Hemispherical Lens Optical Fiber Liquid Detection

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Solution Overview

Problem

Existing fiber optic sensing systems for detecting liquids in underground fuel tanks face challenges with light attenuation and discrimination between different mediums, such as water, alcohol, and gasoline, due to refractive index differences and optical impurities, leading to inefficiencies in detecting leaks or groundwater ingress.

Innovation Solution

A novel optical sensing system utilizing a hemispherical lens and optically translucent material with precisely positioned optical fibers, integrated with a microprocessor and a detangler mechanism, which enhances light transmission and detection by using evanescent and whispering gallery modes, and includes a tamper feature to prevent false readings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a return bent optical fiber is used for liquid detection, then the system can detect the presence of water or fluid, but light attenuation occurs and discrimination between different mediums becomes difficult

Engineering Contradiction:

Improveliquid detection accuracyVSAvoidlight attenuation

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent employs a hemispherical lens at the tip of the optical fiber to focus and direct light effectively. The curved spherical shape optimizes light transmission through the lens while minimizing attenuation, allowing for precise liquid detection by enhancing the optical path and interaction with the medium being tested.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Adaptability or versatility

If optical fibers are positioned to detect light intensity for fluid discrimination, then detection capability is provided, but optical impurities interfere with discrimination between different mediums

Engineering Contradiction:

Improvefluid discrimination capabilityVSAvoiddetection accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces a lens as an intermediary component between the optical fiber and the medium being tested. This lens focuses the light and enhances the evanescent field interaction, serving as a mediator that amplifies the optical signal while filtering out interference from optical impurities, thereby improving both fluid discrimination capability and detection reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent utilizes changes in the optical parameters (such as evanescent field strength and light intensity) when different fluids are present. By monitoring these parameter changes and comparing them against known characteristics of different fluids (water, alcohol, gasoline), the system achieves reliable discrimination between mediums despite the presence of optical impurities.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If existing fiber optic sensing systems are used, then liquid detection is possible, but the system cannot reliably distinguish between different types of liquids due to refractive index differences and optical impurities

Engineering Contradiction:

Improvefluid detection rangeVSAvoidfluid type discrimination

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent replaces traditional mechanical or chemical sensing methods with an enhanced optical sensing system. By using a lens-coupled optical fiber arrangement that exploits evanescent field interactions and light intensity measurements, the system achieves precise fluid type discrimination across a wide range of substances (water, alcohol, gasoline, mixtures) without the limitations of refractive index-based methods alone.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively discriminates between air, water, alcohol, and gasoline based on light intensity, providing accurate fluid detection and tamper indication, improving the reliability and safety of fuel tank monitoring.

Implementation Method 1

enhances light transmission and detection by using evanescent and whispering gallery modes

Methodology Applied

Scientific EffectEvanescent modes:

Implementation Method 2

enhances light transmission and detection by using evanescent and whispering gallery modes

Methodology Applied

Scientific EffectWhispering gallery modes:

Implementation Method 3

Light is transmitted into one end of the fiber, and a photosensitive component provides a measure of the intensity of light leaving the other end

Methodology Applied

Scientific EffectOptical fiber transmission: Optical Fibre

Implementation Method 4

detect the presence of liquid (such as water, alcohol, petroleum products, or a mixture thereof) between the walls of a double-walled underground fuel tank

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS8084731B2Sensor system for liquid detection with lens component having an apex

Publication Date: 2011.12.27 JOHNSON DOUGLAS M

AI summary

A light transmitting optical fiber shines light at a side edge portion of a hemispherical lens. The light is transmitted along the outer periphery of the lens to a second side edge portion located opposite the first side edge portion. A light sensitive component detects light at the second edge portion which light originated at the first side edge portion. The intensity of light detected at the second side edge portion is indicative of the fluid to which the lens is exposed.