Abstract: In an ink concentration measuring circuit, a light emitting diode emits light toward an ink cell. A first photo diode receives reflected light from the ink cell and provides a reference signal and a second photo diode receives direct light through the ink cell and provides an ink signal. A ratio of the reference signal to the ink signal is then calculated and used to determine a concentration of ink in the ink cell. Since changes in the ink temperature affect the ink concentration, the ink temperature may be measured and the result used to modify the ratio, compensating for the changes in ink temperature. Also, ink pressure may be measured and used to modify the ratio, compensating for changes in the dimensions of the ink cell.

Abstract: Apparatus for measuring the level of an item in a liquid including first and second light transmitting cylinders, a first piston and an associated conduit for conducting liquid to the first cylinder, a second piston and an associated conduit for conducting liquid to the second cylinder, a third piston and an associated conduit for conducting indicator solution to the second cylinder, a light source for transmitting light through the first and second cylinders, and a detector for measuring the difference in light transmissibility of the liquids in the first and second cylinders and providing an output depending thereon. A method of testing the level of an item in a liquid including the steps of providing a first sample of the liquid containing the item, providing a second sample of the liquid with a measured amount of indicator solution therein, comparing the light transmissibility of the first and second samples, and providing an output which is a measurement of the level of the item in the liquid.

Abstract: A spectro photometer deflects a measuring beam off its original axis to pass through a long sample, and returns the measuring beam to its final direction after passing through the sample. The sample is guided along a path which is clear of a reference beam of the spectro photometer. This arrangement permits double-beam measurement of long samples, with good signal-to-noise ratio. Deflection is accomplished using a plurality of mirrors.

Abstract: A dual wavelength optical sensor for measuring chemical properties of a particular quantity, the optical sensor including a sensor probe having a thin sensing film whose optical characteristics are responsive to the chemical properties of the measured quantityThe United States Government has certain rights in this invention pursuant to Contract No. ITA87-02 between the U.S. Department of Commerce and Iowa State University.

Abstract: A dual beam spectrometer for conducting both turbidimetric and colormetric measurements includes a housing with a light source. The housing further includes source exit apertures that form light from the light source into a sample light beam and reference light beam. A sample cartridge for containing sample material to be measured is mounted in the housing in the path of the sample light beam. The spectrometer also includes a detector assembly for detecting the sample light beam and the reference light beam. The detector assembly includes a first detector that senses or detects sample light beam and a second detector that senses or detects the reference light beam. A sample light beam detection aperture tube is positioned in the housing between the sample cartridge and the first detector. Similarly, a reference light beam detection aperture tube is positioned between the sample cartridge and the second detector.

Abstract: Methods and apparatus for accurately determining the volume of a pipette using a photometer. A reagent system for use with the photometer includes a first container holding a reference solution and at least one second container holding a sample solution. A container holding the reference solution having maximum absorbance at a first wavelength is positioned in the photometer. The absorbances of the container at the first wavelength and at a second wavelength are measured. Then the optical pathlength of the container at the second wavelength is calculated from the measured absorbances at the first and second wavelengths. An aliquot of the sample solution is introduced into the container with a pipette to be calibrated. The sample solution has maximum absorbance at the second wavelength. The sample solution is mixed with the reference solution to form a mixture. Then the absorbance of the mixture in the container is measured at the second wavelength.

Abstract: A measurement device is provided for determining relative proportions of at least two materials forming a liquid and having different densities and different responses to light. A transparent capillary size cuvette tube confines the sample liquid, and is attached radially on a rotor wheel, preferably by a holder which seals an outer end of the tube and provides a package for manipulation of the tube without exposure to the sample. A motor controlled by a processor turns the rotor wheel, separating the materials by their densities. A linear light source illuminates the tube, and a linear array of photosensors defining pixels produces a signal which varies where the different materials abut. The pixels are counted, to locate the stratum between materials and the result is displayed as a percentage of total volume, suitable for hematocrit measurements. The cuvette tube has a fin for assisting in manipulation, is shaped as an elongated lens, and is cut to a spherical end surface to assist in sample collection.

Abstract: An arrangement for measuring the reflection and/or transmission of an object comprises a frame 1, a carrier 7 for the object, a radiation source 15 and a detector unit. The detector unit, which comprises one or more radiation-sensitive detectors 17A, 17B may be arranged on a holder 13 which is pivotable about a pivotal axis 13a. A slide 5, which is movable parallel to the pivotal axis, may be provided for moving the carrier and the detector unit rectilinearly towards and away from one another.

Abstract: A method and apparatus for analyzing fluid by a multi-fluid modulation mode is characterized by subjecting a plurality of sample fluids (which may be different or a single sample fluid divided into a plurality of systems) to a fluid modulation by reference fluids at various frequencies, respectively. An analytical portion provided with only one sensor is simultaneously and continuously supplied with the respective sample fluids. An output signal from the sensor in the analytical portion is divided into signal components of the respective modulation frequencies for the respective sample fluids to rectify and level, whereby obtaining analyzed values about the respective sample fluids is achieved.

Abstract: An optical method for monitoring the products of combustion, particularly for the detection of upset conditions in the incineration of hazardous waste, is disclosed. On-line detection of upsets is extremely important to avoid sending untreated waste out the stack plume and to avoid the formation of hazardous products of incomplete combustion, such as dioxins. Small hydrocarbons are the strongest candidates for in situ monitoring of combustion efficiency. The combustion is monitored via infrared absorption using tunable diode lasers (TDLs).

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 ink concentration sensor maintains ink concentration in an ink jet printing system. The ink concentration sensor includes a transparent fluid chamber and an infrared light source for directing a beam of IR light at the fluid chamber. A first sensor is located for receiving IR light reflected from the surface of the chamber and providing a reference signal and a second sensor is located for receiving IR light transmitted through the chamber to produce a concentration signal. A circuit receives the reference signal and generates a corrected concentration signal.

Abstract: A device is proposed for measuring the composition of fluids, in particular of constituents of exhaust gases from internal combustion engines, in which a light ray (32, 31) is used to irradiate the exhaust gas to be measured over the length of a measuring section (29) and is weakened or changed more or less, depending on the content of constituents. The light signal being received is advantageously registered by a measured length light receiver (18) which is shielded light-tight against the light emitting light source (14) and is evaluated in relation to the original light emission, in an evaluation circuit (26). In this simple way, accurate information is obtained of the exhaust gas clouding and of the loading of a fluid or gas with constituents which are optically active.

Abstract: A sensor and method is provided for measuring one or more select components of a material. In one embodiment, a method measures the components by emitting electromagnetic radiation at the material and detecting the intensity of the emerging radiation at separate locations from the source. In another embodiment, a sensor provides a radiation source for emitting radiation at a sheet, a plurality of detecting means, wherein at least one detecting means is offset from the source, for detecting radiation after interaction with the sheet and first and second reflectors for directing the radiation so that the radiation makes multiple interactions with the sheet when moving from the source to the detecting means. The invention can accurately measure the select components (e.g., moisture) of different grades of paper by eliminating the effects of the scattering power and determining absorption power at each band of the spectrum considered necessary for a particular measurement.

Abstract: A fiber optic fluid opacity sensor includes a light source (12) transmitting light to dividing means (14) for providing a sample light signal (18) and a reference light signal (20) to dual photodetectors (26, 28). Sample and reference optical pathways (19, 21) are defined by optical fibers (18, 20) spaced apart from and axially aligned with the photodetectors (26, 28) at a predetermined distance. Signal processing means (30) takes the log ratio output of the signals from the photodetectors (26, 28) for cancelling the effect of light source drift since the same source (12) is common to both for measuring the light transmission and determining opacity therefrom. A sample probe (40) contains the photodetectors (26, 28) and the sample and reference optical pathways (19, 21). The light source (12) and the signal processing means (30) are situated outside of the probe (40) and by virtue thereof outside of the sample process line (48).

Abstract: The invention is directed to a method of operating a laser diode in a measuring system for spectroscopically measuring the concentration of a gaseous component in a gas sample. This method is improved in that the mode jumps of the laser diode are easily recognized when adjusting the temperature-current operating point of the laser diode. An optical filter is placed in the beam path for adjusting the temperature-current operating point of the laser diode and, by changing the temperature T and the operating current I of the laser diode while simultaneously receiving the output signal supplied by an evaluation unit, the spectral positions of the mode jumps of the laser diode are determined which are included in the absorption lines of the gas sample. Thereafter, the temperature-current operating point is adjusted so that the distance of this operating point to the positions of the mode jumps is not less than a fixed spacing.

Abstract: A set of red light sources (111-113) are provided above a printed board (20). One (111) of the light sources located in the angular aperture of an imaging lens system (140). The red light is applied to the printed board and reflected on a wiring pattern (22) provided thereon. Another light source (120) is provided under the printed board, and emits infrared light to the back surface of the printed board. The infrared light passes through a through hole (25) formed in the printed board and then enters the imaging lens system together with the red light reflected. Compound light consisting of the red light and the infrared light passes through the imaging lens system and is then splitted into the red light and the infrared light at a cold mirror (150). The respective lights are detected by image sensors (161, 162), to thereby obtain respective images of the wiring pattern and the through hole.

Abstract: Methods and apparatus employing optical spectrometry techniques to measure metallic wear debris contamination in used motor oil, even in the presence of carbon particulates. Measurement results based on optical spectrometry as disclosed herein correlate closely with results of laboratory analysis based on atomic spectrometry. Variation in transmittance of a sample of oil as a function of wavelength within the approximate range of 300 nm (violet) to 1300 nm (near-infrared) is measured as an indicator of metallic wear debris contamination. Conveniently, measurements may be taken at just two wavelengths within the range, for example 565 nm (green) and 660 nm (red). The ratio of transmittance at the shorter of the two wavelengths to transmittance at the longer of the two wavelengths is determined as an indication of the amount of metallic wear debris contamination, decreases in the ratio from a ratio of unity indicating increasing levels of contamination.

Abstract: A measurement method is presented for the determination of low levels of optical absorption in any material, with at least a quasi-simultaneous detection of the transmission intensities of a measurement light beam and a reference light beam, the wavelengths of which are different, such that, essentially, the measurement light is absorbed by the material to be tested, and with a joint analog acquisition of the detected measurement and reference signals, taking into consideration the natural difference in intensities between the measurement light beam and the reference light beam.

Abstract: A double beam detector system for liquid chromatography includes a light source and slits to effect two beams of radiation symmetrical to an optical axis and focused through a common point. A concave reflective dispersion grating is disposed on the optical axis which is folded at the grating. A collimating lens directs the beams parallel to the optical axis into a pair of detector cells. The collimating lens and entrance lenses for the cells are selected so that the common point is imaged on exit windows of the cells. The grating has a curvature selected cooperatively with the collimating lens, entrance lenses and relevant distances so as to focus the entrance slits at respective entrance windows for the cells. The beam size is constricted to less than the cell bore size by selected parameters of the collimating lens and the entrance lenses.

Abstract: Method and apparatus for spectroscopic measurement of the concentration of a gas in a sample where you detect the intensity of light from a light source (1) passed through the sample (4) and through a reference cell (5) and generates a signal which represents the concentration of the gas. A laser diode (1) constitutes the light source which is locked to the absorption line of the gas at known concentration and pressure contained in a reference cell (5). The laser light with the properly selected wavelength is distributed via optical fibres (2, 3, 6) and/or glass prisms (19, 20) to the reference cell (5) and the sample (4). Non-gas-related transmission variations in the measurement path or in the optics is automatically compensated for by a special laser modulation which generates a time multiplexed reference.

Abstract: A compact high performance absorbance detector including a flashlamp light source and folded optics system with ruled grating reflecting beam splitter for minimizing flash to flash angular pattern and spectral variations of the flashlamp.

Abstract: A process and device for measuring the isotope ratio, specifically of stable isotopes, of chemical substances in a gas to be examined, the process including alternately charging a sample cell with a reference gas and a measuring gas containing the gas to be examined; adding a metrologically neutral gas to the gas to be examined; varying the mixing ratio of this measuring gas by changing the share of neutral gas being added; and calculation of the isotope ratio V.sub.p of the substance according to the equation: ##EQU1## The device includes a White cell having mirrors on each end of the longitudinal length of the cell, a pair of first beam openings located on a longitudinal end, a pair of second beam openings in spaced parallelism on the longitudinal sides of the White cell and a gas inlet and gas outlet located near each mirror.

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 improved transmissometer of the type which has a visible light source and is responsive to peak and mean spectral responses between 500 nm and 600 nm and optical assembly therefor contains a solid state light source preferably a light emitting diode. The light source emits a low level light beam that is split, part of which is passed through a gaseous sample then directed to a detector while the other part is directed to a second detector. Electronic components are provided to amplify the signal that has passed through the sample providing high gain, low noise amplification and use signals from the detectors to control the light source and determine opacity of the sample.

Abstract: There is provided a gas analyzer, including a radiation source, an analytical space through which passes the gas to be analyzed, at least one detector for detecting the intensity of radiation passing through the space, apparatus for facilitating the alternating introduction, into the space, of the gas to be analyzed and a reference gas having a concentration located at least in the upper half of the range of concentrations to be measured by the gas analyzer. The analyzer further includes processing apparatus, having a memory device, to process signals originating in the detector, the memory device adapted to store in a first mode of operation, signals representing instantaneous intensity values of the detected source and, in a second mode of operation, to store signals representing intensity values obtained when the analytical space is filled with the reference gas, a circuit for comparing the instantaneous values with the reference value, and an indicator device for indicating concentration.

Abstract: An optical examination apparatus for optically examining density, distribution, etc.

Abstract: The distance between two objects, such as aircraft, helicopters and other vehicles, can be determined by transmitting from a first object through atmosphere a first frequency which is absorbed by atmosphere and a second frequency which is not absorbed by atmosphere, receiving at a second distant object the first and second frequencies, and determining from the received first and second frequencies the distance between the first and second objects. In preferred methods and apparatus, the first frequency is a frequency characteristic of atmospheric oxygen absorption (e.g., 760 nm wavelength), and the frequency transmission comprises emitting a laser light beam while modulating its frequency through a frequency range which is greater than a frequency range characteristic of atmospheric oxygen absorption (e.g., 750 nm-770 nm wavelength) and includes a second frequency which is not absorbed by atmosphere.

Abstract: A nulling optical bridge is disclosed herein for the measurement of the difference in the relative power of more than one light beam. The bridge can be used to precisely measure the change in reflectivity and/or transmissivity of a semiconductor device or metal. The bridge operates by splitting at least one illumination source into a number of beams wherein one of said beams is made to traverse the sample whose change in transmissivity and reflection characteristics is to be measured. A rotating polarizer is used to equate the intensity of the variable and nonvariable beams under feedback servo control from a photodetector. The incremental quantity of rotation of the polarizer can be calibrated to correspond to a number of characteristics of the sample.

Abstract: A method of detecting undesired microorganisms when cells are cultured in a light permeable container is disclosed. TV camera monitors the image of a well containing microorganisms through a microscope. The output of the TV camera is processed by a picture digital processor so as to count the number of cultured living cells. On the other hand, change of the light absorption of the visible light by the cultured solution is measured. Then the number of undesired microorganisms can be calculated by the number of the living cells and change of the light absorption.

Abstract: A method and apparatus are disclosed for the in vivo and in vitro detection and measurement of dose critical levels of DNA-binding anti-cancer drug levels in biological fluids. The apparatus comprises a laser based fiber optic sensor (optrode) which utilizes the secondary interactions between the drug and an intercalating fluorochrome bound to a probe DNA, which in turn is attached to the fiber tip at one end thereof. The other end of the optical fiber is attached to an illumination source, detector and recorder. The fluorescence intensity is measured as a function of the drug concentration and its binding constant to the probe DNA.Anticancer drugs which lend themselves to analysis by the use of the method and the optrode of the present invention include doxorubicin, daunorubicin, carminomycin, aclacinomycin, chlorambucil, cyclophosphamide, methotrexate, 5-uracil, arabinosyl cytosine, mitomycin, cis-platinum 11 diamine dichloride procarbazine, vinblastine vincristine and the like.

Abstract: Titration apparatus includes two cells that receive and contain liquids and are transparent to light. A liquid having an unknown characteristic and mixed with an indicator that is optically responsive to a titrant is disposed in the cells. Light is transmitted through each cell to separate photosensors. The photosensor signals are compared and a titrant is added to one of the cells in known-volume increments until the difference between the signals reaches or exceeds a prescribed threshold. The characteristic of the liquid is calculated from the quality of known concentration titrant added in order to reach or exceed the prescribed threshold.

Abstract: Instrumentation for measuring the amount of material dissolved in a liquid solution which utilizes electro-optic technology based on the Beer-Lambert Law is implemented either as a portable, battery powered model or integrated in an automated process monitoring system. In the portable, battery powered model, a sample probe (14) is inserted into a solution to be measured. The results of the measurement are displayed on a display (22). The displayed results are frozen for a predetermined period of time at the expiration of which, the power is turned off to conserve battery power. In the automated process monitoring model, a solution loading analyzer (100) is supplied with a sample of solution to be analyzed. A probe (14) positioned in a measurement well (200) is used to determine the ratio of incident light to light transmitted through the sample. A spray nozzle (212) is used for cleaning the probe head (16).

Abstract: In an apparatus for determining the concentration of foreign matter in a water stream, a stream of liquid is bypassed through conduits both before and after the pipeline block for the process and each stream is pumped into a cell, a beam source being associated with each of the cells whose beams penetrate the cells and are led by a beam splitter both to a first detector and to a second detector, the electrical signals of the detectors being compared by an electrical circuit and processed to a recognition signal. To make a bubble-free sample stream possible, magnetically actuated valves are inserted into the return lines which are connected to the cells, and the signals for opening and closing the valves are produced by a frequency generator.

Abstract: The present invention provides a system for transmission loss comparison.On embodiment of the present invention compares the transmission losses through optical paths through a first solution and a second solution. This embodiment includes first and second light sources for transmitting light through the first and second solutions. Also provided are first and second light detectors corresponding to the first and second light sources, and comparison means for comparing the outputs of the two detectors in order to determine which solution is darker.In addition, this embodiment includes a common gain balance configuration means for calibrating the relative gain of the two light detectors in order to compensate for signal differences between each source/detector path arising from various mechanical or optical factors. Further included is a dark solution compensation bias to compensate for differences between each source/detector path arising from spectral differences between the two light sources.

Abstract: An extinct type detector which detects and determines a concentration or density of a gas or vapor in a space on the basis of an attenuation of light due to the gas or vapor present within the space.The detector of this feature of the invention operates in such a way that the light emitting device is periodically driven to effect light emission, the first and the second photodetector devices receive the light from said light emitting device, the first and second storage means corresponding to the first and the second photodetector devices, respectively, cumulatively store the outputs from the respective photodetector devices, a difference in cumulative storage values between the first and the second storage means is detected to determine a concentration and density of the gas or vapor within the detecting space based on the detected difference.

Abstract: An infrared heat source is directed through a chopper or modulator and beam splitter to the surface of the water. A pair of radiometers are provided, one located behind the back surface of the wafer to measure transmittance, the other adjacent to the beam splitter to measure wafer reflectance. The wafer temperature may then be calculated using an experimentally determined relationship between wafer radiance W.sub.W and wafer temperature, with wafer radiance being provided by the relationship ##EQU1## where r.sub.BS is the reflectance of the beam splitter, W.sub.W is the blackbody radiance of the wafer, W.sub.a is the blackbody radiance equivalent to ambient temperature, and e.sub.W is the wafer emittance. Alternatively, rather than locate a radiometer behind the wafer to measure wafer transmittance, a mirror may be located behind the wafer to reflect the transmitted energy back through the wafer on a periodic basis for a short part of each duty cycle.

Abstract: A device for analyzing the composition of the exhaust gas of an internal combustion engine in which a light source provides a light beam absorbable by the exhaust gas, and a plurality of measurement cells are traversed by radiation of the light beam while the exhaust gas flows through the cells. A corresponding number of radiation detectors are arranged after the measurement cells to receive the absorption attenuated light radiation and to produce an electrical measurement signal. At least one light interrupter periodically interrupts the light radiation.

Abstract: A comparitive colorimeter for use in the field which simultaneously compares the color densities of two liquid samples and designates the degree of difference. The apparatus includes two major subsystems, optical and electronic. The optical subsystem is designed to provide identical light beams through both the sample and standard solutions and to minimize the effect which imperfect sample tubes have on the output. The electronic subsystem includes a log conversion and differential amplifier circuit for generating a difference signal representative of the difference between the optical densities of the sample and standard solutions. The difference signal is evaluated by a comparative circuit consisting of a resistive chain having a plurality of node voltages and hex inverters connected to the node voltages. The hex inverters drive a series of LED indicator lights to designate the relative degree of difference between the optical densities of the sample and standard.

Abstract: Apparatus and method for optically measuring temperature by spectroscopically determining the temperature-induced changes in the wavelength spectrum of light interacting with a semiconductor temperature sensor. The method includes providing illumination from a radiant energy source with a broad wavelength spectrum, guiding the radiant energy to a remote semiconductor sensor, returning the radiant energy after interaction with the semiconductor sensor, and analyzing the returned wavelength spectrum to determine the temperature-induced spectral changes due to the absorption edge of the semiconductor sensor. One embodiment of the invention comprises a quartz-halogen lamp, an optical multiplexer, optical fiber lightguides, a gallium arsenide semiconductor sensor, a fast scan spectrometer, an analog to digital converter and a microprocessor for processing the information of the returned wavelength spectrum for determining and displaying the sensor temperature.

Abstract: To scan gels optically, a gel scanner includes a gel holder and an optical system mounted for motion with respect to each other. The optical system includes a tungsten halogen lamp, first aperture, second aperture, beam splitter and first and second light paths; the first aperture having a dimension in the direction of motion of the gel with respect to the optical system of less than 0.5 millimeter and a dimension in a direction transverse to the direction of motion of less than 10 millimeters. The lamp and first aperture are mounted on one side of said gel holder and the second aperture is mounted on the other side of said gel holder.

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: An optical measuring system for measuring in situ by means of one or more fiber-optic probes reflection absorption fluorescence, phosphorescence and turbidity of a fluid or (for all but the last measurement) of a fluid-solid interface. High intensity pulsed light is conveyed to the measurement site by a fiber-optic cable and is given a specific direction at the site by means of the geometry of the probe, reaction light resulting from the stimulating light pulse is discriminated by the geometry of the probe, or another probe, and is returned via a further fiber-optic cable to a measurement system which is enabled to sense the returning light only for the duration of the light pulse. The measurement system comprises means for sensing the relative intensity of the stimulating light pulse and for deriving a signal at least representative of the ratio of the magnitude of the quality sensed, by means of the probe, and the relative intensity of the stimulating light pulse.

Abstract: The system and the method of the present invention tests the homogeneity of a solution utilizing a housing which includes a first chamber for a reference solution and a second chamber for a test solution. The housing also includes a pair of transducers spatially related to the first and second chambers for providing signals in accordance with incident lights. The housing also includes a light source which provides light equally to both chambers in a manner so the light passes through the solutions in both chambers to be incident upon the transducers. Circuitry connected to the transducers provide an output signal related to the quality of the test solution in accordance with the signals provided by the transducers.

Abstract: An optical transmission factor is measured by using mutual measuring technology having a pair of identical units (44, 50) located on opposite sides of an object (A). Each of said units (44, 50) comprises a pair of beam splitters (47, 48), a light source means (45, 46) for illuminating an object (A) through a first beam splitter (47) and providing offset beam (56) from said first beam splitter (47), a photo-detector (49) for converting optical power from the other unit (50) and said offset beam (56), wherein each of said beam splitters (47, 48) is substantially in parallelogram shape with two pairs of confronting planes (24, 25; and 22, 23), first pairs of planes (24, 25) are not perpendicular to the second pair of planes (22, 23), one of first pair of planes (24) is mirror coated for reflecting the inside beam, so that split beams (29, 31) from single beam (27) share a common point (200) on the plane ( 23). Thus, a dust/soil free measurement with no mechanically moving means is accomplished.

Abstract: Method and apparatus for monitoring the purity of a liquid in a container by passing a laser beam divided into two portions with the first portion passing through a pair of quartz windows with the liquid in a container therebetween, and the second portion being directed through the two windows and the liquid, the first portion being detected to detect the amount of solid particles in the liquid, and the second portion being detected to determine changes in refraction index to obtain a recording of the purity of the liquid.

Abstract: The present invention relates to viewing a three-dimensional internal structure of a specimen. According to the invention, it is possible to observe the internal structure of a particular cross section of a specimen as clearly differentiated from the other cross sections. The characteristic features of the invention lie in that a plurality of light beams passing through different portions inside the specimen are used, and a correlation among the measurements of transmittance of the plurality of light beams is determined.

Abstract: An instrument for measuring opacity of oil mist for lubrication purposes is set forth. In the preferred and illustrated embodiment, the apparatus is preferably installed in a pipe cross, opposing legs of the cross conduct oil mist past the opposite two legs supporting an opacity measuring system. Utilizing a bridge voltage supply to power an amplifier forming a reference voltage for reference diodes, a first photo cell is provided with a reference light from LED created light directed to the reference. A second LED directs light through the oil mist. The quantity of light is measured by a second photo cell reflecting the light absorbence of the sample, and the output of the two measuring devices is determined in a differential amplifier, driving a meter movement. The direct current signal is at a safe current range for use of the transmitter in a hazardous environment and is inversely proportional to the percent transmission of the signal.

Abstract: A probe for detecting separated sludges such as in sewage, is axially elongated and has a large number of LED-phototransistor pairs axially spaced thereon in facing relationship with a gap therebetween. The phototransistors are commonly connected, and the LEDs are sequentially fired by multiplex switching located within the probe. Since the quiescent current of the phototransistors is normally low, the common phototransistor output will essentially be proportional to the amount of light reaching a specific phototransistor. The output signals are processed to automatically locate an interface between separated sludge and clarified liquor. Circuitry is included to adjust the power level at which the LEDs are activated responsive to the output from selected ones of the phototransistors, for the purpose of reducing beam intensity if the sludge becomes thin, and also for increasing the intensity to overcome fouling of the windows of the probe.

Abstract: An optical transmission monitor for determining the optical transmissivity and thickness of films deposited on a substrate. A monitor substrate in the form of a rotating disk exposed to the deposition process is used. An optical system for measuring the transmissivity of the disk obstructs a fixed segment of the rotating disk so that the film thickness on the monitor disk is a known fraction of the film on the substrate being processed.