Abstract: Mid-procedure termination of a mononuclear cell collection procedure may prevent collection of an amount of red blood cells that is required to harvest a complete mononuclear cell product. Blood separation systems and methods are provided for minimizing the impact of or recovering from mid-procedure termination of such a mononuclear cell collection procedure. According to one approach, blood or separated red blood cells are conveyed into a red blood cell collection container relatively early in the procedure to minimize the impact of a later termination of the procedure. According to another approach, blood and/or separated red blood cells within a fluid processing assembly are redirected through the fluid processing assembly following mid-procedure termination to allow for at least partial mononuclear cell collection.

Abstract: The invention relates to a method for detecting particles, having the steps of: receiving (S1) a measurement signal; calculating (S2) at least one estimated noise value using the received measurement signal; and detecting (S3) the particles using the measurement signal on the basis of at least one detection criterion, wherein the at least one detection criterion depends on the at least one calculated estimated noise value.

Abstract: A visibility meter, a street light device and an operation method thereof are provided. The visibility measurement method includes: transmitting a visible laser through an optical transmitter; receiving the visible laser through an optical sensor to generate a sensed result; and calculating a visibility according to the sensed result.

Abstract: Embodiments of the disclosure provide a method for evaluating dialyzers used in different medical applications (e.g., hemodialysis). Red blood cell volume lost in a dialyzer is monitored by obtaining blood flowrate measurements and hematocrit measurements at input ports and output ports of the dialyzer. The flowrate and hematocrit measurements are used to determine an accumulation of red cell blood volume in the dialyzer. The measurements may be obtained in a lab environment with an in-vitro blood source or may be obtained in a clinical setting with an in-vivo blood source from a patient.

Abstract: A device for applying a product to be dispensed on a skin of a user by iontophoresis, includes: at least one storage container for storing the product to be dispensed; at least one dispensing cavity able to receive the product to be dispensed; at least one first iontophoresis electrode; an electronic control circuit; and a measuring system for measuring a physical or physico-chemical parameter, the measuring system being connected to the electronic control circuit and configured to send a signal indicative of a parameter measurement. The first iontophoresis electrode and the measuring system are installed in the dispensing cavity, the electronic control circuit being configured to compare the value of the physical or physico-chemical parameter measured in the cavity to a reference threshold value so as to detect if the product is absent from the cavity.

Abstract: The invention relates to a method for determining properties of particles in a medium by measuring scattering of a light ray guided through the medium. The light ray (2) can be led through a scattering zone (4) more than once. Both the scattered (5) and unscattered light are measured using the same sensor (6). The invention also relates to a measuring device for measuring the properties of particles in a medium, such as flue gas.

Abstract: The present disclosure describes embodiments of a patient monitoring system and methods that include the measure and display of hemoglobin statistics. In an embodiment, total hemoglobin trending is displayed over a period of time. Statistics can include frequency domain analysis, which may be unique for each patient monitored. The total hemoglobin trending and/or statistics can further be used to help control the treatment of a patient, such as being used to control IV administration.

Abstract: A sensor device for optically detecting characteristics of a fluid. The device includes a housing with a base portion from which first and second appendages extend at least partially facing one another, and between which in use a fluid is present, and first and second optoelectronic devices adapted to transmit and receive radiation, respectively, mounted at the first and second appendages of the housing, respectively. The arrangement is such that in use a radiation beam transmitted by the first optoelectronic device propagates in an optical path which includes a portion crossing the fluid between said appendages and reaches the second optoelectronic device. This optical path includes at least one reflecting surface made integrally in an appendage of the housing and adapted to deflect the radiation beam between the associated optoelectronic device and the fluid crossing portion.

Abstract: A system of measuring hemoglobin and bilirubin parameters in a whole blood sample using optical absorbance. The system includes an optical-sample module, a spectrometer module, an optical fiber module optically connecting the optical-sample module to the spectrometer module, and a processor module. The optical-sample module has a light-emitting module having a LED light source, a cuvette and a calibrating-light module. The processor module receives and processes an electrical signal from the spectrometer module and transforms the electrical signal into an output signal useable for displaying and reporting hemoglobin parameter values and/or total bilirubin parameter values for the whole blood sample.

Abstract: A smoke detector having a light source for generating a beam of light is disclosed. The smoke detector is arranged to transmit the beam along an optical axis and includes a sensor for receiving light scattered from the beam off the optical axis by smoke; and a light trap comprising one or more walls that define a volume for receiving light that passes unscattered from the light source past the sensor along the optical axis. The volume includes a first end closest on the optical axis to the light source; and a second end furthest on the optical axis from the light source. The volume is open at said first end but is otherwise closed, and at least one of the walls is sloped from the first end to the second end, such that the light trap progressively narrows from the first end axially towards the second end.

Abstract: The present disclosure describes embodiments of a patient monitoring system and methods that include the measure and display of hemoglobin statistics. In an embodiment, total hemoglobin trending is displayed over a period of time. Statistics can include frequency domain analysis, which may be unique for each patient monitored. The total hemoglobin trending and/or statistics can further be used to help control the treatment of a patient, such as being used to control IV administration.

Abstract: This disclosure relates generally to analytical instruments for measuring one or more properties of specimens or samples to be analyzed and, more particularly, to an analytical instrument with an adjustable optical path length. An analytical instrument may include a specimen support upon which a specimen may rest and a compression plate for controllably adjusting an optical path length of the specimen between the specimen support and the compression plate. In particular, a specimen may contact both the specimen support and the compression plate such that controlling a distance of the compression plate with respect to the specimen support effectively controls the optical path length of the specimen. An analytical instrument may include collimating lenses to collimate electromagnetic energy for transmission through a specimen and converging lenses for directing electromagnetic energy transmitted through the specimen into one or more sensors.

Abstract: Disclosed is a use of reaction kinetics to generate multiple dose-response curves from a single reaction, thus eliminating the need to run a second experiment with additional sample, reagents, and time to cover a broader measuring range than is available in a standard assay. Using a single protocol, the differences in the reaction kinetics for different sample concentrations yield different responses at different measurement times. Selection of the appropriate dose-response curve cross-section increases the measuring range and accuracy of the assay from a single reaction without substantially increasing imprecision. Several overlapping dose-response curves are pieced together to provide a standard curve to ensure continuity throughout the expanded measuring range.

Abstract: The present disclosure describes embodiments of a patient monitoring system and methods that include the measure and display of hemoglobin statistics. In an embodiment, total hemoglobin trending is displayed over a period of time. Statistics can include frequency domain analysis, which may be unique for each patient monitored. The total hemoglobin trending and/or statistics can further be used to help control the treatment of a patient, such as being used to control IV administration.

Abstract: A particle detection system including; at least one light source adapted to illuminate a volume being monitored at at least two wavelengths; a receiver having a field of view and being adapted to receive light from at least one light source after said light has traversed the volume being monitored and being adapted to generate signals indicative of the intensity of light received at regions within the field of view of the receiver; a processor associated with the receiver adapted to process the signals generated by the receiver to correlate light received at at least two wavelengths in corresponding regions within the field of view of the receiver and generate an output indicative of the relative level of light received at the two wavelengths.

Abstract: A beam detector including a light source, a receiver, and a target, acting in cooperation to detect particles in a monitored area. The target reflects incident light, resulting in reflected light being returned to receiver. The receiver is capable of recording and reporting light intensity at a plurality of points across its field of view. In the preferred form the detector emits a first light beam in a first wavelength band; a second light beam in a second wavelength band; and a third light beam in a third wavelength band, wherein the first and second wavelengths bands are substantially equal and are different to the third wavelength band.

Abstract: A gas detection system with an inner ring cavity fiber laser using saturated absorption optical fiber is provided. The system comprising a ring fiber laser consisted of a pump source, a wavelength division multiplexer, a first active optical fiber, a first coupler, a fiber Bragg grating and a second coupler connected successively; an optical isolator coupled between said first active optical fiber and said first coupler; a second active grating connected between said fiber Bragg grating and said first coupler; a detection gas chamber connected between said first coupler and said second coupler; a first photoelectric detector for detecting the laser intensity outputted from said ring fiber laser to generate a first light intensity signal; a second photoelectric detector for receiving the intensity measuring beam passing through the detection gas chamber to generate a second light intensity signal; and a feedback control unit.

Abstract: A method and apparatus are provided for automatically detecting the type of replacement fluid loaded by the operator during a therapeutic exchange procedure and to provide a warning alarm if an incorrect fluid is used. After the operator connects the container of replacement fluid to the replacement fluid line of a single-use kit and enters into the controller an identification of the exchange procedure to be performed, the replacement fluid is flowed through a segment of the kit in proximity to a sensor associated with the hardware component that detects the type of fluid flowing through the segment. The controller verifies whether the replacement fluid detected in the segment corresponds to that appropriate for the selected exchange procedure, and notifies the operator in the event that an incorrect replacement fluid has been loaded.

Abstract: A gas detection system with an inner ring cavity fiber laser using saturated absorption optical fiber is provided. The system comprising a ring fiber laser consisted of a pump source, a wavelength division multiplexer, a first active optical fiber, a first coupler, a fiber Bragg grating and a second coupler connected successively; an optical isolator coupled between said first active optical fiber and said first coupler; a second active grating connected between said fiber Bragg grating and said first coupler; a detection gas chamber connected between said first coupler and said second coupler; a first photoelectric detector for detecting the laser intensity outputted from said ring fiber laser to generate a first light intensity signal; a second photoelectric detector for receiving the intensity measuring beam passing through the detection gas chamber to generate a second light intensity signal; and a feedback control unit.

Abstract: The present invention provides electrokinetic microfluidic cytometers useful for detecting and/or sorting fluid-borne particles. In some embodiments, the electrokinetic microfluidic flow cytometer apparatus comprises a substrate having a microchannel formed therein, a particle-sensing gate that reduces the cross-sectional area of a portion of the microchannel, a pair of signal- and noise-detection electrodes, and a particle-detection circuit that is electrically connected to the signal- and noise-detection electrodes and is configured to generate a particle-detection signal responsive to differences in resistivity across the particle-sensing gate.

Abstract: One embodiment relates to an apparatus comprising a light source adapted to transmit light through a liquid, and a detector adapted to detect an intensity of the light after it passes through the liquid. The apparatus may also include a device to process data relating to the intensity of the infrared light and compare the processed data to predetermined control data. The apparatus may also include a controller adapted to transmit a signal to a liquid dispenser if the processed data differs from the control data by a predetermined amount. The light may be selected from the group consisting of ultraviolet, visible, infrared, and microwave light. Other embodiments are described and claimed.

Abstract: Methods, storage mediums, and systems for correlating pulses generated from multiple interrogation regions in a flow cytometer to particular particles flowing through the flow cytometer are provided. Embodiments of the methods, storage mediums, and systems include configurations for calibrating a flow cytometer using a calibration particle having a unique signature to determine a time-of-flight for particles flowing through the flow cytometer. Based on the calculated time-of-flight and relative positions of interrogation regions corresponding to collectors of the flow cytometer, the methods, storage mediums, and systems may further include configurations for associating other signal pulses to particles of one or more different particle sets.

Abstract: A sensing device able to do concurrent real time detection of different kinds of chemical, biomolecule agents, or biological cells and their respective concentrations using optical principles. The sensing system can be produced at a low cost (below$1.00) and in a small size (˜1 cm3). The novel sensing system may be of great value to many industries, for example, medical, forensics, and military. The fundamental principles of this novel invention may be implemented in many variations and combinations of techniques.

Abstract: A method of processing time-discrete measured values, which can be described in their time characteristic by a first exponential function which has a first time constant, the method comprising the steps of: detecting a first measured value and storing the first measured value, detecting a second measured value and storing the second measured value according to a defined time interval with respect to the detection of the first measured value, filtering the first measured value and second measured value by calculating a sum of the first measured value and a weighted difference between the second measured value and the first measured value, thereby generating time-discrete output values which can be described in their time characteristic by a second exponential function having a second time constant different from the first time constant, and outputting the output values is disclosed.

Abstract: A gas sensor configuration comprises a radiation-emitting radiation device, a gas measuring chamber, a detector unit and an evaluation device. A measuring gas that contains at least one gas component is present in the gas measuring chamber. The evaluation device detects the gas component and/or its concentration depending on the output signal of the detector unit. The radiation emitting device comprises at least one source that emits a measuring radiation and at least one reference radiation source, the latter being switched on periodically to measure the aging state of the source that emits the measuring radiation. The evaluation device detects the aging of the source that emits the measuring radiation on the basis of deviations with respect to the output signals of the detector unit when the reference radiation source and the source that emits the measuring radiation are switched on, and, if necessary, compensates for the aging.

Abstract: Algorithm for filter selection of binary filters configured to solve the problem in question with the aim of determining smallest concentration changes in substance mixtures wherein one or a plurality of low-concentration lead components can be reliably detected in the presence of higher-concentration matrix or background components using the selected broad-band binary filters. The spectral power transmitted or reflected by the substance mixture is detected by a plurality of photosensitive detectors which are spectrally broad-banded and provided with binary filters, the detector signals being used for exact determination of the substance concentrations.

Abstract: An apparatus including a sample holder which fixedly holds sample vessels arranged on a same arc, a partition plate, a light guide which is configured by optical fibers and which transmits fluorescent signals emitted from respective test samples, to an optical sensor, the single optical sensor, and a light source which generates excitation light. Fluorescent signal emission ends of the light guide are opposed to the optical sensor, and fluorescent signal incidence ends of the light guide are respectively opposed to the sample vessels via the partition plate therebetween. The partition plate includes an excitation light optical unit for selectively guiding the excitation light from the light source to only one of the sample vessels arranged on the arc, and a fluorescence optical unit for guiding only the fluorescent signal emitted from a selected one of the sample vessels to the light guide.

Abstract: The invention provides a method consisting successively in producing two electromagnetic radiations of the same wavelength that is modulated as a function of time over a range of wavelengths, a "measurement" one of said radiations passing through a gas that presents selective absorption for said radiation in the range, while the other radiation constitutes a "reference" radiation. Each of said radiations is transformed into a respective "measurement" or "reference" electrical signal. The measurement signal is divided by the reference signal to obtain a first quotient electrical signal which is in turn split into two portions: a time-varying AC portion and a DC portion that does not vary with time. The AC portion is divided by said DC portion in order to obtain a second quotient electrical signal representative solely of the electromagnetic radiation absorbed by the gas.

Abstract: In an automatic analyzer such as blood analyzer, it is important to observe whether the sample, such as a blood sample, is sucked correctly or not. In an apparatus for observing suction of a sample, comprising a sample suction tube, a luminous element for emitting light toward the sample suction tube being driven by a driving circuit, a photo sensor for receiving the light from the sample suction tube, and a judging circuit for judging the sample suction on the basis of the signal from the photo sensor, a controller is provided in order to drive the luminous element so that the output (Vp) of the photo sensor may be nearly the reference value (Vr) before a sample suction, and to drive the luminous element so as to hold the driving state during the sample suction. Thus, the sensitivity adjustment of the apparatus for observing suction of a sample may be automated, and the observing capability of the apparatus is enhanced.

Abstract: A particle detector that determines the presence of particles in an enclosed volume includes a laser that directs an optical beam to a beam splitter that produces first and second beams. An optical system directs the first beam into the enclosed volume. A detector is positioned adjacent the volume in order to receive back scattered optical energy arising from a particle in the volume encountering the first beam. The back scattered optical energy and the second beam are optically combined so as to overlap in a region and in the overlap region the back scattered optical energy and second beam are in the same state of focus, of the same polarization and are substantially parallel. A detector located at the overlap region produces an electrical signal indicative of the intensity of the back scattered light. A signal processor analyzes the electrical signal to determine the presence of the particle.

Abstract: The probe (20) includes a conductivity sensor (38) and an optical sensor (39) for detecting the depth of a layer of oil, gasoline, etc floating on the surface of water in a well. A battery (60) is included in the probe, and a resistor (R1) is provided in series with the conductivity sensor. When the probe is in oil, both sensors are OFF, and no voltage is detectable at the surface; when the probe is in air, the optical sensor is ON and the conductivity sensor is OFF, so that a maximum voltage is detectable at the surface; and when the probe is in water, the optical sensor is OFF and the conductivity sensor (with its resistor) is ON, so that an intermediate voltage, as set by the value of the resistor, is detectable at the surface.

Abstract: The Rolling Average Rate Read Indicator and Method detects the presence of a particular constituent in either a solid, liquid or gas and returns a rapid and accurate measurement of the concentration of the constituent. The Indicator is comprised of a sensor (12) containing a stepper motor (36) driven tape impregnated with a chemical substance reactive to a particular constituent. Discoloration of the tape occurs in the presence of the constituent and this discoloration is converted to an electrical signal which is indicative of the rate of change in the chemical reaction taking place and is linear for some portion of time. The signal is differentiated (16) and the resultant differentiated signal is indicative of the arithmetic mean of a plurality of instantaneous values taken at intervals during the linear portion of the reaction. The extent of the reaction as evidenced by the level of the sensor output signal is continuously monitored and compared (26) to a known value.

Abstract: An air conditioning system having a circuit for determining whether sufficient refrigerant is present in the system by detecting a phase state of the refrigerant. The circuit comprises a comparison circuit for comparing a detection signal of a state detecting sensor with a first reference value and a second reference value lower than the first reference value. An indication signal is output after the detection signal exceeds the first reference value until the detection signal is less than the second reference value. When the amount of refrigerant in the system is proper, even if the detection signal varies due to translucent lubricating oil in the refrigerant, the indication signal is continued to be output unless the detection signal drops below the second reference value. The amount of refrigerant in the refrigerant circuit can be accurately determined and maintained within a proper range.

Abstract: Analyzing the level of a treating agent and/or stress metals in a body of water containing an inert transition metal tracer added to the water proportionally with the treating agent by determining the absorbance (first absorbance value) of a reagent dye added to water, said dye producing a second absorbance value when reacted at the same concentration with the tracer and stress metals in a measure of said body of water, and said dye producing a third absorbance value when reacted at the same concentration with only the transition metal contained in a measure of said body of water; determining the second and third absorbance values and resolving their differences to determine the concentration of the tracer and, separately, the concentration of said stress metals.

Abstract: An apparatus and method for making a photometric determination regarding the contents of a sample, such as the absorbance characteristic of a blood serum sample. The improvement allows measurements to be taken after a reduced warm-up period and compensates for variations in the lamp intensity during the period over which measurements are taken. A feedback circuit is provided between a reference photodetector and the light source for causing the light source intensity to asymptotically approach a final stable value in a smooth exponential curve. Signal processing means processes outputs of the reference and sample photodetectors taken at different times so as to compensate for variations in the source intensity over the time period during which the outputs are taken. Still further, the photometer allows resonant frequency mixing of the contents of a cuvette while disposed in the photometer by causing the entire optical assembly, in which the cuvette is mounted, to vibrate at its resonant frequency.

Abstract: An indicator circuit is provided for an apparatus that measures the concentration of a selected component in a test sample. The apparatus generates a test voltage that represents the concentration of the component in the test sample. The circuit generates a series of range voltages, each of which represents a respective one of a series of potential concentration ranges of the component in the test sample. A switching circuit selects an adjacent pair of range voltages immediately above and below the test voltage and applies the selected range voltages across an incremental voltage divider such that the voltage difference of the selected range voltages is divided into a series of incremental voltages, each of which represents a respective one of a series of potential incremental concentration levels of the component within each concentration range.

Abstract: A photometric analyzer for measuring differential total reduced sulfur in a sample gas stream is provided. It includes a supply for a sulfur bearing gas sample, an oven having an inlet connected to the supply for converting TRS to SO.sub.2 and an outlet through which the gas sample is discharged. A valve is connected to the outlet of the oven. An SO.sub.2 bypass line is connected between the supply and the valve. A sample cell with transparent ends has an inlet adjacent one end connected to the valve for alternately receiving sample gas from either the oven or the bypass line and has an outlet adjacent the other end. A pump connected to the sample cell outlet draws the gas sample through the sample cell. A light source at the one end of the sample cell directs light of a predetermined wave length through the sample cell. A light sensing device at the other end detects the amount of light passing through the sample cell at any given time and provides an output signal to an analyzer.

Abstract: The present invention comprises a simple multi-purpose on-line system for monitoring the concentration and/or the total amount of an organic analyte species or inorganic analyte species in an aqueous solution. The on-line detection system comprises a detection column and a sensor mounted around the detection column. The sensor consists of an electromagnetic radiation source (typically a light source) and an appropriate detector for the electromagnetic radiation. The response from the detector drives an electric circuit, which provides a signal to a recorder as well as a means to trip an alarm system and/or a process system.

Abstract: The present invention relates to an improved dual beam multichannel spectrophotomer employing a simple and novel optical system in combination with photodiode arrays and a unique logrithmic data converter to convert light signals to absorbance. In particular, the optical system utilizes optical elements in a novel arrangement to direct a pair of equivalent sample and reference beams in an essentially parallel formation respectively through a sample and reference cell and to focus and direct the emergent sample and reference beams to a single flat horizontally ruled grating which disperses each of the sample and reference beams respectively onto a pair of vertically disposed photodiode arrays whereby the light signals are converted into absorbance units (AU) by an unique logarithmic data converter. The spectrophotometer is highly accurate, has very low drift, less than 2.times.10.sup.-4 AU/.degree.C., and very low noise, less than .+-.2.times.10.sup.-5 AU.

Abstract: A system for transmission loss comparison permits enhanced accuracy over a wider dynamic range by providing a reference channel including a transmitter, receiver, and transmission path therebetween, and a sample channel, including a transmitter, receiver, and transmission path therebetween. A feedback arrangement is provided for adjusting the outputs of both of the reference and sample transmitters in relation to the signal output of the reference receiver, so as to produce a desired signal level of the reference receiver's output over a given dynamic range, so as to compensate for loss over the reference transmission path. In this way, a comparator connected to the outputs of the two receivers receives inputs that are compensated for effects of losses over the reference transmission path.

Abstract: A separation type light blocking smoke detector detects smoke present between a light emitting section and a light receiving section spaced therefrom by detecting blocking of light between the light emitting section and the light receiving section. The detector includes a light emitting section driving circuit, a counting circuit, and a storage circuit. The light emitting section driving circuit changes the emission intensity of the light emitting section in accordance with a predetermined changing mode for every repetitive cycle. The counting circuit includes a first comparator and an updating signal generator, and counts a physical amount corresponding to a period during which an output from the light emitting section falls in a predetermined range for each repetitive changing cycle. The storage circuit includes a second comparator and an AND gate, and stores a count value of the counting circuit in an arbitrary repetitive cycle.

Abstract: A system for measuring the density of certain ions or neutrals within a plasma without probe intervention. When cylindrical symmetry is present, the system also provides measurement of spatial distribution of excited ionic states within the plasma. The system allows spatial distribution of contaminant ions in magnetic confinement thermonuclear fusion devices to be monitored. These functions are accomplished by directing two laser beams through a region containing a plasma. The laser means are at respective wavelengths chosen to be in and closely adjacent to a spectral region near the electronic transition frequency of the ionic species of interest in the plasma. The intensities of the two wavelengths are then measured and compared to obtain the desired data and characterization.

Abstract: A smoke detector comprising a light emitting section from which pulse light is radiated to a detection area with a predetermined period and a light receiving section which is disposed so as to be opposite to the light emitting section to receive the light for detecting a change caused in the detection area in the form of a change in photo-output level. The light receiving section has a monitor terminal for outputting a monitor signal corresponding to the photo-output level. When a measuring apparatus is externally connected to the monitor terminal, the supervision period is shortened as compared with the normal supervision period, so as to enable the monitor signal to be supervised substantially in real time, thereby facilitating an adjusting operation.

Abstract: An environmental abnormality detecting apparatus for detecting abnormality in atmosphere such as heat, smoke, and a gas. A sampling circuit is provided for periodically sampling analog signals from a detector for detecting these phenomena. A quantizer quantizes sampled signals with step levels. An accumulator having a plurality of counters provides different accumulation times corresponding to the step levels. Reliability in accumulation effect is not degraded, and an abnormality signal can be detected in a short period of time when a degree of abnormality is high.

Abstract: This invention relates to an optical absorptiometer which is characterized by a light source unit of a broad wavelength having a source of constant energy which is collimated into two light beams, one of which is transmitted through the liquid to be measured, and another beam which is transmitted through a conductor and acts as a reference beam, and a detector unit which contains two photocells, one photocell for measuring the beam transmitted through the liquid to be measured, and another photocell which measures the reference beam, a position in the absorptiometer for optically placing the liquid to be measured between the source unit and the detector unit, and means for measuring the energy difference between the light beams of the measured liquid and the reference beams in terms of absorbance, and means for converting this result to an electrical signal.

Abstract: The percentage gas concentration within a sample as measured in a conventional optical bench is derived from the composite signal of the reference beam and sample beam transmitted through a sample cell in the optical bench. The primary source, which generates the reference beam and the secondary source which generates the sample beam are driven ninety degrees out of phase. The composite signal derived from the detector in the optical bench is digitized and then integrated according to the quadrature of the primary component of the composite signal derived from the reference beam, and is also integrated according to the quadrature of the secondary component of the composite signal derived from the sample beam. What is obtained is the integral of the absolute value of the secondary component and the integral of the absolute value of the primary component of the composite signal over one cycle of the reference beam and sample beam.

Abstract: An improved toner control system having a pair of matched photosensitive devices connected in series and receiving equal amounts of light, wherein one device responds to light transmitted through the toner-containing developer and the other device responds to light transmitted through an adjustable aperture or attenuator.

Abstract: In a line extinction detector using a pulse-operated radiation source, a radiation receiver is connected to an input amplifier of an evaluation circuit. The output pulses generated by the input amplifier are compared to a reference voltage. Circuit elements having a time constant above one minute are provided to adjust either one of the voltage of the output pulses or the reference voltage such that their difference practically becomes zero. The output pulses of the input amplifier are further compared to an alarm threshold derived from the reference voltage and an alarm is triggered when the output signal falls below the alarm threshold value. The output pulses of the input amplifier are also compared to a disturbance threshold value and a disturbance signal is generated when the output signal drops below the disturbance threshold value.

Abstract: A smoke detector is disclosed having a radiation source operated in a pulsed mode. Externally of a direct radiation region of the radiation source there is arranged a radiation receiver which, in the presence of smoke or other particles emanating from a combustion process and located in the radiation region, is impinged by scattered radiation and delivers an output signal to an evaluation circuit. The evaluation circuit contains switching elements which, when the number of source output signals or pulses exceeds a predetermined threshold value for the number of source output pulses, delivers an alarm signal. Near to the radiation receiver there is arranged a reference cell in the direct radiation beam of the radiation source, this reference cell controlling the emission of radiation by the radiation source.

Abstract: A smoke detector contains two radiation transmitters and two radiation receivers. Each of the radiation transmitters emits in a different spectral region, for instance, one emits above and the other one below 600 nm. One part of the radiation of both radiation transmitters is conducted via a measuring path, which is accessible to smoke, to one of the receivers constituting a measuring radiation receiver, and another part of such radiation is conducted via a comparison path, which is not accessible to smoke, to the other of the receivers constituting a comparison radiation receiver.