Abstract: Methods, materials and devices for the remote measurement of physical variables with fiber optic systems use a single excitation light source for generating through the use of at least one luminescence converter, both a signal beam and a reference beam, and allow the transmission of both beams through a single fiber to a single photodetector, thus producing photo-electric signals the relative intensities of which are only minimally affected by changes of the intensity of the interrogating light beam, optical losses, or detector drift. In contrast to the prior art, the luminescent materials of this invention can be used either as transducers for physical parameters or as means for processing information from other optical transducers, without requiring a change in the luminescence properties of said materials under the influence of the measured parameter.

Abstract: A fiber storing device includes an inlet for charging the device with fiber material and an outlet for withdrawing fiber material therefrom. The fiber storing device is associated with an apparatus for determining the fill level of fiber material in the storing device. The apparatus has an optical device which comprises a light emitter and a light detector and which is situated above an expected maximum fill level of the fiber material. The light emitter is arranged to direct, from above, a light beam onto an upper face of the fiber material and the light detector is arranged to receive a light beam reflected from the upper face of the fiber material.

Abstract: An optical liquid level sensor has an optically-transmissive body (28) provided with a frusto-conical tip end portion (32). When the tip end portion is exposed to air, the angle of incidence (.theta..sub.i) of light at each of three points of reflection (b,c,d) is less than the critical angle (.theta..sub.c) such that substantially all light transmitted through the body will be reflected internally. However, when the tip end portion is exposed to a liquid, light is refracted, and the intensity of the reflected light is reduced. The intensity of the reflected light is used to indicate whether the sensor is above or below the surface of the liquid.

Abstract: A fibre optic sensor, particularly for ascertaining fluid levels, utilizes two cylindrical lightguides with regular perturbations to emit and/or accept light in a radial direction. Each waveguide is coupled to one (or more) light source and/or to one (or more) light detector. A light source such as a light emitting diode or laser diode is coupled to the lightguide which emits radially, illuminating a planar dielectric surface, which in the presence of a fluid with a low index of refraction, e.g. air, behaves as a mirror, coupling light via total internal reflection to the lightguide which accepts this light radially and channels the light to a light detector. In the presence of a fluid with a high index of refraction, for example water, at the planar dielectric surface the fluid dielectric interface becomes primarily transmissive, with relatively little light being coupled to the lightguide which accepts light radially.

Abstract: A probe is disclosed, for lowering into a water-well or other hole. The probe includes conductivity measuring electrodes, to distinguish between e.g., water and contaminants, such as gasoline. The probe also includes an optical sensing facility to locate the junction between air and liquid. The probe comprises a transparent plastic tube, mounted inside a housing. A beam of light from a LED passes obliquely through the plastic tube and onto a photo-transistor. When liquid is encountered in the well, the liquid enters the tube: the change in refractive index now directs the beam away from the photo-transistor. The optical and conductivity sensors are both actuated at the same depth.

Abstract: Liquid level monitoring apparatus for monitoring the level of a liquid in a container having a wall with an exterior surface and an interior surface and formed of a material which is substantially transparent to optical energy and which has an index of refraction different from that of the liquid. The apparatus comprises an optical sensor holder and adhesive means adapted to secure the sensor holder to the exterior surface of the container at a predetermined level. A sensor head is provided. An attachment mechanism is carried by the sensor head and the sensor holder for detachably mounting the sensor head on the sensor holder. A self-contained power supply is provided which is coupled to the sensor head.

Abstract: A liquid level sensor comprises a light source in the form of a semiconductor device, a light sensor also in the form of a semiconductor device, and an optical element arranged to transmit light from the light source and to receive reflected light and transmit it to the light sensor, the liquid level sensor further comprising a carrier having gas-filled cavities means in which the light source and the light source and the light sensor are respectively mounted, the cavities being separated by barrier means to prevent scattered light reaching the light sensor from the light source. The mounting of the light source and light sensor in gas-filled cavities extends significantly the operating temperature range of the liquid level sensor.

Abstract: A failure protected optical fluid monitor is disclosed that uses, in combination, a single prism paired systems of light sources and light detectors to determine whether or not liquid in a container is present at a predetermined level. A pair of light sources and coordinated photodetectors are fitted behind the flat end of a conical prism and each light source is adapted to direct a beam of light through the flat rear surface of the prism onto an angled face of prism. If a liquid is in contact with the conical surface of the prism, most of the light is refracted at the prism's surface and exits into the liquid. Under these conditions the light detector are not activated. If no liquid is in contact with the conical surface of the prism, the light beams will be totally internally reflected at both conical surfaces of the prism and will exit on the opposite sides of the prism from the light source parallel to its initial direction. Each light beam is then detected by a photodetector.

Abstract: The basic concept of the fuel gauge of this invention is to make use of the difference in refraction of liquid and air by means of optical fibres. More particularly, the fuel gauge includes a first set of optical fibers connected to a light source, a second set of optical fibres connected to a display unit and an optical medium mounted between the first and second sets of the optical fibres in such a manner that the light transmitted through the first set of the optical fibres is allowed to enter the second set of the optical fibres only through those optical fibres which are submerged in fuel. The light transmitted to the second set of the optical fibres may be converted into a visual signal with an existing display mechanism.

Abstract: A quantitative dispenser for a liquid includes a pipette having a downwardly directed nozzle which serves to pick up and deliver a predetermined quantity of a liquid and a mechanism for moving the pipette downwardly to dip the lower end of the pipette into the liquid supply. A detector is provided for detecting reflection of light which is projected downwardly to the surface of the liquid while the pipette is moved downwardly to approach the surface. A control circuit is connected to the detector to determine the stop point for the downwardly moving pipette with the aid of information received from the detector. The detector is provided with a spot type reflection sensor having a light convergent optical element having a focal point at a certain distance below the detector whereby the stop point of the downwardly moving pipette is determined so as to correspond to a point of maximum intensity of the incoming reflected light.

Abstract: A control unit maintains the fiber flock column in a feed chute at a set height. The control unit includes a row of light barriers located about a set height for emitting signals in response to interruption of the light barriers by fiber flock. An evaluation unit evaluates the signals to determine the actual height of the flock column and emits a control signal to adjust the feed rollers in the feed chute.

Abstract: An fiber optic liquid level indicator with a floating reflector includes a reference scale provided with a reflector disposed in an upper space above the liquid level within a pressure vessel so that a reference distance usable to correct error due to pressure can be calculated on the basis of travel time of a laser beam pulse emitted from a laser generator and reflected from the reference scale reflector through an optical guide and lens. A beam change-over switch is used to selectively guide a laser beam pulse to either the floating reflector or to the reference scale reflector so that pulse travel time can be determined.

Abstract: An optical sensor for converting a physical value into an electric output signal comprises a light source from which a beam of light rays is coupled into a first surface of a photoconductive body. The light rays are totally reflected by one boundary surface of, or coupled out from said body in response to a given physical value. The totally reflected light rays impinge upon a second face. A plurality of light-sensitive elements is provided for detecting the angular range .beta. covered by the beam after it has been totally reflected or coupled out, respectively. In order to enable the sensor to be adapted to a plurality of applications and in order to obtain reproducible, digitized output values, independently of any local disturbing factors or long-term phenomena, the body is designed as an elongated waveguide in which light rays are subjected to multiple total reflection. The light-sensitive elements are arranged at an axial distance h from a waveguide face.

Abstract: A method and apparatus are disclosed for monitoring the contents of a container in order to detect when the contents are below a predetermined level. An optical metering signal from a light source driven by a multivibrator is projected at a predetermined level across the space within the container. A light sensor on the opposite side of the space within the container detects incident illumination there. The metering signal is incident there only when the contents of the container are below the predetermined level. Otherwise, the contents either block or refract the metering signal from its normal path, and the metering signal goes undetected. A unity gain amplifier of variable sign coupled to the light sensor and to the multivibrator determines when signal from the light sensor are synchronized with the output of the multivibrator, so as to be deemed to correspond to pulses of the metering signal.

Abstract: An apparatus is used for sensing liquid level in a vessel at multiple levels and with variable resolution using optical properties. Known electrical optical sensing devices are not adequate for applications where multiple level, fine or variable resolution sensing are desired. The subject liquid level sensor includes a mounting apparatus adapted for insertion into the vessel, for containing the electric circuit, and for filtering the liquid entering the sensor. In addition, the sensor includes an array of sensing elements electrically connected in parallel and attached along the mounting apparatus spaced from one another at preselected locations. The sensing elements are adapted to deliver a plurality of electric signals in response to the absence of liquid at the level of the respective sensing element. The electric signals are then summed by an amplifier, which then delivers a resultant liquid level signal.

Abstract: An optical probe is sealingly mounted in an access port of a pressurized container. The probe comprises a glass rod of a predetermined thickness having a conical end tip. An optical transmitter and receiver is connected to the glass rod. The fiber optic transmitter and receiver sends visible red light down the glass rod. When the liquid level inside the container drops below the end tip of the glass rod, reflected light will be received from the glass rod and detected.

Abstract: A liquid detector utilizing fiber optics, by which the presence of oils and various solvents can be detected. The detector is internally safe because the optical fiber is an insulator and may therefore be used to monitor liquids involving fire or explosive hazards. The detector may be used to detect leakage when storing oils and solvents, because it reacts most rapidly with these liquids. The detector makes use of capillarity of a sensing pick-up thereof, the optical reflection coefficient of the pick-up material changing as the pick-up material comes into contact with the liquid to be detected.

Abstract: A fluid level sensor is provided in a fluid dispensing system, primarily in a photoresist dispensing system used in a semiconductor manufacturing process. A bubble is introduced into the fluid shortly before fluid supply is emptied, said bubble being used to detect a low fluid level. The invention uses a snap-on combination cap and pickup tube, the pickup tube having a small hole near its lower tip, and the cap containing an optical bubble detector.

Abstract: A liquid level sensor comprises a probe containing closely spaced therein an elongate light emitter and an elongate light collector, the housing of the probe permitting light to issue from the interior from the emitter and to return to the collector. A light transmitting medium fills the probe housing. Means are provided for feeding light to the emitter and from the collector. An indicator can be provided, adapted to provide a level indication obtained form the light fed from the collector.

Abstract: A fluid indicator for use in a containment vessel. A sensor body is movable by a drive relative to the vessel. An indicator automatically indicates the location of the sensor body relative to the vessel. A passage is in the body through which fluid from the vessel can be viewed and a light emitter is positioned in the body so as to direct a beam through the fluid. A light sensor also positioned in the body receives light after it passes through the fluid and produces a signal in response thereto.

Abstract: An optical sensor element provides cantilevered support of a bent length of glass-rod core of first refractive index having a cladding of second refractive index that is less than the refractive index of the core, and wherein the outer radius of the bend (which may be a single bend, or a plurality of spaced bends) is at least the diameter of the cladded core. Provision is made at the respective ends of the cladded core for completing a light circuit via the length of the cladded core, and flexible leads, as of multi-mode optical fiber, enable completion of the optical circuit to a remotely located control unit having an electrically powered light source and a photodetector, at the respective ends of the circuit.

Abstract: The present invention is related to a sight glass(10) that utilizes both reflected light at a glass to air interface(40) as well as the light transmitted through a glass to fluid to glass interface(44) to form a light pattern that is indicative of the true fluid level. By requiring that light always appear in either an "air" or "fluid" channel(42,46), any absence of light is assumed due to film coated surfaces or to other abnormal conditions. An absence of light is a signal that maintenance is required.

Abstract: An apparatus for detecting volumetric leaks includes an arrangement for measuring linear displacement of a surface, including the surface of a liquid. The arrangement includes a beam generator for directing a collimated or coherent beam of energy onto a surface, a non-planar mirror to receive the beam as it reflects from the surface, and a receptor for receiving the beam as it is reflected from the mirror. Changes in position of a footprint of the beam on the receptor correlate to changes in displacement of the surface and accordingly, volumetric changes of a contained liquid. The non-planar mirror amplifies or exaggerates the changes in the position of the footprint relative to linear displacement of the surface so as to enable detection of small displacements of the surface.

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: A system and sensor for remotely monitoring the state of the condition of the electrolyte within each of the battery cells of a power supply is disclosed. The system includes a sensor having a dual ball-float and track arrangement for shuttering a pair of light sources and so as to independently detect and differentiate predetermined low electrolyte specific gravity and a low level of the electrolyte. Two multiplexing units receive the sensor signals and display separate indications of each battery and the states detected. The detector uses a gravity responsive ball disposed within a track that shutters one light source at a predetermined low specific gravity and a second level responsible ball within a second track located above the gravity track and ball. The level ball has a specific gravity which is less than that of the specific gravity responsive ball and shutters the second light source at a predetermined low electrolyte level independently of changes in the specific gravity of the electrolyte.

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: 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: This invention relates to a bi-color fluviograph of transmission and reflection type, which increases the intensity of the red and green lights. Colored light sources are used and the principles of transmission and reflection of prism are adopted to transmit or reflect red and green light respectively. When there is some water in it, red color can be seen clearly. When there is no water, green color can be seen clearly. This new fluviograph improves the utilizing condition of the former bi-color fluviograph of transmission and reflection type. It can reduce the frequency of cleaning the steam boiler fluviograph which has no water treatment equipment and it can also used for pressure containers with poisonous and combustible.

Abstract: A device for detecting the liquid level in a tank. The device inlcudes a dioptric element having faces and a base immersible in the liquid. A bundle of optical fibers is operationally arranged with the dioptric element so that the dioptric element is disposed at one plane end of the optical fiber bundle while the other plane end of the optical fiber bundle provides an observation face. The bundle of optical fibers and the dioptric element are arranged and adapted to provide two separate and distinct zones in the observation face which are directly viewable in the surface of the observation face. One zone provides a signal zone which receives a larger quantity of light from a dioptric element when the element is not immersed than when it is immersed. The other zone provides a reference zone which receives a constant quantity of light from the dioptric element whether or not the dioptric element is immersed in the liquid.

Abstract: A monitor and filler assembly providing an easily observable reading as to the fluid level in a reservoir such as an automatic transmission or crankcase of an automobile. The filler may be integrally formed with the monitor to allow for easy replenishing of the reservoir fluid to ensure proper operation of the automobile.

Abstract: A pressure vessel comprises an enclosure in which are a liquid orifice and a gas orifice spaced from the liquid orifice. A separator divides the enclosure into two variable volume chambers. One of these is a liquid chamber communicating with the liquid orifice and the other is a gas chamber communicating with the gas orifice. The separator has a transverse wall spaced from the gas and liquid orifices and movable inside the enclosure. There is an orifice in the enclosure communicating with the gas chamber through which there is passed into the gas chamber a sensor which is responsive at one end to the presence of a liquid. In a neutral position of this transverse wall the responsive end of the sensor is nearer the transverse wall than it is to the orifice in the enclosure through which it passes into the gas chamber. The sensor preferably comprises an optical probe.

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 photoelectric buffle detector apparatus (20) including a container (22) containing a liquid (24) having a top surface with a top side and an under side. A light emitting source (60) is positioned for emitting light toward the top surface (42) of the liquid (24). A light detecting source (70) positioned for detecting light emitted from the light emitting source (60) and reflected from the top surface (42) of the liquid (24). The light detecting source (70) outputs a signal indicating the presence of a wave pattern at the top surface (42) of the liquid (24) caused by gas bubbles rising to the top surface (42) of the liquid (24).

Abstract: Method for the treatment of fluidized carbon black with gases in a fluidized bed, wherein the carbon black and the treatment gases are conveyed for introduction in an unique operating procedure into the treating region in a countercurrent stream manner. The mass streams of the carbon black and the treating gases are held constant and the mass streams of the starting carbon black or the treated carbon black is regulated with the help of an optical electrical level sensor so that the height of the fluidized bed is held on a predetermined level. An apparatus is shown for the carrying out of the fluidized bed countercurrent process which has a novel carbon black product delivery system and is provided with a optical electrical level sensor means for controlling the level of the fluidized bed. The sensor comprises a hair pin shaped lighting circuit composed of two legs or rods separated by a gap.

Abstract: Several specific types of optical sensors capable of measuring temperature, pressure, force, acceleration, radiation and electrical fields, fluid level, vapor pressure, and the like, are disclosed, along with an electro-optical system for detecting the optical signal developed by the sensor. One such probe utilizes a convex shaped structure consisting of an elastomeric material attached to an end of an optical fiber, the elastomeric material being coated with a luminescent material, a combination that is capable of measuring both temperature and pressure. Such a probe is also specifically adapted for measuring surface temperature by making a good physical contact with the surface being measured. Another such probe utilizes a similar structure but of a non-elastomeric material for the purpose of detecting both temperature and either index of refraction of vapor pressure changes.

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 method and apparatus for substantially eliminating measuring inaccuracies in a storage tank leak detection system caused by temperature-induced volumetric changes in the stored fluid product is described. In a preferred embodiment of the method, a limp bladder is connected to an end of a pressure tube having an inlet and a substantially hollow core. The pressure tube and the bladder are filled with a medium having a temperature coefficient substantially lower than the temperature coefficient of the fluid product. The pressure tube and the bladder are then supported in a substantially vertical manner in the storage tank such that a first portion of the medium is supported in the bladder in static equilibrium with respect to a second portion of the medium supported in the pressure tube. The large disparity between the temperature coefficients of the medium and the fluid product insures that temperature-induced volumetric changes in the fluid product do not vary the level of the medium in the pressure tube.

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 drink dispenser assembly used for filling receptacles when placed into a position to receive liquid dispensed from a nozzle comprises a valve which is controlled by a solenoid connected to an electric circuit, a switch operated at the will of the operator to actuate the electric circuit and the solenoid to open the valve and initiate a filling cycle, an assembly operative to suspend the receptacle below the nozzle, and an arm positioned proximate the receptacle when the receptacle is placed into a position to receive liquid, the arm operative to sense the filled condition of the receptacle and deactuate the electric circuit and the solenoid to close the valve and terminate the filling cycle.

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: 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: 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: An optical adapter for a light-wave rangefinder comprising a light emitting means for emitting a distance measuring light wave modulated by a predetermined modulation frequency, and a light receiving means for receiving a reflecting light wave reflecting from a target point to which the distance measuring light wave is directed, wherein a time delay between the distance measuring light wave and the reflecting light wave is utilized to determine the distance to the target point, the optical adapter comprising at least one photoconduction means for conducting distance measuring light wave and the reflecting light wave, and at least one single objective optical means for projecting the distance measuring light wave from the photoconduction means towards the target point, for condensing the reflecting light wave reflecting form the target point and for guiding the light wave to the photoconduction means.

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: 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.