Structured-light velocimeter angular velocity sensing

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Solution Overview

Problem

Existing methods for measuring fluid angular velocities are limited by the need to first measure linear velocity components, which introduces spatial and temporal resolution trade-offs, making it difficult to capture rapidly changing flows.

Innovation Solution

The implementation of angular-velocity sensing using structured-light velocimetry, where a tracer particle is illuminated by an optical beam with transverse structure, allowing direct measurement of angular velocity without requiring prior measurement of linear velocity components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If numerical differentiation is used to calculate angular velocity from linear velocity fields, then angular velocity can be derived, but spatial resolution deteriorates due to inherent spatial uncertainty

Engineering Contradiction:

Improveangular velocity measurementVSAvoidspatial resolution

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

Instead of calculating angular velocity from linear velocity measurements, the patent inverts the approach by directly measuring angular velocity using structured light illumination. The tracer particle is illuminated by an optical beam with transverse structure (angular fringes) that modulates scattered light based on angular position, enabling direct angular velocity measurement without numerical differentiation.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent replaces the computational/mathematical approach (numerical differentiation of velocity fields) with a direct optical measurement system. Structured light modulation and photodetector signal processing substitute for the mathematical operations that previously degraded spatial resolution.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If the density of field samples is increased to improve spatial resolution, then spatial resolution improves, but temporal resolution deteriorates

Engineering Contradiction:

Improvespatial resolutionVSAvoidtemporal resolution

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent extracts only the angular velocity information directly from the flow field using structured light illumination, rather than measuring the complete linear velocity field and processing it. This selective measurement approach reduces the data acquisition burden and improves temporal resolution while maintaining spatial resolution.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If conventional particle-tracking velocimetry with Gaussian or flat-top beams is used, then linear velocity can be measured, but angular velocity measurement capability is lost

Engineering Contradiction:

Improvelinear velocity measurementVSAvoidangular velocity measurement capability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies structured light with specific transverse intensity patterns (angular fringes) to the tracer particle. This localized structural illumination creates a modulation pattern in the scattered light that encodes angular position information, enabling angular velocity measurement while the particle traverses the beam.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the illumination beam parameters from conventional Gaussian or flat-top profiles to structured beams with transverse intensity variations. This parameter change in the optical beam structure enables the extraction of angular velocity information from the modulated scattered light signal.

Inventive Principle:

Principle #35Parameter changes

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

This approach enables measurements with high temporal and small spatial resolutions, effectively capturing rapid changes in fluid flows and improving the understanding of turbulent dynamics.

Implementation Method 1

the tracer particle is illuminated by an optical beam that has transverse structure (e.g., angular fringes) of varying intensity that modulate the amount of light scattered by the tracer particle

Methodology Applied

Scientific EffectLight scattering: Scattering

Data Source

PatentUS12313648B2Structured-light velocimeter and velocimetry method

Publication Date: 2025.05.27 PRESIDENT & FELLOWS OF HARVARD COLLEGE

AI summary

A structured-light-velocimetry method includes extracting one or more bursts from a time-varying signal generated by detecting scattered light from a tracer particle passing through a structured optical beam; fitting each of the one or more bursts to a multi-variable model to extract a plurality of fitted parameters; and executing a machine-learning model with the plurality of fitted parameters to predict an angular velocity of the tracer particle.