Abstract: An optical oil component sensor and a sensing method using the sensor, which can identify similar fuel oil in real time. The optical oil component sensor includes a light source unit, a reference optical waveguide, configured to guide light thereinto, for receiving and outputting light emitted from the light source unit, a sensing optical waveguide, configured to guide light thereinto, for receiving and outputting light emitted from the light source unit, wherein a portion of the sensing optical waveguide is formed to be in contact with test target oil, a light-receiving unit for receiving both a reference light signal, output from the reference optical waveguide, and a test light signal, output from the sensing optical waveguide, and a control unit for identifying components of the test target oil by comparing optical properties of the reference light signal and the test light signal with each other.

Abstract: An apparatus for measuring a length of an optical resonant cavity includes a frequency tunable light source, a beam splitter, a frequency modulator and an optical resonant cavity. The frequency tunable light source emits a beam. The beam splitter is disposed on the optical path of the beam for dividing the beam into a first beam and a second beam. The frequency of the second beam is modulated by the frequency modulator to differ from the frequency of the first beam by a beat frequency. The optical resonant cavity is disposed on the main optical path of the first beam and the main optical path of the modulated second beam. The first beam and the modulated second beam enter the optical resonant cavity for measuring a length of the optical resonant cavity, and a variation in cavity length is calculated from the beat frequency.

Abstract: There is described a fiber-optic sensor for measuring a light signal from a fluorescible sample comprising heavy metal ions, for example. The fiber-optic sensor comprises an optical fiber having a side surface by which the light signal from the fluorescible sample is inputted. The optical fiber is corrugated to form at least two gratings on the side surface of the optical fiber. Each grating comprises periodically longitudinally spaced-apart valleys on the surface of the optical fiber, and is longitudinally spaced apart from any other grating of the at least two gratings.

Abstract: A method for forming a multilayer structure comprises the steps of: depositing a first polymerizable layer on a substrate; applying microwave energy to the polymerizable layer while monitoring at least one property of the layer; and, ending the application of microwave energy when the monitored property indicates that the polymerizable layer has reached a desired degree of cure. The property monitored may be optical, e.g., Raman spectrum, or electrical, e.g., dielectric loss. This process control strategy lowers the overall thermal budget, and is especially suitable for curing polymer films on silicon. The method may be used repetitively to cure multiple layers of polymeric material when a thicker film is needed.

Abstract: The invention relates to a method for optimizing the operation of a thermal engine having combustion parameters controlled by an electronic housing and at least one engine mapping, characterized in that the method comprises: a step of carrying out a near-infrared spectroscopic analysis of a bio-fuel containing a mixture of alcohols and/or ethers and/or water in order to determine the proportions of water and of at least one other oxygenated compound of the alcohol and/or ether type contained in the bio-fuel; and a step of selecting and/or modifying said mapping on the basis of the analysis result in order to optimize the operation of the thermal engine.

Abstract: A gas detector system includes a transmitter (1), which has a light source (3), which emits an analytical light beam (5). A transmitter lens assembly (7), to focus the analytical light beam (5) in an emission direction (9), includes a receiver (19, 19?) with a receiver lens assembly (21), defining a receiver focal point (27, 27?) and a receiver axis (23). A light mixing rod (29) defines a first rod axis (35) that extends from an inlet end (31), pointing toward the receiver lens assembly (21), to an outlet end (33) facing an analytical detector (39) and a reference detector (45). An analytical filter (43, 43?) is arranged in front of the analytical detector (39) as viewed from the receiver lens assembly (21). A reference filter (49, 49?) is arranged in front of the reference detector (45) as viewed from the receiver lens assembly (21).

Abstract: Reference cell (8) for use with a fiber optic probe (1) comprising a base wall (11), upstanding walls (12) each having an optical window (13, 15), and a top wall (14) having a further optical window (16) adapted to allow light to pass to and from a fiber optic probe. The base wall (11) comprises a reflector (19) which reflects incident light from the fiber optic probe back to said probe (1). The top wall (14) has an attachment for receiving an emitting and a receiving end of a fiber optic probe (1). The cell (8) allows use of standard fiber optic probe (1) with other optical equipment when the path length and the probe optical characteristics require validation to international standards. The calibration of the probe (1) is analogous to calibration of laboratory spectrophotometers and can therefore be validated. The device (8) enables probes (1) to be used for applications where precision and accuracy are essential.

Abstract: A degree of cure measuring apparatus has: a second optical fiber for emitting light from a tip face thereof; a probe for holding adhesive agent and irradiating the adhesive agent with light while the adhesive agent is in contact with the tip face of the second optical fiber; a detector for detecting light that is reflected from an interface between the tip face of the second optical fiber and the adhesive agent and then returns to the second optical fiber; and a computer for calculating the refractive index of the adhesive agent from the rate of the light amount of the light detected by the detector to the emission light amount from the tip face of the second optical fiber.

Abstract: A portable liquid design system includes a portable information handling system (IHS) that employs a liquid design application capable of operating in different modes to design different liquids such as corn syrup, espresso, coffee, soda pop and others. The portable liquid design system may include a refractometer to measure the refractive index and temperature of a liquid under test. The liquid design application may apply the measured refractive index and temperature to a 3 dimensional representation of the correlation of refractive index, temperature and concentration (% total dissolved solids) to determine a particular concentration corresponding to the measured refractive index and temperature. A single 3 dimensional scale may apply to virtually all values of interest of refractive index, temperature and concentration for a particular liquid under test.

Abstract: Refractive index tools and method. A refractive index tool includes a wave source configured to generate a wave; a transparent rod configured to receive the wave from the wave source; and a wave detector configured to receive the wave from the transparent rod. The wave source is provided at a first end of the transparent rod and the wave detector is provided at the first end or a second end of the transparent rod so that the wave emitted by the wave source travels through the transparent rod and experiences total internal refraction prior to arriving at the wave detector.

Abstract: Refractive index tools and method. A refractive index tool includes a wave source configured to generate a wave; a transparent rod configured to receive the wave from the wave source; and a wave detector configured to receive the wave from the transparent rod. The wave source is provided at a first end of the transparent rod and the wave detector is provided at the first end or a second end of the transparent rod so that the wave emitted by the wave source travels through the transparent rod and experiences total internal refraction prior to arriving at the wave detector.

Abstract: Method and system for identification of a changed state of a fluid with respect to a reference state of the same fluid, the fluid having an optical parameter changing with the change of the state of the fluid. The method comprises: a) providing an optical arrangement including a transparent enclosure with a portion of the fluid, and an object observable through the optical arrangement, the arrangement being designed such that an image of the object in the changed state of the fluid is optically distinctive from an image of the object in the reference state of the fluid due to change of the optical parameter, at least one of the images being predetermined; b) illuminating the object with diffuse light; c) observing a current image of the object though the optical arrangement along an optical axis; and d) comparing the current image to the predetermined image to identify the changed state of the fluid. The comparison and the identification may be performed by eye or by a sensor with a logical circuit.

Abstract: An image rendering method for a computer system includes identifying a point in space to be illuminated from at least one line light for the point, and determining an illumination direction of the line light. The method further includes generating a plane passing through the point, and projecting the line light onto the plane. The method further includes determining a brightness contribution for the point responsive to a function characterizing the brightness contribution.

Abstract: A downhole refractometer apparatus and method include a light source, an optical fiber that receives light emitted from the light source and a fluid cell that receives a downhole fluid. A metalloid interface member is disposed to provide an interface with the downhole fluid in the fluid cell, and a light detecting device detects a light reaction at the metalloid interface member, the downhole fluid property being estimable at least in part based on the light reaction.

Abstract: A downhole refractometer apparatus and method include a light source, an optical fiber that receives light emitted from the light source and a fluid cell that receives a downhole fluid. A metalloid interface member is disposed to provide an interface with the downhole fluid in the fluid cell, and a light detecting device detects a light reaction at the metalloid interface member, the downhole fluid property being estimable at least in part based on the light reaction.

Abstract: Fluid level detector device and method are disclosed, for determining the height level of one or more immiscible fluids in a vessel. The device includes at least one optical set-up including a light source for generating a beam of light of predetermined width and optical characteristics, the light beam arranged to be directed into the fluid so as to cause refraction of the light beam, dependent on the index of refraction of the fluid, the light beam covering a predetermined detection region. A photosensitive detector is provided capable of generating a signal corresponding to at least one optical characteristic of the light beam after passing the fluid. An interpreter is provided for receiving the signal, interpreting the signal and indicating the height level of the fluid.

Abstract: An optical biosensor using a surface plasmon resonance phenomenon includes an input optical waveguide including a first optical mode converting unit for converting a core mode to a cladding mode; and an optical sensing unit for allowing a specific wavelength among wavelengths constituting the converted cladding mode to be lost according to density of bio-material. The optical biosensor can accurately measure density of bio-material by using an optical signal.

Abstract: The invention relates to a refractometer and to a refractive index measuring method. The invention directs an incident light ray onto an interface of a medium of known refractive index and of the medium studied, then measuring the intensity of the reflected light ray. The ratio between the intensity of the incident ray and the intensity of the reflected ray allows the refractive index of the medium studied to be calculated by means of Fresnel's formulas.

Abstract: Disclosed herein is an apparatus and method for detecting a selected material that change an effective dielectric constant of a circular resonator. An example of the apparatus includes an input waveguide, an output waveguide and a circular resonator. The input waveguide receives electromagnetic wave from an electromagnetic wave source. The circular resonator is located adjacent to the input and output waveguides, which enables the resonator to receive electromagnetic wave from the input waveguide. The circular resonator bonds to a selected material, e.g. chemical gas, chemical liquid, and bio-agent. The selected material can change the effective dielectric constant of the circular resonator, which in turn causes a change in the electromagnetic wave intensity of the circular resonator. The output waveguide receives the change in electromagnetic wave intensity from the circular resonator, which can be used to determine the selected material qualitatively and quantitatively.

Abstract: The invention relates to a portable refractometer comprising a depression (7) for samples, located on an insertion tip (11) in such a way that once the insertion tip (11) has penetrated a liquid or a fruit, a sufficient quantity of the sample liquid remains in the depression (7) for samples, thus wetting a measuring surface (4) that is delimited in said depression by a transparent body. The refractive index of the wetting liquid can be determined by measuring the intensity of an optical beam that is reflected by the measuring surface (4).

Abstract: The invention relates to refractometry and attenuated reflectance spectrometry in a wellbore environment. Specifically, it pertains to a robust apparatus and method for measuring refractive index of fluids along a continuum (rather than in steps), and for measuring attenuated reflectance spectra, and for interpreting the measurements made with this apparatus to determine a variety of formation fluid parameters. The present invention provides a method and apparatus to distinguish between gas and liquid based on the much lower index of refraction of gas. It can also be used to monitor fluid sample clean up over time. The refractive index of a wellbore fluid is determined from the fraction, R, of light reflected off the interface between a transparent window that has a known refractive index and this fluid. Preferably, the refractive index is measured at some wavelength of light for which the fluid is not highly attenuating but is optimally attenuating.

Abstract: The invention relates to a refractometer and to a method of measuring the refractive index of a medium. An incident light ray is directed onto an interface consisting of a medium of known refractive index and of the medium being studied. Then the intensity of the reflected light ray is measured. The incident and reflected light rays are propagated in an optical fiber section. The ratio between the intensity of the incident ray and the intensity of the reflected ray allows the refractive index of the medium studied to be calculated by means of Fresnel's formulas.

Abstract: A fluid detector system for identifying a fluid or detecting presence of a substance in a fluid. The fluid detector includes at least two optical conductors, optical detectors coupled to outputs from the optical conductors; and a comparer for comparing the outputs from the detectors. Each optical conductor has an outer reflective surface. A first one of the optical conductors has a section with at least a portion of its outer reflective surface removed. The comparer can determine an optical refraction index of fluid at the section of the first optical conductor which has the portion of the outer reflective surface removed.

Abstract: The invention relates to refractometry and attenuated reflectance spectrometry in a wellbore environment. Specifically, it pertains to a robust apparatus and method for measuring refractive index of fluids along a continuum (rather than in steps), and for measuring attenuated reflectance spectra, and for interpreting the measurements made with this apparatus to determine a variety of formation fluid parameters. The present invention provides a method and apparatus to distinguish between gas and liquid based on the much lower index of refraction of gas. It can also be used to monitor fluid sample clean up over time. The refractive index of a wellbore fluid is determined from the fraction, R, of light reflected off the interface between a transparent window that has a known refractive index and this fluid. Preferably, the refractive index is measured at some wavelength of light for which the fluid is not highly attenuating.

Abstract: In order to measure the refractive index of a medium (18), for example a liquid or a gas, this system comprises a waveguide (14) having a blazed Bragg grating (16), the spectral response of which depends on the refractive index of the medium, a light source (20) in order to make this light interact with the grating, means (22) for the spectral analysis of the light which has interacted with the grating, means (24) for recovering the spectrum provided by the spectral analysis means and means (26) to correlate, from the recovered spectrum, the spectral response of the grating with one value of the refractive index of the medium.

Abstract: A refractometer which provides a “sugar” or “diet” indication when immersed on a beverage. The device is electronic and lights either a “sugar” or “diet” signal to the user. A prove has a light source and a photodetector at one end and an angled face at the other end. Depending on the refractive index of the beverage, the light is either reflected back into the probe and into the photodetector and exits out of the angled face and does not reflect back to the photodetector.

Abstract: A method and system for determining a spatially local index of refraction in optical materials is provided. Light, including a near-field intensity, is collected above a surface of the material. A probe is oscillated at a plurality of frequencies and in a substantially perpendicular manner relative to the surface of the material to detect the near-field intensity of the light. A distance of the probe from the surface of the material is modulated. Based on a ratio of the near-field intensity of the light detected at the plurality of frequencies, the local index of refraction is determined.

Abstract: An optical device for measuring a level of a fluid in a container wherein a light conducting body having a top surface and a bottom surface is positioned within the container and into the fluid. A first end of the light conducting body and an oppositely disposed second end, preferably having stepped end surfaces, reflect and refract light in a predetermined manner based upon the fluid level in the container. A resulting brightness of the top surface is therefore inversely proportional to the level of the fluid. Such an optical device is particularly suited toward application to a vehicle fuel tank.

Abstract: A device for use in an anaesthetic administration apparatus for identifying at least one liquid anaesthetic in the anaesthetic apparatus has a measuring unit for determining at least one parameter related to the refractive index of the liquid anaesthetic, a unit for determining the temperature of the liquid anaesthetic and an analysis unit for identifying the anaesthetic from the determined parameter.

Abstract: A sensor for measuring the change in refractive index of a liquid uses the lowest critical angle of a normal fiber optic to achieve sensitivity when the index of the liquid is significantly less than the index of the fiber core. Another embodiment uses a liquid filled core to ensure that its index is approximately the same as the liquid being measured.

Abstract: Devices for detecting hydration of cervical mucus (which is indicative of the course of a female's reproductive cycle) include a detector having a light source, a photoreceptor and a light guide positioned so as to guide light from the light source to the photoreceptor. The light guide includes at least one active surface to be wetted by the cervical mucus. The detector may be planar or curvelinear and may be embedded within a distal sensing head or extend upright therefrom (e.g., so as to somewhat penetrate the external cervical os during use). Most preferably, the light guide is fabricated from a fluorocarbon polymer. For use in vivo, the device will preferably include a proximal handle which allows the user to manipulate the distal sensing head into close proximity to the external cervical os. The handle may include a source of electrical power (e.g.

Abstract: A compact portable instrument for determining the percentage concentration of a material in a solution such as the amount of concentrate in an output from an Aqueous Film Forming Foam generator used to extinguish fires. The instrument comprises a refractive index sensor with a reflective type refractometer prism having a measuring surface in contact with liquids placed in a sample holder formed by an opening through a retainer plate. The measuring surface of the prism covers that opening and presses the retainer plate towards an outer surface of the instrument, that outer surface having entrance and exit ports for sample liquids at that opening. The refractometer senses the refractive index of liquid in the sample holder and, when properly calibrated, provides an output to a digital display that directly indicates the percentage concentration of material in the liquid.

Abstract: There is disclosed a sensor system comprising a sensor for detecting and signaling the presence of a fluid in an enclosure. The sensor system can be installed or incorporated within electronics and communications enclosures that house fluid-sensitive components and is useful in the early detection and warning of fluid leaks into such enclosures. In addition to the sensor, the system includes a means for conducting fluids entering the enclosure to the sensor and absorbent material to absorb any entering fluid.

Abstract: To discriminate optically between the various phases in a three-phase fluid, a light beam (F) of non-zero divergence is injected into a detector block (10) made of a material whose refractive index is greater than the refractive indices of all three phases of the fluid. The block (10) has a sensitive zone (18) and a total reflection zone (20) such that incident rays (Ri) parallel to the axis (12) of the block strike the sensitive zone (17) at an angle of incidence (.THETA.i) and are returned parallel to the axis (12) by the total reflection zone (20). The angle of incidence (.THETA.i) is such that a first phase gives rise to almost total reflection, a second phase gives rise to almost total transmission, and a third phase gives rise to partial transmission and partial reflection.

Abstract: There is disclosed an optical sensor comprising a light source, light detector and signal generator, and an optical fiber extending between the light source and detector. The optical fiber includes a sensing length comprising a return bend in the fiber, where the return bend has a bend radius less than or equal to 2.5 times the radius of the optical fiber. In one embodiment, the sensing length further includes a planar sensing surface. A method for detecting the presence of a medium in an environment using the optical sensor of the invention is also disclosed.

Abstract: In a method of determining the refractive index of a gaseous, liquid or solid sample, preferably a gaseous or liquid sample, there is used a waveguide resonator (1) which includes an open waveguide (4) and a closed waveguide (5) located adjacent the open waveguide. The sample is brought to the vicinity of the closed waveguide (5) so as to influence the proximal surroundings of the waveguide and therewith its effective refractive index. Light derived from a light source (9) is coupled to one end of the open waveguide (4) and transmitted light is measured at the other end of the open waveguide to establish the influence of the sample on the resonance wavelength and therewith determine the refractive index of the sample or a sample-related refractive index difference. A device for carrying out the method includes a waveguide resonator having a sample contact area (12) adjacent the closed waveguide (5) of the waveguide resonator.

Abstract: The present invention relates to a refractive index detector for a dynamic liquid sample having a fiber optic filament of a predetermined diameter with an unclad sensor region, wherein the sensor region comprises a longitudinally tapered zone wherein the diameter continuously decreases from the predetermined diameter to a minimum diameter.The invention finds use as a detector for high performance liquid chromatography and capillary zone electrophoresis.

Abstract: A refractive index sensor of a total-reflection type comprises a waveguiding layer of a cladding/core/cladding waveguide structure formed on a substrate. The waveguiding layer has an input face connected to either a single optical fiber or a plurality of optical fibers for injecting a light(s) into the layer, a detection face which, obeying Snell's law, totally reflects/transmits the light beam or beams that have arrived there with an expansion angle from the optical fiber or fibers and which constitutes a surface with which a material whose refractive index is to be measured comes in contact, and an output face which outputs the light reflected from the detection face and is connected to an optical detector. The refractive index of the material of interest is detected from a bright-dark boundary of the presence of the corresponding total reflected light from the detection face. With no need of a bulk prism or lamp-type light source, the sensor is small in size and high in sensitivity.

Abstract: The present invention relates to a fluid detection system which can be adapted for use in applications including liquid-level detection, pipeflow monitoring, and interstitial leakage in double-walled containers. The system operates on principles of optics and provides the capability of remotely differentiating between fluids having different refractive indices including liquids and vapors. The present detector uses a unique light pulsation technique which increases permissible operating ranges over existing optical detection systems.

Abstract: A gas density sensor having a prism in contact with a fluid whose density is determined. A light source shines light into the prism. The light is reflected off prism surfaces in contact with the fluid. As the fluid density changes, the amount of light reflecting off these surfaces changes depending upon fluid density. A detector placed to receive light reflecting off the surfaces determines density from sensed light.

Abstract: According to the present invention, there is provided an optical sensor capable of detecting, identifying or measuring a property of a solid, liquid or gas which is in contact with its measuring surface. The preferred sensor comprises an optically transparent sensing element with at least one surface, an optical energy source, means for conducting optical energy from the source to the sensing element at a specific, precisely determined angle and a photodetector. The measuring surface of the sensing element forms an interface with the substance to be measured. Optical energy is partially reflected from the interface formed at the planar surface of the transparent element toward the photodetector. It has been discovered that the resulting signal from the photodetector is proportional to the refractive index of the medium covering the outer surface of the transparent element.

Abstract: An optical probe head for determining the index of refraction of a sample, which is made up of a gradient index lens in contact with the sample, a transmitting optical fiber for inputting radiation into said gradient index lens and a receiving optical fiber. The optical fibers and gradient index lens are aligned so that radiation from the transmitting optical fiber which is reflected from the interface of the gradient index lens and the sample is received by the receiving optical fiber. The probe can, with slight changes, also be used for determining the Raman or fluorescent spectra, for determining the absorption spectrum, and for determining the self-referencing transmission of a sample.

Abstract: An apparatus useful in immunoassay of a fluid, light is directed to an optical sensor wherein the light is transmitted to a replaceable optical device that is responsive to index of refraction in a sensing region thereof that is exposed to the fluid. One portion of the light is transmitted via a compensation path that includes the sensing region to a first detector. Another portion of the light is transmitted via a sensing path that includes the sensing region to another detector. In one embodiment a ratioing device receives an output from each detector and provides a signal responsive to the ratio of the outputs. The replaceable optical device typically comprises a pair of channel waveguides in directional coupling arrangement, or a pair of channel waveguides in an interferometer arrangement, or a ridge waveguide having a curved or serpentine path configured so that nonspecific sensing effects are compensated.

Abstract: An apparatus is disclosed for measuring the refractive index of index matching gels. A light source (10) is directed into one (20) of the output legs (20, 22) of an optical splitter (18), where the input leg (26) is interconnected to a fiber optic cable (27). The end of the cable (27)is inserted into the gel (30) to be measured. The incident light source (10) directs an incident light source through the splitter, and through the end (29) of the fiber optic cable (27). The difference in refractive indexes between the fiber optic cable (27) and the gel (30) causes a reflection of the incident light back to the splitter (18) and through a measuring device (52). By measuring the reflected power, and by knowing the incident power and other known factors, the refractive index of the gel can be calculated.

Abstract: A fiber optic refractometer is disclosed for use in on-line measurement of the refractive index of a process fluid. The refractometer does not require light to pass through the process fluid and is hence unaffected by the presence of light diffusing particulate matter in the process fluid. A particular application for which the refractometer is well-suited is the on-line measurement of the hydrogenation state of edible oils (which correlates with refractive index) during the partial hydrogenation process.

Abstract: In a refractive index type optical sensor having a thin film metal clad on a waveguide to control leakage of light as a function of refractive index, light leakage occurs in the region where a discontinuity in refractive index occurs. A discontinuous clad with short, closely spaced segments maximizes light leakage and sensitivity over the length of the sensing region. Multiple sensing regions can be formed on a single waveguide.

Abstract: A radiation transmission fiber for spectroscopic monitoring includes a transmission portion and a sensor portion; the transmission and sensor portions have a continuous core portion and continuous cladding over the core portion throughout the transmission and sensor portions; the sensor portion of the core is of smaller diameter than the transmission portion(s) and is connected to the transmission portion(s) by a conical transition portion(s); and the cladding in the transmission portion is of greater thickness than the cladding in the sensor region.

Abstract: A fiber-optic sensor is formed from three optical fibers. The distal ends of the fibers are optically linked by bonding their cores and directing their ends to mirrors. A portion of one of the fibers near the bonded point is exposed directly to the fluid to be sensed. The transmission characteristics of this fiber, the signal fiber, is then affected by the chemical constituents of the fluid. Light directed into the proximal end of one of the other fibers, the input fiber, is split between the signal fiber and the remaining fiber, the reference fiber. The ratio of the light in the signal fiber to the light in the reference fiber provides an indication of the chemical constituents that minimizes errors introduced by factors such as bends in the fibers and temperature.

Abstract: An apparatus and method for in situ monitoring the viscosity and cure of resins using viscosity dependent fluorescence uses a fiber optic waveguide to introduce light to the resin of a wavelength exciting fluorescence and to conduct the emitted light to a monitor. The emitted light parameters correlate to the viscosity and cure conditions of the resin. The apparatus and method may be used to control composite construction and to provide information on the in service condition of composites.

Abstract: A refractive index sensor senses the refractive index of a mixed liquid and generates a corresponding signal. A temperature sensor senses the temperature of the liquid and generates a corresponding signal. A signal mixer mixes the refractive index signal and the temperature signal with each other to provide a single mixed signal which is then fed through a single signal line to a liquid content calculator where the sensed refractive index is modified based on the sensed liquid temperature to provide a temperature compensated refractive index from which the content of a liquid component in the liquid is calculated. This simplifies the arrangement of the entire apparatus and improves the operational reliability thereof as compared with the case in which the two signals are separately supplied to the liquid content calculator through two signal supply systems.