Abstract: An inexpensive, optical position sensor for measuring a position or length, x, along a one-dimensional curvilinear, coordinate system. The sensor can be used, for example, to determine the position of an interface between a clear and an opaque fluid (such as crude oil and water). In one embodiment, the sensor utilizes the principle of dual-fluorescence, where a primary fiber emits primary fluorescent light and a parallel secondary fiber collects a portion of the primary fluorescent light that is not blocked by the opaque fluid. This, in turn, excites secondary fluorescence in the secondary fiber at a longer wavelength. A light detector measures the intensity of secondary fluorescence emitted from an end of the secondary fiber, which is used to calculate the unknown position or length, x. Side-emitting fibers can be used in place of, or in addition to, fluorescent fibers. The all-optical sensor is attractive for applications involving flammable liquids.

Abstract: A non-mechanical fluid level sensor based on light communication channel (LCC) technology. In a preferred embodiment, one end of the LCC is connected to a signal source while another end is connected to a sensor. The LCC is dipped in a fluid container and a signal propagates and undergoes internal reflection through the LCC towards one of its ends which is connected to the sensor. The fluid level is detected preferably by measuring the intensity of the signal reflected with the LCC that reaches a sensor. Different fluid levels preferably correspond to linearly varying detected signal intensities. A main LCC bus may communicate remotely with the sensor without wiring or other electrical connectors.

Abstract: In a method of optically determining a level of liquid in a liquid-filled container a light guide body projects into the container. The light guide body has an end face for the entry and exit of light and stepped side faces forming separate reflection faces. The light is totally reflected at those reflection faces which are not immersed in the liquid but refracted into the liquid at immersed reflection faces. The totally reflected light is reflected back to the end face. The intensity of the light beam reflected totally by each reflection face back to the end face is measured separately. Measurement signals for determining the filling level are subjected to plausibility checking to recognise and eliminate measurement faults and errors. The invention can be used for determining the level of liquid in a container or tank for fuel, washing water, oil, hydraulic fluid and the like in a motor vehicle.

Abstract: The present invention provides a highly universal out-of-liquid sensor that allows an out-of-liquid condition to be accurately detected for a long time, and provides a liquid supply device using the same.

Abstract: A photo-curing light system in which a modulation of the light intensity or output is controlled via an analogue control voltage to the control line output of the lamp power supply. The control signal results in the lamp current being reduced from its maximum value to a lower value on a continuous and repeated basis thereby modulating the light and reducing the heating value to surrounding material such as tooth structure during the curing process.

Abstract: A liquid supplying device comprising a liquid container for storing a liquid so as to supply an external device and a liquid level sensor for detecting the liquid level. As the liquid within the liquid container is gradually used up, liquid level drops. As soon as the remaining liquid in the container drops to a predetermined amount, the liquid level sensor emits a warning signal to the operator, and the operator can then replenish the liquid in the container.

Abstract: A liquid level sensor comprising a transparent waveguide containing fluorescent material that is excited by light of a first wavelength and emits at a second, longer wavelength. The upper end of the waveguide is connected to a light source at the first wavelength through a beveled portion of the waveguide such that the input light is totally internally reflected within the waveguide above an air/liquid interface in a tank but is transmitted into the liquid below this interface. Light is emitted from the fluorescent material only in those portions of the waveguide that are above the air/liquid interface, to be collected at the upper end of the waveguide by a detector that is sensitive only to the second wavelength. As the interface moves down in the tank, the signal strength from the detector will increase.

Abstract: A liquid level monitor uses a tube to confine a float to a vertical path with a canister containing a lower liquid and an upper liquid which meet at a liquid boundary, the level of which is to be monitored. Light from a light-emitting diode is conveyed to a vertical position of the tube by an optical fiber. A second optical fiber is arranged in a diametrically opposed position of the tube to detect light transmitted across the tube from the first optical fiber. The float is more transmissive than either liquid. When the level of the boundary falls to the level of the optical fibers, received light increases. The second optical fiber conveys this return light to a photodetector, the output of which can be used to trigger an alarm indicating that the boundary level is low.

Abstract: Apparatus for detecting fluid level in a container, comprises a housing adapted to be disposed in the container; a float with an associated magnetic element, the float position corresponding to fluid level in the container; a magnetostrictive sensor disposed inside the housing; and a stick gauge disposed inside the housing; the magnetostrictive sensor and the stick gauge each being operable to determine the float position.

Abstract: A liquid gauging system for a liquid container, the system comprising sensor means for producing a first electromagnetic signal that corresponds to liquid quantity in the container, and remote interrogation means for receiving the first electromagnetic signal and producing a system output that corresponds to the liquid quantity; the sensor means being energized by a second electromagnetic signal transmitted by the remote interrogation means.

Abstract: A method of measuring the position of a liquid surface within a vessel is scribed. An optical fiber is provided which has first and second ends and has an energy-absorbing element of a predetermined length disposed upon a portion of the cladding thereof such that there is a thermal interface between the energy-absorbing element and the cladding. The optical fiber is then positioned in the vessel so that the energy-absorbing element disposed thereon extends a known distance into the vessel along a known depth gradient of the vessel and so that the energy-absorbing element will intersect the liquid surface over the anticipated range of positions thereof. Single-frequency, coherent light is then transmitted through the core of the optical fiber by launching it into the first end of the optical fiber. A pulse of energy is applied across the entire length of the energy-absorbing element to heat it, and then the transmitted light is received from the second end of the optical fiber.

Abstract: A fiber optic detection system in which a single optic fiber has a U-shaped configuration. A source of light is disposed at one upper free end of the optic fiber and a light detector is disposed at the other upper free end of the optic fiber. At the bottom of the optic fiber is a light variable loop adapted to be disposed in various media, such as liquids, fluids and air. The light from the source of light is conducted from the source of light through the optic fiber and to the light detector. The quantum of light lost as the light travels through the light variable loop will depend on the medium or the concentration of the medium in which the light variable loop is disposed. The light detector detects the light advancing thereto to produce a signal representative of the medium or the concentration of the medium in which the light variable loop is disposed.

Abstract: A moveable body, cladding medium, and fiber are arranged to form a sensor suitable for use in monitoring changes in liquid, fluid, and material level and changes in pressure. The moveable body moves in response to changes in pressure or force. Movement of the body causes a change in the length of cladding medium surrounding an optical fiber. As the extent of cladded fiber length changes, the intensity of light transmitted through the fiber also changes.

Abstract: A fiber optic fuel or liquid level gauge is disclosed which determines the liquid level by measuring the amount of light loss due to evanescent transfer to the fuel or liquid. An optical fiber is supported in the fuel or liquid tank, with a first end adjacent the highest possible liquid level to be measured with a reflector at the first end. The optical fiber extends downwardly through the tank, and its second end is connected to a light source for injecting light into the fiber. The intensity of the input light is compared to the intensity of light reflected from the first fiber end, and the liquid level is calculated from the light loss. The gauge has very high reliability since it has no moving mechanical parts.

Abstract: A fiber optic fuel or liquid level gauge is disclosed which determines the liquid level by measuring the amount of light loss due to evanescent transfer to the fuel or liquid. An optical fiber is supported in the fuel or liquid tank, with a first end adjacent the highest possible liquid level to be measured with a reflector at the first end. The optical fiber extends downwardly through the tank, and its second end is connected to a light source for injecting light into the fiber. The intensity of the input light is compared to the intensity of light reflected from the first fiber end, and the liquid level is calculated from the light loss. The gauge has very high reliability since it has no moving mechanical parts.