dynamic range without distorting its output signal. The circuit includes a first circuit for receiving input signals in a selected pulse width range and converting them into output signals of extended pulse width. A second circuit will then convert the output signals into digital signals of the same pulse width.

Abstract: Circuitry for digitizing received light into a digital pulsating signal, including a photodiode operable in response to light intensity for passing current to a capacitor for developing a voltage level thereacross. A voltage comparator with a hysteresis responds to the magnitude of the capacitor voltage level for tripping the comparator's output between a HIGH and LOW state which directs capacitor discharge to cycle the comparator output in a pulsating manner.In a preferred embodiment, the circuitry is powered by a flash storage capacitor along a pair of conductors which serve both to power the circuitry and to receive pulsating current levels indicating voltage comparator switching. The current levels are sensed and counted for producing a binary count output of received light energy. In another embodiment, the conductors also serve to carry a trigger signal for directing flash initiation.

Abstract: An electrical circuit assembly is provided for monitoring the flow of particulate fuel material in a chute having window areas on opposite sides thereof. The circuit assembly emits a light at one window end of the chute which is received at the opposite window end of the chute by a circuit assembly. The condition of the received light is dependent upon fuel material flow in the chute. If the flow is normal the emitted light will be intermittently interrupted by the particulate material resulting in chopped light being received by the circuit. If the chute is blocked downstream the chute will be filled with material and there will be no light received by the circuit. Similarly, if the blockage is upstream the chute will be empty and an uninterrupted light will be received. The circuit analyzes these received light conditions and produces output signals indicative of the mentioned fuel flow conditions.

Abstract: A digital transducer comprises a container having two disparate materials therein defining an interface, the interface being movable through the container responsive to a force, or forces, applied to one, or both, of the materials. A plurality of sensors are spaced along the container for sensing the interface, each of which is responsive to the presence of one of the materials. Means are included for suppressing the outputs of all of the sensing means responsive to the one material except that one sensing means which is responsive to the one material and nearest the interface.