Abstract: A liquid content detecting device is provided which can detect the contents of liquid components such as alcohol in a mixed fuel (both regular and premium gasolines) with a high degree of preciseness at all times over the entire operating temperature range in which the device is used. A refractive index sensor senses the refractive index of a liquid mixture which includes N kinds of liquid components. A liquid-kine identifying means identifies the kind of each of the liquid components. A temperature sensor senses the temperature of the liquid mixture. A liquid content calculator stores a temperature-dependent refractive index characteristic of various kinds of liquids including the liquid components in advance.

Abstract: This invention relates to a device and a method for measuring the specific gravity of liquids, in particular, urine. This invention more particularly concerns a component of an automated system for urinalysis, either of humans or animals. The device may also be developed as a stand-alone unit and includes a dispenser, a sample container in which the liquid is dispensed and flushed, and a fiber optic sensor system to record the refractive index of the liquid. The invention is particularly suited for use with small clinical samples.

Abstract: Apparatus and methods for determining the composition of a fuel mixture comprising hydrocarbons and oxygenates, wherein more than one measurement is made of the interaction of light passing through a light guide and the fuel mixture in which the light guide is immersed using light of a variety of different wavelengths and/or light guides having different indices of refraction. Data from the measurements is then interpreted to establish the concentration of hydrocarbons in the fuel mixture and/or the concentration and identity of the oxygenates. Pursuant to one type of embodiment of the invention, a plurality of light guides is provided, with particular light guides being used for each oxygenate to be analyzed (including water). In accordance with an alternative type of embodiment of the invention, a single light guide is employed with a single wide band light source and a plurality of light sensors.

Abstract: A device for measuring entrained air in concrete, includes a needle tube for insertion into the concrete, the needle tube having a distal end; an optical fiber extending through the needle tube to the distal end, with the end of the optical fiber and the distal end of the needle tube being ground to have a sharp conical angle; a laser diode which produces laser light; a coupling device which supplied the laser light from the laser diode to the optical fiber and which separates the light reflected back through the optical fiber; and a photodetector which converts the received light from the coupling device to an electrical signal corresponding to the intensity of the reflected light.

Abstract: An index of refraction sensor having a photo detector array with variable sized elements is provided. The photo diode array comprises a plurality of diodes with varying area. The diodes farthest from a light emitting diode having a larger area than those closer to the light emitting diode. Preferably the diode area is designed so that each of the diodes produces approximately the same current output when exposed to light from the LED. Each diode in the photo diode array is sequentially powered and the photo diode outputs are summed together. A power input from a first diode in the array is coupled to a start input of a time measurement circuit. The summed output of the photo diode array is coupled to a stop input of the time measurement circuit. Elapsed time measured by the time measurement circuit is thus a function of reflected light edge location, and therefore a function of index of refraction of the fuel mixture.

Abstract: Method of ATR spectroscopy and substrate probe for use therein. The probe mprises a single optical fiber sensor, or a bundle of such sensors, with the sensing zone of each sensor comprising two unclad frustoconical portions merging at their frustrums.

Abstract: In order to measure the refractive index of a fluid use is made of a rod (1) which projects into the fluid and has a refractive index which is slightly larger than that of the fluid. At the end which is not immersed in the fluid, the rod is provided with a light source (3) radiating into the rod and with a light detector (5). That part of the rod which is to be immersed in the fluid is partially surrounded by a casing which permits only total reflection of the light, while at the site of the part or parts of the rod not surrounded by the casing refracted light can, depending on the refractive index of the fluid, leak into the fluid. A casing which is stable against the corrosive action of an aggressive fluid, such as concentrated sulphuric acid in a battery, consists, according to the invention, of a layer (10), trapped in a transparent tube (8), of a medium which has a lower refractive index than the said rod, in particular gas or vacuum.

Abstract: An ATR sample cell is disclosed, of the type incorporating a circular internal reflectance crystal. A flowing liquid sample has input and output ports in the IRE housing, or cell, which are offset from the axis of the circular IRE (or rod) sufficiently to direct the flow of liquid against the internal wall (usually stainless steel) of the flow jacket, rather than against the IRE. This tends to create a helical flow path from the input port at one end of the housing to the output port at the other end of the housing. In order to further control the sample flow path, and augment the spiraling effect, two further improvements are disclosed. The structure through which the sample material enters the sample chamber surrounding the IRE is designed to establish a spiraling motion of the liquid flow before it enters the sample chamber. Also, the inner cylindrical wall of the metal housing has a groove which forms a helical path from the input to the output end.

Abstract: A mixing ratio detecting device for composite liquid has a transparent column placed so that a bottom of the column is in contact with a mixing liquid, and a light emitting diode disposed so that light beams therefrom are incident on one side of the column to pass therethrough so as to impinge on an interface between the bottom of the column and the mixing liquid. The light beams impinged on the interface less than a critical angle are refracted, while the light beams impinged on the interface more than the critical angle totally reflected to escape from other side of the column. A photo diode is provided to receive the light beams escaped from the other side of the column so as to generate an output. An effective photo-receiving area of the photo diode is in the form of an inversed trapezoid to compensate for characteristics of the output from the photo diode.

Abstract: A refractive index FOCS has a fiber optic core with a partly light transmissive thin metal film clad of an effective thickness and light transmissivity so that transmission through the core is strongly affected by the refractive index of a surrounding liquid or vapor medium. The metal clad and surrounding medium produce a localized refractive index at the core interface which modulates light transmission through the core as a function of the medium refractive index. The clad is made of platinum, or also of gold, rhodium, palladium, nickel, iron, cobalt, ruthenium, iridium, osmium, zinc, copper, silver, chronium, molybdenum, tungsten, vanadium, niobium, tantalum, titanium, zirconium or hafnium. The clad is also made of oxides of these metals, or metal compounds or alloys. With a fluorescent tip, the changes in the fluorescent signal are a measure of the medium refractive index. With a reflective tip, the changes in the reflected signal are measured.

Abstract: The index of refraction of a liquid is measured using an optical fiber rectometer having a light transmitting optical fiber by immersing a portion of the optical fiber in the liquid and launching light into one end of the optical fiber at a selected non-zero launch angle with respect to the fiber axis. Light transmitted through the optical fiber is detected at the other end of the optical fiber and a determination is made of the index of refraction of the liquid in accordance with the detected light and the selected non-zero launch angle. By varying the launching angles of the light the range of the refractometer is increased. The light transmitting optical fiber is provided with a region having at least one tapered portion for further increasing the range of the refractometer. The tapered portion of the optical fiber is disposed between a refractive end of the optical fiber and the light source for providing single-ended operation.

Abstract: The invention is directed to a method for determining the refractive index (n) of a substance wherein monochromatic light is conducted to a single-mode wave guide integrated into a substrate. The wave guide is brought into contact with the substance to be measured along a segment of predetermined length. In this way, the effective refractive index in this segment of the wave guide is changed. This effect is utilized for measuring the refractive index of the measured substance. The change of the effective refractive index causes a phase displacement of the light travelling through this measuring segment. This phase displacement is measured as a phase difference to a light component not influenced by the measuring substance. This measurement is preferably made interferometrically.

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: The discriminating device comprises an optical coupler (4) having at least three ends (5 to 8) to which are connected a semiconductor source of light (1) whose intensity is modulated, a semiconductor photoconductor (2) and an optical probe constituted by a multi-mode optical fibre (3) whose end has a pointed shape. This discriminating device is in particular applicable in a device for measuring the voluminal fraction of at least one fluid of a current of non-mixible fluids.

Abstract: Reference materials of differing indices of refraction or acoustic impedances are incorporated into liquid compositions to monitor the solidification process of these liquid compositions. Light or acoustic waves are used to indirectly measure the difference between the index of refraction or acoustic impedance of the solidifying composition and the reference material. The method provides an accurate in situ indication of the completion of the solidification process as well as a monitor of the degree of solidifications during the solidification process.

Abstract: An apparatus for measuring the refractive index of liquid particularly suitable for use in an ink-jet printing system is provided. The apparatus includes a light emitting diode and a photodiode which are optically coupled by an optical fiber which in turn is partly immersed in a liquid to be measured. In one aspect, the wavelength of light emitted from the light emitting diode is so set to be outside a light absorption wavelength range of the liquid to be measured. In another aspect, provision is made of a temperature dependent resistor which changes its electrical resistance depending on the temperature of the liquid to be measured so as to vary the level of the driving current to be applied to the light emitting diode thereby varying the amount of light to be emitted.

Abstract: A system for detecting chemical characteristics within a material includes an optical fiber having a relatively short unclad sensor section for embedding in a material, a source of infrared radiation to direct infrared radiation into the fiber, and an optical decoder connected to the fiber to detect the spectrum of infrared radiation absorbed by the material in which the sensor section is embedded.

Abstract: A sensor for mixing ratio of liquid fuel comprising: a cylindrical enclosure having both inlet and outlet opening to act as a passage through which a mixing liquid fuel flows; a transparent column concentrically disposed into the enclosure to make outer surface contact with the liquid fuel; light emitting diode and photo diode each provided so as to sandwich the column in the lengthwise direction, so that the light emitted from the former enters the column through its one end and reflects at the boundary of the column and the liquid fuel, and go out of the other end thereof to fall on the latter; a temperature compensation photo diode disposed in the enclosure with the light of the light emitting diode partly as a light source to rectify the characteristics influenced under the ambient temperature variation; a voltage control circuit provided to control the voltage across the light emitting diode so as to maintain uniform output from the temperature compensation photo diode.

Abstract: There is provided an apparatus for measuring the refractive index of fluids. The apparatus comprises a substantially U-shaped sensor rod made of a transparent material and is submersible in the fluid. The bent portion of the sensor rod has a diameter of curvature at least two times larger than the diameter of the sensor rod, and chosen so as to optimize sensitivity for a given range of indices. The two ends of the U-shaped sensor rod are connectable to a housing and a light source inside the housing has optical access to the face of one of the sensor-rod ends. A light detector means also disposed inside the housing has optical access to the face of the other one of the sensor rod ends.

Abstract: Waveguide apparatus for use in substance analysis has a waveguide, with a surface area in contact with the substance, for transmitting electromagnetic radiation along the axis of the waveguide whereby propagation characteristics of the radiation are altered in accordance with properties of the substance adjacent the waveguide. A waveguide entrance prism is positioned at the radiation entrance end of the waveguide, for guiding radiation into the waveguide. The prism has a first face arranged at an angle with the waveguide axis to cause radiation entering the prism to propagate along the waveguide. In one embodiment, a longitudinal partition is arranged adjacent the waveguide substantially parallel to the waveguide axis, for partitioning the waveguide surface area into at least two parts so that multi-substance analysis can be carried out.

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: Method and apparatus are disclosed for determining one or more physical characteristics of individual bubbles in a gas-liquid system and a gas-liquid-solid system at high temperatures and pressures. An in situ probe device is inserted into the system over which individual bubbles flow. The probe device has a plurality of independent probes. Each has a rounded fibre optic end portion projecting into the system. A source of incident light is directed onto each of the probes. The rounded end portion of each probe is formed with a radius of curvature sufficiently large whereby the angle of incidence of the source light at the rounded portion is greater than the angle of total reflection for the fibre optic when in contact with the gas. The angle of incidence is less than the angle of total reflection for the fibre optic when in contact with the liquid. The plurality of probes are spatially arranged to detect one or more of the bubble physical characteristics as a bubble flows over the probe device.

Abstract: A refractometer comprises a light source, an angle prism and an optical system in a casing so mounted that the optical system focuses an image of a diaphragm at said light source upon a double photodiode located beyond the prism and supported by an oblique surface of the casing. The ratio of the output of one photodiode to the output of the double photodiode is measured to register the index of refraction.

Abstract: A fiberoptic probe for in situ sensing of liquid level, concentration and/or phase change contains the optical and electrical components as well as a reference fluid so that the components are at the temperature of the fluid to be monitored. A reference fiber is located in the reference fluid which is sealed in the probe so that volatile reference fluids can be used.

Abstract: A refractometer for measuring the index of refraction of a sample medium comprises a sample medium sensor and a reference medium sensor. Both sensors are combined into a single measuring probe which is connected by a flexible cable to a housing unit which accommodates the source of light, photodetectors, the test data processor and the indicator. The refractometer with the single probe is portable and easy to handle.

Abstract: A generated signal is passed through an elongated signal conveying element positioned preferably perpendicular to the surface of a fluid the level of which is to be measured. The signal is directed from the signal conveying element to a detector element which senses the signal output from the signal conveying element. The signal output detected in an optical embodiment varies logarithmically with the depth of immersion of the signal conveying element into the fluid. A preferred embodiment employs an electromagnetic wave, e.g., light, signal which passes through a light pipe signal conveying element. By nearly matching the light pipe index of refraction with that of the fluid, a predetermined percentage of the wave is lost into the fluid each time the light is reflected further along the pipe.

Abstract: A fuel supply system for fuels, among which hydrocarbons, such as gasoline, alcohols or other fuel, or a mixture thereof, for combustion engines, provided with a device to determine the instantaneous state or composition of the fuel and to emit a signal as a variable for the control of the dosage device of the air-fuel ratio, comprising an opto-electronic sensor mounted in the fuel to measure its index of light refraction, and an electronic circuit connected to the sensor to control the dosage device in accordance with the determined state or composition.

Abstract: An apparatus or device for determining the index of refraction of a fluid referred to or reduced to a predetermined reference temperature comprises a light source, light detector and means forming a bent light-conducting path between the source and the detector such that the intensity of the detected illumination represents the refractive index of the fluid surrounding the light-conductive path. According to the invention, the light source comprises an electroluminescent diode, e.g. a light-emitting diode of the LED type which has a temperature coefficient in conjunction with the temperature coefficient of the optical fiber which compensates substantially precisely for veriations in the temperature coefficient of the effective index and the fluid with which both the path and the LED are in thermally conducting relation, e.g. in direct contact.

Abstract: The device comprises two optical probes (51 and 52) consisting of a light conducting body which are designed to be immersed in the liquid by an intermediate section (53, 54) of the body, two light sources (60, 70) illuminating an extremity respectively of one (58) and of the other (68) body of the probes, two photoelectric transducers (61 and 72) located at the other extremity respectively of the first (58) and of the second (68) body of the probes, a member (73) which divides the signals originating from these transistors and a member (74) for the display of the resulting signal originating from that divider member.

Abstract: A fluid flowmeter of the vortex shedding type. The vortex frequency is determined from variations in the internal reflectivity of a prism 16 mounted in the fluid and coupled to a light source 13 and to a detector/frequency meter 14 via an optical waveguide arrangement 15. Passage of a vortex adjacent the prism 16 causes a temporary change in the local fluid refractive index and hence a change in the intensity of light internally reflected by the prism.

Abstract: An immersion-type refractometric device for measuring the concentration of solutions including a probe having a curved measuring surface on the immersible tip. A light source directs a diverging light beam internally through the probe body toward the measuring surface. In one embodiment, light reflected from the measuring surface is received by a light-reflecting surface on the probe tip and directed through the probe body toward a photosensitive element connected to a measuring circuit which provides an output signal indicative of solution concentration. In another embodiment, the photosensitive element is located in the probe tip and receives reflected light directly from the measuring surface.

Abstract: A device for detecting the presence of contaminating water in a fuel tank as well as for measuring the density of the fuel in the tank which includes an elongated body of optical material arranged to be mounted in a fuel tank in a vertically extending position, one side face of the body forming an interface with the fluid in the tank, and a plurality of light sensors on the opposite face of the body arranged in spaced-apart relationship, together with light-emitting means at the bottom of the body which emit a divergent group of rays of successively increasing angles of incidence upwardly so that those rays exceeding the critical angle at the interface for a fuel of a specific index of refraction are reflected to illuminate those sensors corresponding to the rays exceeding the critical angle to thereby provide a detected output representing the density of the fluid, the light-emitting means providing a second group of rays striking the lower portion of the interface which are reflected when water is present t

Abstract: A device for producing a light signal corresponding to the refractive index of a fluid medium comprises an elongated light-conducting body consisting of an input section and an output section connected to each other by an intermediate curved section adapted for immersion in said fluid. This curved section is provided with a plurality of curvatures arranged successively and bent alternately in opposite directions, whereby light passing by refraction into said fluid undergoes a notably greater variation, as a function of the refractive index of said fluid medium, than can be obtained with a curved section bent in a simple direction. A light signal is thus provided with a high sensitivity. The complex-curved, preferably .OMEGA.-shaped, section can be enclosed in an envelope composed in part of filter material.

Abstract: A radiation carrier such as an optical glass fiber is embedded in a body of material such as a laminated composite panel with the free ends of the fiber extending to or beyond the edges of the structure so that radiation such as light can be directed through one end of the carrier and measured at the other end thereof, to monitor and detect the presence of moisture in the interior of the structure.

Abstract: A device for producing a light signal corresponding to the refractive index of a fluid medium comprises an elongated light-conducting body consisting of an input section and an an output section connected to each other by an intermediate curved section adapted for immersion in said fluid. This curved section is provided with a plurality of curvatures arranged successively and bent alternately in opposite directions, whereby light passing by refraction into said fluid undergoes a notably greater variation, as a function of the refractive index of said fluid medium, than can be obtained with a curved section bent in a simple direction. A light signal is thus provided with a high sensitivity.

Abstract: A refractive index detector is described comprising a waveguide, means for contacting said waveguide with a fluid, a light source and means to transmit light into said waveguide, means for detecting light exiting from said waveguide as an indication of the refractive index of said fluid and means to automatically change the angle of incidence of the light entering said waveguide in response to changes of refractive index of said fluid. A preferred embodiment of the detector for use as a detector for gradient elution chromatography has means to indicate the rate of change of refractive index. A preferred means to automatically change the angle of incidence of the light entering the waveguide is a movable prism. It is preferred to use a monochromatic light source in the detector. It is preferred to provide reference means for the detector to compensate for changes in intensity of the light output from said light source.

Abstract: An apparatus for continuous measurement of the density of a liquid within prespecified limits, by utilization of the law of refraction,particularly for the continuous measurement of acid density of a storage battery of a motor vehicle for the purpose of determining the state of charge of the battery.The apparatus is equipped with a photoconductive rod, a light source which radiates a pencil of parallel or nearly parallel rays into the rod toward a measuring surface, located at the end of the rod immersed in the liquid. The surface is struck by the pencil of rays at an angle with respect to the surface that equals at most the total reflection angle occurring at the lower limit of liquid density. A photosensitive element is located in the path of the ray pencil opposite a surface deflecting the pencil of rays, which is refracted by the measuring surface into the liquid.

Abstract: A process for infrared spectroscopic monitoring of insitu compositional changes in a polymeric material comprises the steps of providing an elongated infrared radiation transmitting fiber that has a transmission portion and a sensor portion, embedding the sensor portion in the polymeric material to be monitored, subjecting the polymeric material to a processing sequence, applying a beam of infrared radiation to the fiber for transmission through the transmitting portion to the sensor portion for modification as a function of properties of the polymeric material, monitoring the modified infrared radiation spectra as the polymeric material is being subjected to the processing sequence to obtain kinetic data on changes in the polymeric material during the processing sequence, and adjusting the processing sequence as a function of the kinetic data provided by the modified infrared radiation spectra information.