# US 2018/0024052 A1 · Immersion Refractometer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0024052 A1 - Document ID: US20180024052A1 - Status: Published application - Kind: A1 - Application number: 15/218,494 - Filed: 2016-07-25 - Published: 2018-01-25 - Earliest claimed: 2016-07-25 - Assignees: Joseph Samuel Accetta - Inventors: Joseph Samuel Accetta - Web page: https://patentgrep.com/patent/US20180024052A1 ## CPC - G01N 21/41: Refractivity; Phase-affecting properties, e.g. optical path length (G01N21/21 takes precedence) - H01M 10/484: {for measuring electrolyte level, electrolyte density or electrolyte conductivity} - G01N 21/4133: {Refractometers, e.g. differential} - G01N 21/431: {Dip refractometers, e.g. using optical fibres} - G01N 2021/414: {Correcting temperature effect in refractometers} - Y02E 60/10: Energy storage using batteries - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A device for measuring the absolute value of the refractive index of a liquid by immersion uses the optical properties of a cylindrical waveguide with a solid core and normal angle of incidence of the light source. The device consists of a transparent tube forming the enclosure of the waveguide, impervious to the surrounding liquid and partially filled with a transparent solid or liquid material of appropriate index of refraction, a fiber optic means of inputting light via a LED or laser and fiber optic means of coupling emerging light to a photodetector. The emerging light intensity is a function of the index of refraction of the surrounding liquid. ## Claims ### Claim 1 A device for measuring the refractive index of a liquid comprising a transparent tube partially filled with a solid or liquid transparent material, a fiber optic means of inputting light via an LED or laser and a fiber optic means of coupling emerging light to a photodetector such that the input light and emerging light are at the same end of the tube. ### Claim 2 (depends on 1) The device in claim 1 wherein the tube is made of quartz or other high index transparent material such that its refractive index is much greater than the transparent fill material to minimize the effects of the tube enclosure. ### Claim 3 (depends on 1) The device of claim 1 wherein the tube that is of sufficient length to subtend the liquid such that the active region is fully immersed. ### Claim 4 (depends on 1) The device of claim 1 wherein the transparent tube filling material consists of air or gas with sufficiently low refractive index that renders the device insensitive to refractive index changes of the surrounding liquid such that liquid level sensing via Fresnel reflections along the axis of the tube can be affected. ### Claim 5 (depends on 1) The device of claim 1 wherein the refractive index of the tube filling material is equal to or exceeds the upper limit of the refractive index range of the surrounding liquid as described in FIG. 1 and is appropriate to a specific application such as battery state of charge sensing, sugar content of certain distillates, sugar content of urine, anti freeze concentrations and other specific applications where refractive index is significant in the monitoring or manufacturing of liquids. ### Claim 6 (depends on 1) The device of claim 1 wherein the fiber optic means of inputting and outputting light fibers are comprised of one or more fibers bundled together within a ferrule is such that light enters and exits at the same end of the device. ### Claim 7 (depends on 1) The device of claim 1 further comprising a reflecting mirror at the end of the tube positioned orthogonally to the optical axis of the tube such that the incident light traverses the core region twice effectively increasing the active length by a factor of 2. ### Claim 8 (depends on 6) The device of claim 6 wherein the input fiber bundle is parallel to the tube axis without regard to specific angle of impingement on the interface between the guide and the solid material. ### Claim 9 (depends on 1) The device of claim 1 further comprising an enclosure that is mechanically compatible with open port batteries. ### Claim 10 (depends on 1) The device of claim 1 further comprising a small temperature sensing element such as a thermocouple or thermistor inserted within the ferrule to enable the monitoring of liquid temperature thus allowing correction of the variation of the index of the surrounding liquid with temperature. ### Claim 11 (depends on 6) The device of claim 6 wherein the tube ferrule enclosing the fiber bundle is made with a light absorbing material to minimize the effects of Fresnel reflections between the ferrule and the tube wall beyond the active length of the probe. ### Claim 12 (depends on 1) The device of claim 1 wherein the light source operates in the IR with wavelengths >700 nm to minimize ambient light interference. ### Claim 13 (depends on 1) The device of claim 1 whereas the fiber optic means by which the light enters the tube material is through an optical window separating the material and the fiber bundle. ### Claim 14 (depends on 1) The device of claim 1 wherein an electronic self calibration may be affected by using the refractive index of air as a calibration standard. ### Claim 15 (depends on 1) The device of claim 1 further comprising a battery, microprocessor and display such that the output of the device may be converted and displayed in calibrated engineering units appropriate to the specific application as shown for example in FIGS. 6,7. ### Claim 16 (depends on 1) The device of claim 1 wherein a practical embodiment of the device may be used in battery powered vehicles as a “fuel gauge”. ### Claim 17 (depends on 1) The device of claim 1 wherein a practical embodiment of the device may be used in battery monitoring systems for function assurance. ### Claim 18 (depends on 1) The device of claim 1 wherein a practical embodiment of the device may be used in battery charging systems for precision charging control.