Abstract: The present invention provides a hollow prism for detecting liquid level in the presence of an optical beam, including a hollow member, dielectric members sealed to the hollow member with one of the dielectric members arranged at an inclined angle to the other, a sealed hollow space disposed between said dielectric members, wherein an incident optical beam enters through the first dielectric member at normal incidence and exits as an emergent beam through the second dielectric member, and wherein the emergent optical beam remains undeviated when the hollow member not immersed in a liquid medium and the emergent beam suffers deviation when immersed in the liquid medium. The present invention also provides a fiber optic liquid level detector with the hollow prism for detecting liquid levels.

Abstract: A bleed valve assembly includes a control assembly having a fluid inlet and a fluid outlet. The control assembly defines a fluid passageway in fluid communication with the fluid inlet and the fluid outlet. An electromechanical valve is engaged with the control assembly. The electromechanical valve provides selective fluid communication between the passageway and the fluid outlet. A fluid sensor is in fluid communication with the passageway. The fluid sensor includes a sensing tip and is in electrical communication with the electromechanical valve. A valve is disposed in the passageway of the control assembly. The valve prevents fluid communication of non-gaseous fluid between the fluid inlet and the fluid outlet.

Abstract: An optically-based overfill detection probe is provided that has a prism made of a fluoropolymer, preferably TEFLON® PFA. The prism material has a high resistance to chemical solvents, is less prone to condensation and frost than plastic or glass, and enables the production of prisms at significantly less cost than glass. The probe also includes a two-piece housing structure that compresses an outwardly-extending portion of the prism material to firmly hold the prism in place, and forces the material into sealing contact with an inner surface of the housing. The housing has an elongate portion that encompasses the prism, and which extends toward the fluid, preventing any light which escapes the prism from being externally reflected back to the photodetector of the probe.

Abstract: An optically-based overfill detection probe is provided that has a prism with a substantially quadrilateral cross-sectional shape, such that internal reflection angles are less than ninety degrees. The prism is made of a fluoropolymer, preferably TEFLON® PFA, and uses an infrared optical signal. The prism material has a high resistance to chemical solvents, has high signal transmission in the infrared (IR) wavelength range, is less prone to condensation and frost than plastic or glass, and enables the production of prisms at significantly less cost than glass. The substantially quadrilateral cross-sectional shape of the prism, in itself, has the advantage of allowing angles of incidence much less than ninety degrees on internal prism surfaces, thus reducing signal loss from surface irregularities.

Abstract: Disclosed is a liquid detection device wherein a condition in which there is no liquid remaining in either a storage member or a tank and a condition in which there is liquid remaining in at least either the storage member or the tank are easily discriminated using a single mechanism. When there is oil (liquid) remaining in at least either the oil tank or the impregnated member (storage member), light emitted from a light emitting part is passed into the oil through a prism face located partway along the light path, and does not reach a light receiving part. On the other hand, when there is no oil remaining in either the oil tank or the impregnated member, the emitted light reaches the light receiving part. When the oil tank itself is not mounted, the light emitted from the light emitting part also reaches the light receiving part. When the light emitted from the light emitting part is not detected by the light receiving part, a controller determines that there is oil.

Abstract: An apparatus and method for optical sensing of liquid level in cooking vessels are disclosed. The apparatus comprises: a first sensor (P1) for detecting a liquid and generating a first signal indicating a vessel level of the detected liquid above a desired liquid level (110) in the cooking vessel (102); a second sensor (P2) for detecting the liquid and generating a second signal indicating the vessel level of the detected liquid below the desired liquid level (110) in the cooking vessel (102); a third sensor (P3) for detecting the liquid and generating a third signal indicating the vessel level of the detected liquid (110) at the bottom of the cooking vessel (102); and a controller (108) for receiving the signals and for determining the vessel level in the cooking vessel (102).

Abstract: A bleeder valve comprising a housing including a sensor device of material which is optically denser than gas arranged between a light transmitter and a photo-electric receiver, at least one external surface of the sensor device being disposed in a space to which gas or hydraulic fluid is admitted; when gas is in contact with the external surface, light reaches the receiver and when hydraulic fluid is in contact with the surface, light does not reach the receiver, an output signal is generated by the receiver which causes a magnetic valve to open until gas is exhausted.

Abstract: A liquid sensing apparatus for a fuel tank comprises a first optical sensor for producing an output having a first state that corresponds to the first optical sensor being exposed to air and a second state that corresponds to the first optical sensor being exposed to fuel; and a circuit for detecting the first and second optical sensor output states. The sensor circuit also has self test capability for testing both active and passive components. The sensor circuits can be accessed using a two wire only interface, and thermal stability can be achieved with the electronic circuit as shown.

Abstract: An inexpensive ink tank having an ink remaining amount detection section which can be used with ink of any color is disclosed. An optical ink detection section formed from a light transmitting material has an inclined interface and is formed integrally with the ink tank. Incident light from a light source is refracted, when ink is present in the ink tank, at the interface to make refraction light and does not emerge to a visual observation portion. When no ink is present, the incident light is totally reflected by the interface to make total reflection light, which can be visually observed at the visual observation portion. A roughened face is formed at the visual observation portion so that light emerging to the visual observation portion may be scattered to facilitate visual observation.

Abstract: A liquid sensing apparatus for a fuel tank comprises a first optical sensor for producing an output having a first state that corresponds to the first optical sensor being exposed to air and a second state that corresponds to the first optical sensor being exposed to fuel; a second optical sensor for producing an output having a first state that corresponds to the second optical sensor being exposed to air or water, and a second state that corresponds to the second optical sensor being exposed to fuel; and a circuit for detecting the first and second optical sensor output states. The sensor circuits can be accessed using a two wire only interface, and thermal stability can be achieved with the electronic circuit as shown.

Abstract: An optical point level sensor for fluids includes a prism exposable to a fluid such that electromagnetic energy is reflected internally the prism dependent on the fluid level; and a lens optically connectable to an electromagnetic energy source and an electromagnetic energy detector such that electromagnetic energy from the source enters the lens at a first location axisymmetric to a second location where electromagnetic energy exits the lens to the detector. In one embodiment the lens is a GRIN lens.

Abstract: A fiber optic sensor for determining the presence and/or measuring the depth of a first substance capable of transmitting light. The fiber optic sensor includes a plurality of light receiving fibers, a plurality of light transmitting fibers surrounding the light receiving fibers and structure for refracting light from the light transmitting fibers at a predetermined angle for total internal reflection of the light from an interface of the first substance with a second substance.

Abstract: In its preferred embodiment, a one-piece optical-prism sensor of liquid level internally incorporates waveguide structure, i.e., within the otherwise conventional conical external profile of the prism, the waveguide being a thin flat member which includes three parallel spaced axes, namely, the axis of light input, the central axis of the cone, and the axis of detection of such light as exits the prism. The conical shape of the prism is essentially a hollow conical shell, within which the waveguide extends in essentially a single diametrical plane, with integral connection of the shell to the diametric limits of the waveguide. The net result is that light enters the waveguide on the input axis and, to the extent that the light is internally reflected, the waveguide so confines internal reflection that scattering is very substantially reduced, and essentially all the internally reflected light will exit on the detection axis.

Abstract: A liquid level monitor for sensing the level of liquid in a tank or vessel, typically an automobile radiator, employing a probe with a light emitting diode and phototransistor mounted inside an enclosure, the enclosure having a transparent lens through which light can pass, and the lens having a prism configuration which diffuses or alters stray light which occurs by reflection off an interior core wall of the vessel and prevents the diffused or dispersed light from rendering the phototransistor conductive and possibly leading to a false indication or reading of liquid level. The light emitting diode is electrically excited with a high-intensity, short duration pulse, which improves the sensitivity of the monitor.

Abstract: An optical sensor, having serviceable electronics, for monitoring the level of a liquid within a vessel having an exterior and an interior and for providing an electrical signal on the traverse of the liquid level past the sensor. The sensor comprises a fitting adapted to traverse the vessel wall, the fitting including a window having a prism shaped interior face and a planar exterior face sealed into the fitting and providing a fluid-tight optical path from the vessel interior to the vessel exterior. The fitting includes a chamber adjacent the planar face of the window and an electronic module shaped to fit the chamber. The module has an optical face. A light source and a light detector are positioned in the optical face to provide substantially zero clearance light communication between the window and both the source and the sensor, when the module is positioned within the chamber.

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 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 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 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 source fibre illuminates the interior of the substrate so that light exiting the source fibre is coupled to the detector fibre when total internal reflection at the substrate/fluid 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, due to the loss of light into the fluid by refraction. The mechanism for coupling light into the detector fibre is fluorescence within that fibre causing it to provide a light signal which varies with the level of the second fluid. Several different embodiments, to achieve continuous level sensing or the sensing of other parameters, are disclosed.

Abstract: A device for determining surface moisture, especially of absorbent materials, comprises a Dove reflection prism, a radiation source of such a design that its beams, which are aligned parallel, perpendicularly strike one of the two small surfaces of the prism, a light trap which traps the light beams emanating from the other small surface, and a photoelectric transducer which is located in the angle formed by the two small surfaces and is arranged such that its measurement surface is located parallel and opposite to the hypotenuse surface of the prism.