Abstract: A method of calibrating and adjusting an apparatus for determining the fill level of a selected specific fiber material in a filling chute of a fiber storing device. The apparatus includes an optical device situated above an expected maximum fill level in the filling chute and having a light emitter arranged to direct a light beam from above onto an upper face of the fiber material and a light detector arranged to receive a light beam reflected from the upper face, a microcomputer, including a microprocessor, operatively connected to the apparatus for receiving detector signals from the apparatus.

Abstract: A fibre optic sensor, particularly for ascertaining fluid levels, utilizes at least two optical fibres having at least a portion thereof embedded in a transparent substrate material of similar refractive index. One of the fibres is coupled to a light source, the other to a light detector. The fibres are oriented in a plane relative to the interface between substrate and fluid so that light exiting the source fibre is coupled to the detector fibre when total internal reflection at the interface occurs in the presence of a first fluid. In the presence of a second fluid of higher refractive index than the first fluid there will be no coupling. Several different embodiments, to achieve discrete or continuous level sensing or the sensing of other parameters are disclosed.

Abstract: An air bubble sensor device comprises a sensor block and a recess in the block for receiving a hollow tube through which liquid flows. The tube has an interior surface and an exterior surface. A light source is arranged in the block to direct light at the tube when placed in the recess. This arrangement permits light rays to strike the interior surface at an angle with respect to the normal of the interior surface. A light detector is arranged in the block to receive a light reflected at the interior surface when an air bubble is present in the tube. The light detector is positioned to receive substantially no light refracted at the interior surface when liquid is present in the tube. A mechanism is provided for taking the light received by the detector to produce a signal for indicating the presence of an air bubble in the tube. A method for detecting the presence of an air bubble in liquid is also within the purview of the present invention.

Abstract: An apparatus to indicate a low level of liquid in a vessel, such as an automobile crankcase. A light-emitting diode and a phototransistor are coupled at the crankcase so that the light received by the phototransistor varies with rising or falling oil levels. The diode has a given maximum current rating. A unique pulse generating circuit applies a short duration, high-current pulse to the light-emitting diode to produce a correspondingly short but intense burst of radiant energy that is received by the phototransistor. The sensitivity of response is superior to that of a phototransistor employed with a light-emitting diode driven by low-level voltages giving rise to currents equal to or less than its steady-state rating. False readings are eliminated when the vehicle is on an incline, or when the ignition switch is improperly operated. Reliable functioning is had, even at high operating temperatures.

Abstract: An elongated level sensor system has an optical prism formation moulded or ut in a side, and includes a plurality of LED light sources and corresponding photocells positioned along its length. Light from the LED sources are reflected off the prism surfaces to respective photocells when there is no liquid present in the area, thereby indicating "no liquid media present." When liquid surrounds a particular section, light from the LED is not reflected from the prism surfaces, but is refracted out; the change in photocell voltage then indicates the presence of liquid media. The system can be used in a plurality of liquid storage areas, and read out simultaneously at a remote sensor/alarm panel.

Abstract: An air-in-line detector for use with an IV administration system comprises a light emitter positioned relative to a plurality of light sensors for receiving an IV tube therebetween. A comparator is connected with the light sensors to determine the relative intensity of light respectively incident on each sensor. Means connected with the comparator generates signals in accordance with the relative intensities to indicate whether an IV tube is present and, if so, whether there is fluid or air in the tube.

Abstract: A device for measuring the level of liquid fuel in a tank of the type in which one marks the hollow distance between the surface of the liquid and a horizontal reference plane made near an opening that gives access to the tank. The device includes a depth gauge containing a reference base, a mobile rule and means for measuring the relative displacement of the rule relative to the base; means for support against the reference plane of the tank integral with the reference base of the gauge; an optical probe containing static means for detection of liquid at a predetermined level and means for display that can indicate the presence or absence of liquid at this predetermined level, this optical probe being integral with the mobile rule of the gauge.

Abstract: A liquid monitoring system includes chamber structure with a monitoring region in which the liquid to be monitored is disposed, the monitoring region having two spaced wall portions and a supplemental wall portion. The system further includes a radiation source mounted adjacent one of the spaced wall portions or directing a beam of radiation along a horizontal path, and a sensor mounted adjacent the opposed wall portion for receiving radiation in a beam path. The incident radiation beam as it passes through the wall into the monitoring region is refracted at the region surface as a function of gas or liquid within the region. At a first refracting angle, the refracted beam impinges on the supplemental wall and is internally reflected, the reflected radiation passing along a reflected beam path and sensed by the detector to provide an indication of the fluid in the chamber. At a second refracting angle, the refracted beam is not reflected in a direction such that radiation from the source is sensed.

Abstract: A liquid level gauging system and sensor device for installation in the aperture of a wall of a liquid-containing vessel, including a metal fitting having a through bore and a substantially cylindrical body portion with external threads by which it can be secured in the aperture in the vessel wall, a cup-like enclosure disposed in the bore, the enclosure having a bottom wall containing a prism disposed adjacent the inner end of the bore, and a light source and a light-responsive device mounted in the enclosure. The prism has a substantially conical forward end portion for immersion in the liquid to be monitored. The conical forward end portion of the prism is characterized by an axis, and the prism has a light-admitting and light-transmitting conical recess coaxial with the conical end portion of the prism. Light rays from the source that pass into the surface of the conical recess are bent, by refraction, toward the conical end portion.

Abstract: A transducer to measure pressure or temperature comprising a quantity of compressible material such as gas and a quantity of incompressible material such as liquid and proper means (16,17) to detect volume and interface(s) (14) changes of said compressible material induced by pressure or temperature variation. Radiation may be used to detect said changes. Both source (16) and detector (17) of radiation may be separated from said compressible and incompressible materials using appropriate waveguides (10,11) thus allowing for transducer miniaturization. The only deformable element of the transducer is said compressible material, every other part of it being substantially rigid this feature offering robustness and simplicity of construction. Provision is made for the in-situ calibration and flushing of the instrument when required.

Abstract: An apparatus for measuring the diameter of a crystal in which an optical sensor scans along a sensing line which crosses at one point a luminous ring formed at the interface between a crystalline rod and a melt; the picture element position corresponding to a maximum luminance is discriminated when the optical sensor scans; the mean value of the picture element position is calculated over at least one revolution of the crystalline rod; and the diameter D of the crystalline rod at a portion thereof interfacing with the melt is calculated from the mean value and the level of the melt. Similarly, the minimum crystal diameter can be calculated by obtaining the picture element position corresponding to the minimum crystal diameter instead of obtaining the mean of the picture element position.

Abstract: A liquid removing attachment (22,24) for a fiber optic photoelectric sensor (14) that is used in a wet environment such as near a workpiece or tool (20) that is being sprayed or flowed with a liquid coolant. Such coolant produces an ambient mist or splash of liquid at the adjacent end of the fiber optic cable (16,18) which condenses or accumulates as a liquid mass or drops (6) on the exposed end of the optical fiber bundle (7) tending to interfere with light transmission therethrough. The attachment (22,24) provides radial channels (8b-e) adjacent the exposed ends of the optical fibers (7) that through adhesion of the liquid thereto together with the force of gravity cause such liquid mass or drops (6) to flow away thereby to reduce the liquid accumulation in the light transmission path.

Abstract: A sensor for detecting liquid at a predetermined level in a container, including an emitter, a receiver sensitive to the emission of the emitter, a support member positioned at the exterior of a region of the wall of the container transparent to the emission with, the emission of the emitter so disposed in relation to the interior surface of the wall region of the container that when the region is a container/liquid interface then emissions from the emitter generally in the direction of the emission axis will pass through the interface and will be dissipated in the liquid, but when the interface is a container/air interface such emissions will be totally internally reflected from the interface.

Abstract: A linear digital flow meter includes a float in a passageway as is located positioned with the rate of flow. A sight glass tube is secured to the end of the unit and a rod connects the float to a tube. A generally H-shaped housing has the tube located in an opening in the cross bar with a light chamber to one side and a detector chamber to the opposite. A bank of LEDs in the light chamber is aligned with a transmitting slot and a bank of phototransistors is aligned with a receiving slot in the detector chamber. A shadow mask between the phototransistors and the slot concentrate the light so the phototransistor receive light according to the length of rod in the sight glass. A bottom connector chamber is in the bottom of the housing with L-shaped passages to the light and detector chambers with the appropriate leads to the lamp and detector chambers. A multiplexer connects the phototransistors to a microprocessor which stores and processes the signal.

Abstract: An optical fluid sensing apparatus comprising a sensing tip having a conical configuration with a coating, such as a thin layer of polytetrafluoroethylene (PTFE), on the outer surface of the tip element itself. At the sensing tip, emitted light is either refracted back into a detector fiber optic cable or is lost, depending upon the relationship between the indices of refraction of the sensing tip and coating to the substance surrounding the sensing tip, i.e. the fluid or air being sensed. In order to obtain the proper relationship between the sensing tip and the fluid, the index of refraction and the bevel angle of the tip element are carefully selected in relation to the indices of refraction of the coating and the fluid to be sensed. As a result, when fluid surrounds the tip light is dispersed into the fluid and lost. When no fluid is present, however, the coating sheds any remaining fluidand the light is internally reflected and refracted back into the detector fiber optic cable.

Abstract: The principal of total internal reflection is utilized in sounding an alarm in a medical fluid infusion system when a downstream blockage occurs. A miniature prism is mounted in a cavity in a rigid exterior tube. The infusing fluid flows in a plastic tubing along the central channel of the rigid tube. The plastic tubing in the interior of this exterior rigid tube is diametrically expansive with an unpressurized outside diameter which is less than the inside diameter of said rigid exterior tube. A light source and light detector is positioned adjacent to the equilateral planes of the prism mounted in the rigid tube.

Abstract: A method of detecting liquid leakage from a wall portion of apparatus and/or tubes containing a liquid. A cover member is attached to an outer surface of the wall portion to form a space defined between the cover member and the wall portion, and an optical fiber is inserted into the space through a hole in the cover member. A light beam is supplied through a palarized beam splitter to the optical fiber such that reflected light from the end of the optical fiber is measured, and the presence of leakage is determined in accordance with the amount of reflected light.

Abstract: A liquid drainage system comprising, a container having a cavity to receive the liquid. The system has an array of a plurality of associated pairs of light emitters and light detectors disposed generally vertically along the container. Each of the associated pairs of emitters and detectors are changeable between a first state with the light from the emitters impinging upon the associated detectors, and a second state with the light from the emitters passing away from the associated detectors dependent upon the presence of liquid in the container between the emitters and detectors.

Abstract: A non-metallic fiber-optic device is provided for measuring the level of fluid in a tank, reservoir, or other vessel. Light from a broadband light source is transmitted through a fiber optic waveguide and an optical coupler to an optical pipe sensor which is immersed in the fluid to be measured. The optical pipe sensor includes a monotonically varied diffraction grating in the surface and along the length of the sensor which serves to retroreflect wavelengths of light as a function of the local spacing of the diffraction grating. For light entering the sensor from the waveguide, wavelengths of light corresponding to the local spacing of the diffraction grating above the fluid level are retroreflected, whereas wavelengths of light corresponding to the diffraction grating spacing below the fluid level either escape into the fluid, are absorbed, or are coupled to a return fiber to be detected.

Abstract: A hollow dipstick is provided for immersion in molten material to determine the temperature of the molten material at any desired depth. The hollow dipstick is connected to an infrared detector by means of an optical fiber bundle for producing a signal indicative of the temperature of the molten material. An infrared focusing lens is provided within the hollow dipstick for transmitting the infrared radiation from the interior bottom surface of the dipstick to the fiber optic bundle. A container having a heating element therein is provided for receiving the dipstick when it is not in use so as to preheat the dipstick to a temperature close to the estimated temperature of the molten material to be measured to thereby prevent thermal shock to the dipstick upon immersion in the molten material. Alternatively the infrared detector is mounted directly on the dipstick.

Abstract: A method for detecting a liquid level is monitored at mutually opposing sides of a liquid containing bottle. For monitoring the liquid level at each side of the bottle, a diffused light beam is irradiated toward the liquid surface from a level below the liquid surface. The light reflected at the liquid surface and the light refracted at the liquid surface are detected by a photo-receiving camera which is focused at a standard liquid level. An average value of the monitored liquid levels at both sides is taken as a liquid level indicative value. By employing the aforemention method, accurate detection of the liquid level becomes possible even when the liquid level is unstable.

Abstract: A displacement sensor employs a light conducting member containing a fluorescent material. A source of irradiating light is movable relative to the light conducting member along a track. The irradiating light produces fluorescence within the member at a corresponding position. Light from the fluorescent point is conducted in both directions along the member and can thus be collected at one end for feeding to a photo detector. By monitoring variations in the intensity of light at the detector, the distance of the fluorescent point from the end of the member can be measured, and thus movement of the source along the track monitored. Additional embodiments enable dependency on the intensity of the irradiating light source and on losses between the light conducting member and the photo detector, to be mathematically eliminated.

Abstract: A sensing head for sludge detectors for use in effecting accurate sludge level detection in settling tanks, clarifiers, digesters, and the like, wherein the head that serves as the device probe comprises a cylindrical housing centered on its longitudinally extending axis and defining a reentrant indentation at one side of the head which extends toward the head other side beyond the longitudinal axis and defines a pair of opposed upper and lower housing walls and a gap therebetween, with such walls respectively having a light source and a light sensitive device, both separately lens covered and field replacable free of tool use, and in electrically connected relation with the detector cable of, for instance, portable detectors, to which cable the head is separately connected, for make-break light principal operation when the head is submerged in use; the head housing has upper and lower end caps sealingly secured thereto, an elastomeric bumper mounted on the lower end cap to protect the head lower end and side

Abstract: The invention relates to an optical probe comprising an optical means (5) having a given refractive index. This optical means is able to reflect an incident light beam if it is located in a medium (3), whose refractive index is higher than the given index and is able to reflect the incident light beam if it is in a medium (2), whose index is below the given index. The optical refraction or reflection means (5) is a cone of revolution, the axis (X) thereof being parallel to the incident beam (6) and to the optionally reflected beam (11), the base (12) of said cone receiving the incident light beam and is perpendicular to said incident light beam and to the possibly refracted beam. The cone and at least part of the optical fibres transmitting the incident and reflected light beams are located in a tight box or case. Application to the detection of interfaces of different media and to the determination of the components of a two-phase medium.

Abstract: A sensor for the measurement of the refractive index of a fluid and/or phase boundary between two fluids comprises a light guide in the form of a rod; one end of the rod is connected to both a light source and a detection element and the other end of the rod is reflective. If the sensor is used in a refractive index gauge the measurement should be independent of the liquid level; if the sensor is used in a level gauge, a digital measurement should be possible. The coating is provided with one or more cut-outs consisting of windows which are in direct contact with the surrounding fluid.

Abstract: A photoelectric bin level sensor comprising a housing from which projects a source probe and a detector probe, the source probe and the detector probe both are bent at an angle of approximately 100 degrees so as to point substantially downward. Said probes project from the housing and are located closely adjacent to the lower edge thereof so that probes can be conveniently passed through two holes drilled in a wall of a particulate matter storage tank.

Abstract: An empty container detector for use with a drip chamber comprises a photoelectric transducer associated with the fluid container which generates a variable control signal to alternately indicate whether the light path of the photoelectric transducer is being refracted by a fluid. A second photoelectric transducer is associated with a fluid container above the fluid level in the container to establish a reference signal which is modulated by drops falling into the container and which has a component corresponding to the condition wherein the light path is not refracted or attenuated by the presence of a fluid. Electrical means are provided to connect the first photoelectric transducer to the second photoelectric transducer to linearize and normalize the reference signal with the control signal.

Abstract: An electro-optical liquid detector assembly comprises a support block having a flat front surface attached to the internal surface of a wind-shield and being formed therein with a pair of inclined bores opening toward the internal surface of the wind-shield, a transparent flat plate contained within the support block and fixed to the support block to form a common flat front surface with the support block, the transparent flat plate being formed in its rear surface with a pair of spaced v-grooved portions which are opposed to the inclined bores, a light emitting element disposed within one of the inclined bores to emit a beam of light into the wind-shield through one of the v-grooved portions of the flat plate so as to cause internal reflection of the beam between the external and internal surfaces of the wind-shield, and a light receiving element disposed within the other inclined bore to receive the incident beam reflected by the external surface of the wind-shield through the other v-grooved portion of the

Abstract: An ink jet recorder includes an ink acceptor having an ink absorber arranged to face an ink jet head, and a detector for detecting the degree of absorption ability of the ink absorber. When the detector detects the loss of absorption ability of the ink absorber, it issues an alarm signal.

Abstract: A measuring device includes means for converting a physical quantity to be measured into a corresponding magnetic field. A magnetooptic element is aligned with a polarizer which passes incident light in one plane only. The part of the magnetooptic element which intercepts the transmitted magnetic field rotates the throughgoing light and the position of rotation is indicated on an optical indicator.

Abstract: The invention is directed to the use of magnets and fiber optics for detecting fluid flow and fluid levels. In general, the invention employs a permanent magnet movable by fluid flow or by the change of fluid levels which directly influences the degree of light transmission between a light transmitting fiber optic cable and a light receiving fiber optic cable. The light can be varied discreetly by shutter means or linearly varied by light reflection determined by distance or by varying the degree of reflection from a reflective surface. The received light information can be used for detectors, indicators, controls or the like.

Abstract: Liquid level indicator in a tank of the type having a total-reflection optical sensor (1). The sensor is mobile vertically, so as to be able to be immersed or partially immersed in relation to the liquid level. The optical sensor (1) has an integrated light transmitter (DE) and receiver (PR) and is suspended by a non-extensible cable (5) wound onto an upper drum (6), the drum being driven upwards or downwards by a stepping motor (9) relative to the liquid level. The sensor (1) is connected with a wire (10) through a pully (13) ballasted with a weight (14) and fastened at its upper end so as to provide both the mechanical tension of the cable (5) and the electrical connection of the mobile sensor (1). The indicator also comprises a magnetic sensor (16) co-operating with a magnet (17), one of these two units being fixed in the top position and the others being mobile with the cable (5), so as to detect the arrival of the sensor (1) at a given higher level or maximum liquid level.

Abstract: A photoelectric leak detector system for double-walled tanks and the like including a pair of optical fibers extending substantially from the top to the bottom of the annulus of the double-walled tank, a glass plate in contact with the lower ends of the optical fibers and spaced from the bottom of the annulus, a light source juxtaposed to the upper end of one of the optical fibers to pass light therethrough, and a photodiode juxtaposed to the upper end of the other optical fiber to detect changes in the reflected light issuing therefrom.

Abstract: A method and apparatus are provided for measuring the level of a surface of a material in a tank. The apparatus and method modulate an optical radiation beam at a radio frequency. The radiation beam is transmitted to the surface and the reflected beam received. The modulation frequency is changed until the phase of the received beam is the same as that from an optical reference path. The optical reference path is any fixed length path that allows the beam to pass from the source of the beam to the receiver that receives the reflected beam. An optical switch determines whether the receiver receives the reflected beam or the reference beam. The change in modulation frequency may then be correlated with the level on the material's surface in the tank.

Abstract: Two tubes of thermo-plastic material are joined by a sleeve in an inner portion of which there is an electrical resistance coil, the ends of which are connected to terminals projecting from the outer surface of the sleeve. An electrical circuit supplies electric current to the coil to heat an inner weld zone to welding temperature, while leaving enveloping outer portions at lower temperature. In the sleeve there is provided a radial hole or recess into which the heated material expands upon reaching welding temperature. The material expanding into the hole or recess when welding temperature is reached is sensed by a pressure responsive micro-switch or electro-optically by an optical transmitter and receiver and through a control circuit, shuts off the power to the resistance coil. The parts being thereby fused together, are allowed to cool to complete the weld.

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 opto-acoustic fuel quantity gauging system, including: a tank; an ultrasonic energy source; an optical power source; a fiber optic cable; an ultrasonic sensor; an optical detector and a signal conditioning circuit. The ultrasonic energy source is connected to the tank. The ultrasonic energy sensor is connected to the tank. The optical power source is connected to the fiber optic cable. The ultrasonic energy source is connected to the fiber optic cable. The ultrasonic energy sensor is connected to the optical detector by the fiber optic cable. The circuit is connected to the optical detector.

Abstract: Apparatus for determining the stability of a foam comprising a light source (1), a foam sample cell (2), a light sensitive cell (3) having a linear output voltage- or current-exposed area relationship, a voltmeter or ammeter (9) connected to the light sensitive cell (3) and a device (11) responsive to the output from the voltmeter for integrating a voltage-time curve or a current-time curve directly and dividing this area by the difference in voltage or current between that observed in the absence of foam and that observed immediately after foam has been formed to give the average foam lifetime. The light source (1), the foam sample cell (2) and the light sensitive cell (3) are positioned in line and are enclosed in a light-tight box (4).

Abstract: A sensing head for sludge detectors for use in effecting accurate sludge level detection in settling tanks, clarifiers, digesters, and the like, wherein the head that serves as the device probe comprises a cylindrical housing centered in its longitudinally extending axis and defining a reentrant indentation at one side of the head which extends toward the head other side beyond the longitudinal axis and defines a pair of opposed upper and lower housing walls and a gap therebetween, with such walls respectively having a light source and a light sensitive device, both separately lens covered, in electrically connected relation with the detector cable of, for instance, portable detectors, to which cable the head is separately connected, for make-break light principal operation when the head is submerged in use; the head housing has upper and lower end caps sealingly secured thereto, an elastomeric bumper mounted on the lower end cap to protect the head lower end and sides from damage, a lens guard mounted in the

Abstract: An optical liquid level sensor utilizing both a prismatic member for the light refraction when immersed in and surrounded by a liquid and its effects for the indication of the presence and absence, selectively, of the liquid level. This level indication is provided in the subject case through a target plate bearing letter codes and legends, respectively, which are recognized and standardized in this trade and which become visible at the onset and for the duration of an acceptable liquid level situation; otherwise; a messageless image appears in the sensor. The illuminated target plate allows also for the observation of the color and any color change of the liquid and the taking of remedial actions.

Abstract: A device for sensing the refrigerant level in a receiver tank and thereby detecting the surplus or shortage of the refrigerant in the tank is provided. The sensor device has a photoconductor a part of which is placed in the receiver tank. A light source is disposed at one end of the photoconductor and a light receptor element is disposed at the other end. The quantity of light passed from the light source to the receptor element through the photoconductor is changed as the photoconductor is dipped in the refrigerant in the tank. The surplus or shortage of the refrigerant in the tank is detected from the change in quantity of light received by the receptor element.

Abstract: An empty container detector comprises a photoelectric transducer associated with the fluid container which generates a variable control signal to alternately indicate whether the light path of the photoelectric transducer is being refracted by a fluid. A second photoelectric transducer is associated with the fluid container above the fluid level in the container to establish a reference signal corresponding to the condition wherein the light path is not refracted or attenuated by the presence of a fluid. Electrical means are provided to connect the first photoelectric transducer to the second photoelectric transducer to linearize and normalize the reference signal with the control signal. A comparator is associated with the photoelectronic transducers and connected to an alarm which indicates when the control signal is substantially equivalent to the reference signal and thus indicating the lowering of the fluid level below the light path of the first photoelectric transducer.

Abstract: In a method and apparatus for measuring the depth of a flowing fluid, and controlling the flow rate of the fluid based upon the depth measurement, the fluid is caused to flow through a conduit, where it is irradiated with a known intensity of light, and the fluid is caused to fall from a horizontally directed exit terminus into a reservoir having a reflective bottom. The fluid serves as a wave guide for the light it received within the conduit, and releases the light within the reservoir. The intensity of light reflected from the bottom of the reservoir and emergent from the fluid is directly proportional to the depth of the fluid in the reservoir, and is measured by a photodetector which transmits a control signal to a valve in the conduit.

Abstract: A non-invasive photoelectronic device which determines the location of a liquid column within a transparent tube. The device includes a source of visible light, transmitted as a substantially parallel light beam against a transparent lensing tube which may be a sightglass or a leg of a U-tube manometer located within the light beam. The liquid contained within the tube forms an identifiable liquid column which acts as a highly effective condensing lens to the transmitted light beams with a resultant focus close to the tube. A plurality of optoelectronic detectors are arranged in an array over the portion of the tube to be monitored. Each detector is a phototransistor which is responsive to the large change in light intensity caused by the lensing effect of the liquid-filled tube compared to the non-lensing action of the adjacent portion of the tube.

Abstract: A windshield moisture detector has two identical, symmetrically positioned prisms with an elongated body between an integral reflector and light transducer cavity. One light transducer cavity contains a light source and the other a light detector. The reflectors are angled so that when the moisture detector is partially in contact with the windshield, light can travel between the two reflectors through a light path in the window. The magnitude of light transmitted through the windshield is indicative of moisture on the windshield.

Abstract: An optical sensor is made of light transmissive material and has luminescent particles distributed throughout its volume. The luminescent particles are excited by a suitable type of energy, preferably light. As they return to their original state, they emit light uniformly in all directions. Depending upon the relationship of the index of refraction of the sensor body material to that of a test medium abutting a boundary surface of the sensor body, part of the luminescent light is reflected, the remainder passing into the test medium with a change in direction (refraction). When the test medium is optically less dense than the sensor medium luminescent light incident on the boundary surface at an angle exceeding the critical angle undergoes total reflection. For an elongated sensor body, this totally reflected part is transmitted to the end faces of the sensor, where its intensity constitutes a desired measure of a physical quantity.

Abstract: A fluid level and condition detector system including a multimode optical waveguide for insertion into a medium including at least a first fluid whose level is to be monitored, a source of radiation for introducing into one end of the waveguide radiation in a plurality of modes, and means for detecting the difference in radiation flux transmitted by the waveguide with the waveguide covered by the first fluid over its equilibration length, with the waveguide covered by a second fluid of lower index of refraction over its equilibration length, and with the waveguide covered partially by each fluid over its equilibration length and for detecting the difference in radiation flux transmitted by the waveguide due to the combined effects of the change in index of refraction and change in optical absorption coefficient of the first fluid covering at least a portion of the waveguide.

Abstract: A device for determining the position of the boundary between first and second substances having different refractive indices that may be used to determine the level or volume of liquid in a container. The apparatus comprises a plurality of optical sensors (21-26), a pulse source (30) for generating an optical source pulse, an interface (40) responsive to the source pulse for producing an optical response pulse, and a receiver (60) for measuring the duration of the response pulse. The sensors are positioned along a line that intersects the boundary (16) between the first (18) and second (12) substances over a range of boundary positions. Each sensor is adapted to vary one of its optical properties depending upon whether it is in the first or second substance. The interface produces the response pulse such that the response pulse has a time duration proportional to the number of sensors that are in the first substance.

Abstract: A light source to project a light beam along an axis to a receiver means intermediate the source and the receiver to cause the light to refract so that the light reaching the receiver is substantially reduced; means to periodically introduce a quantity of liquid into the area where the light is refracted, the liquid changing the amount of refraction whereby the light reaching said receiver is substantially increased; and means to detect each said change in light at said receiver and count same.

Abstract: A liquid level gauge including an elongate support member, and, a plurality of optical fibres carried by the support member, said fibres extending on the support member generally lengthwise thereof and generally parallel to each other, said fibres being spaced apart from each other circumferentially of the support member and each fibre being divided at a point along the length of the support member by a gap so arranged that the transmission of the light across the gap from one part of a fibre to the other part thereof is determined by the presence or absence in the gap of the liquid being gauged, the gaps of the fibres being spaced lengthwise of the support member.