Abstract: A device and method for quantitative determination of an analyte in a biological sample utilizes a non-transparent support medium for retaining a chromatogenic reaction product with the medium being exposed to a source of light for transmitting therethrough a scattered, uniform response light signal which is collected at a photosensitive device whereby the amount of the analyte is correlated to the intensity of the response light signal. The response light signal may be converted to a time-duration signal proportional to light intensity to facilitate the quantitative determination.

Abstract: A high-speed, high-resolution optical scanner system includes a flying spot scanner for scanning a beam across an object bearing information to be read and a high-bandwidth, high-sensitivity optical receiver including an avalanche photodiode for sensing the variation in light intensity of the beam reflected from the object being scanned; a power source for biasing the avalanche diode proximate its reverse breakdown voltage to produce high current gain in response to incident light; and a charge collector circuit responsive to the avalanche photodiode for producing a voltage proportional to the light incident on the avalanche photodiode.

Abstract: An improved electrophoresis and fluorescence detection apparatus has an electromagnetic radiation sensor juxtaposed with a sensing region. The output signal from the electromagnetic radiation sensor is a current signal, and the current signal is converted to a voltage signal. The voltage signal is summed with a programmable offset generated by an inexpensive eight-bit D/A converter. The offset signal is selected to establish a lower starting point for the dynamic range of the A/D conversion, and is selected to null some or all of the background electromagnetic radiation level. The summed signal is amplified and integrated in an integrator. The integrator is switchable under program control. The integrator is switched on for long and short intervals. The short intervals permit sensing over a dynamic range accommodating very high levels of fluorescence; very high peaks may be measured and features of the peaks distinguished.

Abstract: Circuitry for sensing a relatively large number of events, and outputting to processing circuitry only those events which have two characteristics: (1) a magnitude above a preselected threshold level, and (2) a rate of change greater than a preselected background rate of change. Logic circuitry is used to assign any event which has the desired characteristics to an available output channel. Subtracter circuitry causes the background to be subtracted from the sensing input, in order to limit the output to non-background events.

Abstract: A method for correction of influence of alternating voltage coupling in a signal chain of scanning opto-electronic sensors on radiometric data thereof is carried out by firstly ascertaining, and storing, characteristic times from the time constant of a RC-circuit of the signal chain of the respective spectral channel, a line scanning frequency and a number of image elements per scanline. A preliminary correction in the form of a recursive inverse RC-filtering of the sampling values is then performed for each image element of a channel with its characteristic time, and the preliminary corrected image data are intermediately stored channel-by-channel and line-by-line. In the case of the use of a dark reference source completely independent of external radiation, corrected pixel values are computed immediately and directly on the basis of the preliminarily corrected and intermediately stored image data with the aid of dark reference signals present at the sensor output for each channel.

Abstract: A ballistic optical camera trigger having an integrated circuit capable of onverting light to a proportional frequency, wherein the integrated circuit has a fast response time and a wide dynamic range which allows it to sense positive or negative changes in light fast enough to trigger without delay for high speed imaging without computational delays or jitter causing interference. The frequency output of the integrated circuit is tracked by a phase lock loop/voltage controlled oscillator to allow it to follow slow changes in light, but not fast changes in light caused by, for example, a projectile such as a bullet. The frequency output from the integrated circuit is provided to one input of a logic gate which receives at another input thereof, a shaped pulse from the phase lock loop/voltage controlled oscillator circuit, wherein the output of the logic gate is applied to a one-shot for outputting a trigger signal.

Abstract: An optical detection system includes an array of photodetectors, each of which is positioned for receiving light and converting the light into an electrical signal. A plurality of high pass filters is positioned with each one of the high pass filters electrically coupled to a respective photodetector for passing a portion of a respective electrical signal having frequency components at least as high as the high pass filter cutoff frequency. In one embodiment, each one of the filters comprises a capacitance coupled to the photodetector and a depletion mode FET with shorted gate-to-source terminals coupled between the photodetector and a bias voltage source.

Abstract: The apparatus has an optical reflecting sensor, an operational amplifier buffer with the electrical input connected to the output of the optical sensor, structure for averaging and delating a signal picked up at the output of the sensor, structure for the differential amplification of the signals on output respectively from the buffer and structure for comparing the signal outputting from the means with a known predetermined signal.

Abstract: A circuit measures the intensity of a monitored light beam by generating a signal which is of a specific time duration corresponding to light intensity. The circuit utilizes a photosensitive element for receiving the light and producing a variable control signal in direct correspondence to the light intensity. A capacitor network is placed in series with the photosensitive element, wherein the time duration for discharging the capacitor network is directly correlated to the intensity of the collected light.

Abstract: The present invention provides a resonance-type optical receiver circuit which keeps predetermined small distortion even when the received light level becomes high. The resonance-type optical receiver circuit varies the resistance value of variable resistance element 80, which is used as a load resistor to optical detector 4, in response to the intensity of output signal 10 of an amplifier. The load resistor varies in response to a variations of the received light level of the optical detector in this manner to keep the input to the amplifier lower than a fixed value.

Abstract: A laser based noncontact detection system is disclosed which is useful in automated manufacturing. The sensor system detects the presence or absence of an object that is either rotating or in some other continuous repetitive motion such as a rotating drill bit. This device is especially useful for detecting broken or absent drill bits used for drilling printed circuit boards. The system projects a laser beam onto the concave face of the flute near the tip of a drill bit and the amount of light which is reflected by the drill bit is sensed by a detector. The sensor is located at an angle oblique to the axis of rotation. Due to the rotation of the drill bit, fluctuating electronic signals are produced, detected and analyzed to determine the presence of the drill bit. The system automatically compensates for dust, debris and ambient light. Sensor positioning allows for greater drilling machine throughput since there is no need to fully retract the drill bit for breakage or damage detection.

Abstract: A power supply circuit for a liquid crystal welding lens or shutter develops a relatively low voltage AC signal for driving or powering the liquid crystal shutter to the clear state and two relatively higher or larger magnitude AC electrical signals for initially driving the shutter to the dark state and then for maintaining the shutter in the dark state; a variable frequency circuit for varying the frequency of the driving signal to the shutter to minimize power usage in the dark state and to avoid flicker in the clear state; and power saving and battery level indicator features are included.

Abstract: A sensor circuit for detecting light hazards or bright light sources that will cause discomfort. The sensor and sensor electronics which provide a wide sensitivity range which is fully automatically adjustable, and which has the ability to detect point sources of light. The sensor further has the ability to distinguish low power stable light generated from a small welding arc from bright ambient light or even direct sunlight.

Abstract: A laser warning device for sector-by-sector surveillance of the air space, comprises a plurality of module sections such that each surveyed sector is coupled through an optical antenna and an optical buffer to a module section.

Abstract: A method of and apparatus for differentiated measurement of smoke and/or vapor in the outgoing air of a device, especially a microwave unit for disinfection and sterilization of goods includes the steps of deriving a signal commensurate with the presence of vapor in accordance with the intensity increase of refracted and/or reflected light, and deriving a signal commensurate with the presence of smoke in accordance with the pulsed intensity decrease of light passing through the outgoing air.

Abstract: A monolithic integrated circuit using MOSFETs operatively configured in weak channel inversion made wherein pulses of light by interest are identified by identifying levels of light signal that exceed a threshold difference between a detected light level signal and a noise light level signal.

Abstract: A remote data transfer system, particularly an identification system for identifying objects such as livestock, pets and containers. An interrogator generates a directional light beam which the operator can direct at a selected animal or package up to 30-14 200 meters away; and a tag transponder carried by the object is activated only on receipt of the light beam, and transmits a coded RF signal. The signal is received by the interrogator which displays the identity of the animal derived from the coded RF signal. In its "receive" mode, the tag transponder requires minimal power, thereby prolonging battery life. A short rise time light pulse (or a pulse sequence) is identified and used to switch power to the transponder. After transmission of the coded RF signal, the transponder returns to a low power draw stand-by state. The tag is also able to transmit real time information, with or without the tag identity data.

Abstract: A lightning and strobe light detector and warning system capable of distinguishing strobe light and lightning flashes and indicating to an operator of the existence of a flash even under high illumination background conditions. The device may comprise a plurality of detectors and therefore not only distinguish between the strobe and lighting flashes but also indicate the direction of a flash.

Abstract: A lightwave receiver, suitable for CATV applications, includes an input photodiode that is capacitively coupled to the differential inputs of a balanced amplifier. Biasing of the photodiode may be achieved by connecting the photodiode in series between a pair of resistors, with the differential inputs being taken from either side of the photodiode. This arrangement avoids the use of a transformer, which exhibits considerable high frequency loss, thereby avoiding the bandwidth limitation inherent with a transformer.

Abstract: There is provided by this invention a photodetector and circuitry connected thereto wherein separate outputs are produced for low frequency and high frequency signals of the light impinging on the photodetector.

Abstract: A receiver for receiving an optical test signal from an optical transmitter pulsating at a selected repetition rate is disclosed. The receiver comprises an optical detector for sampling the test signal and generating a voltage signal pulsating at the repetition rate and with an amplitude proportional to the amplitude of the sampled test signal. The receiver also includes an indicator for indicating the amplitude of the test signal relative to the amplitude of a calibration signal.

Abstract: A light measuring circuit, consisting of an amplifying circuit amplifying the output of a photoelectric conversion element, is arranged to detect the occurrence of a low frequency component in the output of the photoelectric conversion element that comes to exceed a given level and, upon detection of that, to bypass the output of the photoelectric conversion element to prevent the output of the amplifying circuit from being saturated by a DC light (external or ambient light).

Abstract: A pixel placement sensing arrangement, useable in a spatial synchronization system, having a split photodetector, RC integrating circuits having time constants long relative to the exposure time of the photodetector connected to the respective halves of the split photodetector such that the current accumulated in the capacitors of the integrating circuits results in voltages proportional to the respective exposures of the halves of the photodetector, and a different amplifier which provides an output reflective of any difference in said voltages.

Abstract: An optical scanning system including an amplifier which automatically adjusts the background reference level. A photodetector, which is preferably a photocell, detects light reflected from or transmitted through objects such as code markings on forms and produces an output signal representative of the intensity of the detected light. This signal is coupled to the differential input of an amplifier through two circuits. One circuit rapidly couples the signal to one of the inputs and the second circuit couples an integral of the signal to the second input to automatically establish a background reference level. The amplifier may include means for adjusting the amplifier sensitivity and a small amount of positive feedback to increase the amplifier hysteresis so that once an object is detected, the amplifier output is unafffected by small changes in the input signal. This embodiment is useful in applications such as proximity detection.

Abstract: An improved photosensitive motion detector which detects abrupt changes within a field of view while ignoring gradual changes in ambient lighting therein. In addition, sensitivity to such changes is maintained without regard to the intensity level of the ambient light, and is not sensitive to the "flickering" of fluorescent lamps. Light from said field of view, which can contain an abrupt discontinuity therein, is focussed upon two substantially identical photocells, each of which is in parallel with one of two substantially identical photoresistors, each of which is closely optically coupled to one of two LEDs connected in parallel but in reverse polarity from a common junction to a common potential.

Abstract: The detector comprises an avalanche photodiode for receiving a light beam, a circuit for measuring the mean current across the avalanche photodiode and a bias voltage source. That source is controlled by the circuit for applying to the photodiode a bias voltage such that the mean current across the diode be substantially equal to an adjustable set value.

Abstract: Improved circuitry for detecting pulsed infrared light which is particularly suitable for use with laser therapeutic devices. Laser therapeutic devices generally utilize pulsed laser energy of infrared wavelengths. Because such light is invisible the operator of the therapeutic device cannot determine if it is actually working. The invention provides pulsed infrared light detection circuitry which is very compact so that it may be made part of the therapeutic device. The circuitry includes an infrared sensitive transducer coupled to the input of an inverting operational amplifier, a peak detector coupled to the output of the inverting amplifier, and a non-inverting amplifier coupled to the output of the peak detector for driving a display to indicate the detection of pulsed infrared energy.

Abstract: A light detector circuit is described in which the baseline level of the output signal of a light detector is stabilized by feeding back a control signal to an element that has a voltage variable resistance and is connected in series with the light detector across a voltage source. Several embodiments are shown. In one embodiment a differential amplifier circuit with an integrating feedback circuit is employed to establish a stabilized control voltage.

Abstract: An illumination flicker measuring device having a photodiode detector producing a signal proportional to the illumination being measured. An input amplifier for increasing the level of the signal produced by the photodiode detector. A capacitor is inserted so as remove the average light output component of the signal produced by the photodiode detector and which is then entered into a rectifier and amplifier so as to remove the lower envelope of the signal and amplify the upper envelope of the signal. A low pass filter is then attached to the rectifier and amplifier so as to remove the 120 Hz ripple produced by the 60 Hz system powering the illumination system. The output of the low pass filter is then passed through a capacitor to remove DC components present and then rectified and amplified again to produce a signal which is proportional to the amplitude of the flicker present in the illumination system.

Abstract: A leader tape detecting circuit which accurately detects the presence of a leader of a cassette tape independently of the type of tape or its condition. A light receiving element such as a phototransistor is disposed to detect the quantity of light passing through or reflected by the cassette tape. The output of the light receiving element is coupled directly to one input terminal of a comparator and through an integrator circuit to the other input terminal of the comparator. When the tape confronting the light receiving element changes from magnetizable tape to the leader, the quantity of light detected by the light receiving element changes and the output of the integrator circuit becomes different than that of the light receiving element. The detector produces an output signal representing this difference which is differentiated to produce the final output.

Abstract: A controller provides a high voltage to maintain an electro-optic shutter in a transparent condition until a flash of light which would be harmful to personnel is sensed by a phototransistor. The controller then shorts the shutter to ground to minimize light transmission to the user and maintains light transmission at the pre-flash level for a predetermined time to allow the flash to subside. A log converter and differential trigger circuit keep the controller from being triggered by other light flashes which are not dangerous.

Abstract: A detector for detecting radiation from a Q-switched laser. The detector prises a plurality of silicon photo-diodes (10) which develop an output signal when struck by incident radiation from the Q-switched laser. The output of the photo-diodes is connected to a pulse-width discriminator (12) and a pulse-amplitude discriminator (13). The pulse-width discriminator generates an output signal only if the amplitude of the output pulse from the photo-diodes is less than 300 nanoseconds, signifying an input pulse from a Q-switched laser. The pulse-amplitude discriminator develops an output signal only when the photo-diode is saturated, again, indicating radiation from a Q-switched laser. The presence of a signal from either the pulse-width discriminator or the pulse-amplitude discriminator indicates that the incident radiation on the photo-diode was indeed from a Q-switched laser.

Abstract: Detection circuit for objects has a light source located to illuminate a plurality of light sensitive electrical elements. The light sensitive elements are of the type to alter their electrical characteristics when illuminated and are connected in series in an electrical circuit. Means are provided for detecting the rate of change of one of the current flow through or the voltage across the series circuit and for producing an output varying as said rate of change.

Abstract: An indicating device is disclosed for showing the level of a fluid in a container. A transparent rod having a sensing end is immersed in the fluid when the container is filled above a predetermined level. The sensing end is shaped to cause a substantially total reflection of a beam of light projected in the rod from an opposite end of the rod when the sensing end is not in contact with the flowable substance. A light source and photoelectric detector are arranged at the opposite end of the rod and a circuit is connected to the photoelectric detector for detecting when a predetermined amount of reflection occurs and also for preventing response of the device to slopping of the fluid to and fro in the container.

Abstract: An infrared detector of sufficient sensitivity and stability to provide for the reliable detection of a glowing ember moving through an enclosed carrier system (duct or conveyor) in which a photo-resistive device for viewing the interior of the carrier is connected into suitable circuitry that does not respond to slowly changing ambient light, but which produces a voltage pulse in response to a moving glowing ember passing through the field of view of the detector; said voltage pulse being utilized to provide an output signal which may actuate an alarm or release extinguishant.

Abstract: Apparatus for indicating the concentration of a particular constituent in a fluid including a sensing device for sensing the concentration of a particular constituent in a fluid and for providing a response; and an electronic device including a differentiating circuit for differentiating an electrical input signal which is proportional to the sensing response for providing a substantially constant output signal which is a measure of the sensing response differentiated with respect to time, which output signal is an indication of the concentration of the constituent in the fluid. The sensing device is operated during a sampling period in which the reaction of such constituent to the sensing device is linear.

Abstract: A detector for marks having a color which contrasts with the mark background employs a solid state light source projecting a light beam having a plurality of wave length components corresponding to a plurality of colored light wave lengths. The light beam may approach the appearance of white light. A pulse modulated detector or sensor is used for receiving light reflected from colored surfaces having contrasting colored marks thereon, wherein high ambient light level rejection is obtained and high signal to noise ratio is provided in a sensor output. The sensor output is gated to eliminate between pulse noise, and the gated output is integrated to obtain a reference signal to which the gated pulse is continuously compared. An increase or decrease in signal is used to provide a light or dark mark indication respectively as a result of the comparison. Feedback from the output suppresses signal instability which may exist at the edges of the detection threshold.

Abstract: A flame monitoring system includes a flame sensor for producing a flame signal as a function of flame conditions in a monitored environment and flame signal enhancing circuitry coupled to the flame sensor. The flame signal enhancing circuitry has a first response as a function of a first characteristic of the flame signal and a second response different from the first response as a function of a second characteristic of the flame signal and is arranged to combine the first and second responses to provide an enhanced flame signal representative of the monitored flame.

Abstract: A photometric monitoring device for detection and surveillance of objects entering and leaving a light field is provided wherein a monitored light source is compared with a reference light source in such a manner that abrupt or rapid changes in monitored light are detected and gradual changes are ignored. A first photo cell for monitoring a light source is coupled to the input of an operational amplifier having a feedback loop which includes a reference light source coupled to a second photocell. An RC network delays the reaction of the operational amplifier in balancing the voltage across both of said first and second photocells when abrupt changes occur, allowing a signal to be developed. Additional circuitry includes a comparator responsive to such developed signals which exceed predetermined limits, producing an output signal for use by a utilization device, such as a camera, recording device, alarm system, or the like.

Abstract: An electro-optical scanner for detecting variations in a web and generating output signals representative of the variations is provided with discriminator logic and alarm circuitry that indicates when the output signals shift from a value exceeding a predetermined positive (negative) threshold value to a value beyond a predetermined negative (positive) threshold value within a prescribed minimum period of time as an occurrence of an abrupt change in web density and processing circuitry for determining and indicating when the number of such occurrences per unit time exceeds a threshold or predetermined number.