A fuel gauging sensing device for a fuel tank for aircrafts includes an optical fiber harness along the internal surface of the tank, a master optical controller connected to a first terminal of the optical fiber harness, a slave optical controller connected to a second terminal of the optical fiber harness, wherein the optical fiber harness includes Fiber Bragg Grating (FBG) sensors spaced in the optical fiber harness between 1 mm and 25 mm to provide temperature gradients inside the tank and wherein the master and slave optical controllers are configured to obtain the fuel gauging of the tank based on the output from the FBG sensors.

A beverage dispenser ingredient level detection system is disclosed. The system may include a container with a wall, a canister, a capsule, an infrared emitter, and an infrared receiver. The canister may be disposed within the container at a first distance from the wall and may be configured to hold a beverage ingredient. The capsule may be disposed on an interior surface of the wall. The infrared emitter and the infrared receiver may be disposed within the capsule and the infrared receiver may be configured to transmit infrared light rays and the infrared receiver may be configured to detect infrared light rays reflected by the beverage ingredient in the canister to determine whether a pre-determined amount of the beverage ingredient is within the canister. The capsule may absorb infrared light rays that are not indicative of whether the pre-determined amount of the beverage ingredient is within the canister.

An illumination system can be configured for use with a liquid level gauge. A mounting bracket can be configured to secure a LED assembly to a frost-proof extension of the liquid level gauge, with the LED assembly disposed adjacent to a second edge face of the frost-proof extension that is opposite a liquid tube. The LED assembly can be thereby configured to illuminate the liquid tube via the second edge face of the frost-proof extension.

An optical probe that measures the level of a liquid in a tank includes a transparent and refracting optical waveguide for receiving an injection of a collimated light beam. The optical waveguide internally reflects the collimated light beam according to a total reflection regime in any part of the optical waveguide located in a gaseous medium and refracts the collimated light beam according to a refraction regime in any part of the optical waveguide immersed in a liquid medium. The optical waveguide switches from the total reflection regime to the refraction regime at the interface between the gaseous medium and the liquid medium, and mirrors are arranged around said optical waveguide and reverse the path of a light beam collimated and refracted by the optical waveguide, the optical path covered by the collimated light beam representing the level of the liquid in the tank.

A measurement system and method for liquid quantity in a receptable, the measurement system including a plurality of sensor units at various locations of the receptacle, the receptable including the liquid therein, each of the plurality of sensor units being on an outside surface of the receptacle, a data receiver coupled to the plurality of sensor units via one or more connectors and configured to receive measurements from the plurality of sensor units via the one or more connectors, and a processor coupled to the data receiver and configured to convert the received measurements from the plurality of sensor units to a measured quantity of liquid inside the receptable.

A fluid level sensing system includes a mounting strip and fluid sensing nodes coupled to the mounting strip. Each fluid sensing node is switchable between a fluid present state and a fluid absent state. Each fluid sensing node includes a prism, a photoemitter and a photoreceptor. The photoemitter and photoreceptor are interposed between the prism and the mounting strip. In the absence of fluid around the prism, the photoreceptor receives greater than a threshold amount of light from the photoemitter internally reflected by the prism to switch the fluid sensing node to the fluid absent state. When the prism is covered in fluid, the photoreceptor receives less than the threshold amount of light from the photoemitter to switch the fluid sensing node to the fluid present state. A processor determines a fluid level based on the fluid detection states of the fluid sensing nodes.

A subsidence sensing device with a liquid replenishing mechanism has multiple liquid storage tanks connected with each other via communicating tubes, multiple level sensors, a liquid feeding tank disposed higher than liquid surfaces of liquids in the liquid storage tanks, and an air inlet tube and a liquid feeding tube communicate the liquid in the liquid storage tanks and feeding liquid in the liquid feeding tank. When the liquids in the liquid storage tanks evaporate gradually due to surrounding temperature or humidity, the feeding liquid in the liquid feeding tank flows into the liquid storage tank and replenish all of the liquid storage tanks via the communicating tubes. Thus, the liquid surfaces of the liquids in the liquid storage tanks can be kept at a predetermined proper liquid level, so as to allow the level sensor to provide accurate signals to monitoring staffs.

A method of detecting liquid level of printing material of a three-dimensional printer includes steps of: (a) providing a printing material tank and a sensor, (b) injecting a printing material into the printing material tank, (c) outputting, by the sensor, a first voltage signal and continuously injecting the printing material when the sensor does not detect the printing material, and (d) outputting, by the sensor, a second voltage signal and stopping injecting the printing material when the sensor detects the printing material, wherein a voltage level of the first voltage signal is greater than a voltage level of the second voltage signal.

A liquid level detection system and a liquid level detection method comprising a light source, a light guiding medium, a photoelectric conversion receiver and a processing module is provided. The light guiding medium has an incident surface, a first reflection surface, and an exiting surface. The first reflection surface comprises a first sub-reflection surface and a second sub-reflection surface, with a liquid surface as a boundary line. When the light beam is incident on the first and second sub-reflection surfaces at the same angle, the refraction angle and light intensity loss is different, so there is an abrupt change in the generated light intensity image. The position of the abrupt change is the position of the liquid surface. The position of the liquid surface can thereby be obtained according to the position of abrupt change in light intensity after the light beam passes through the light guiding medium.

A liquid level sensing system provides a removable reservoir incorporating a reflective surface that can be interrogated by a stationary optical sensor in a receptacle receiving the removable reservoir. The optical sensor may detect the presence of the liquid within the reservoir without connection to the reservoir simplifying the process of making the reservoir removable while still allowing sensing of its contents. By aligning the optical axis with the insertion axis of the reservoir sensitive optical alignment problems are minimized.