Acousto-optic Light Localization in Scattering Media

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Solution Overview

Problem

Existing methods for light measurements in light-scattering media, such as biological tissue, are limited by shallow penetration depth and poor spatial resolution due to strong light attenuation by scattering.

Innovation Solution

A device and method utilizing acoustic-frequency-shifted laser light and optical components, including an ultrasonic device to create an acoustic field within the medium, and a slow-light filter to detect frequency-shifted light, enabling deeper light penetration and improved spatial localization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional optical methods are used for light measurements in light-scattering media, then spatial localization can be achieved, but penetration depth is limited to shallow layers due to strong light attenuation

Engineering Contradiction:

Improvelight penetration depthVSAvoidlight attenuation by scattering

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent introduces acoustic waves as an intermediary to modulate the optical properties of tissue. By applying acoustic radiation pressure through ultrasonic waves, the refractive index of tissue is dynamically modulated, creating an acoustic-optical interaction that enables light to penetrate deeper while maintaining spatial localization through frequency-tagged detection

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical state of light interaction with tissue by using acoustic modulation to dynamically alter the refractive index. This parameter change allows light to be frequency-shifted by the acoustic frequency, enabling detection of depth-resolved information through spectral filtering of the frequency-tagged light

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If light is used to probe deep into light-scattering media, then penetration depth increases, but spatial resolution deteriorates due to diffuse scattering

Engineering Contradiction:

Improvelight penetration depthVSAvoidspatial resolution

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent uses frequency shifting of light by acoustic waves as a form of 'color change' in the optical domain. The acoustic frequency acts as a spectral tag that identifies light photons that have interacted with the acoustic field at specific depths, enabling spatial resolution to be recovered through frequency-domain filtering despite deep penetration

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The patent applies acoustic modulation before light detection to pre-tag the light photons with depth information. By creating the acoustic field at the target depth beforehand and allowing light to be frequency-shifted during its passage, the system prepares the light signal with spatial encoding that can be decoded later through spectral analysis

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If photoacoustic methods are used to improve spatial localization, then spatial resolution improves, but light penetration depth remains limited due to strong scattering attenuation

Engineering Contradiction:

Improvespatial localizationVSAvoidlight penetration depth

Core Design Contradiction:

Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent inverts the conventional photoacoustic approach by not detecting acoustic waves generated by light absorption, but rather detecting light that has been frequency-shifted by acoustic waves. This inversion allows the benefits of acoustic spatial localization to be achieved while maintaining the deep penetration capability of optical methods

Inventive Principle:

Principle #13The other way round (Inversion)

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 allows for higher light intensities and improved spatial resolution deep within light-scattering media, enhancing the ability to perform localized measurements and imaging, such as oxygen saturation mapping in tissue.

Implementation Method 1

acoustic-frequency-shifted laser light

Methodology Applied

Scientific EffectAcousto-optic effect: Acousto-optic Effect

Implementation Method 2

slow-light filter to detect frequency-shifted light

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

diffuse light scattering dominates the interaction of the light field and the medium

Methodology Applied

Scientific EffectLight scattering: Scattering

Data Source

PatentUS20250072755A1System for localising light in light-scattering media

Publication Date: 2025.03.06 DEEP LIGHT VISION AB

AI summary

A system for light measurements in a subject, the system comprising at least one ultrasound transducer (13) configured for directing an ultrasound field with an ultrasound frequency to a location (15) inside a tissue site of the subject; at least one laser (12) configured for emitting light within a wavelength-range of infrared (IR), visible or ultraviolet light, and for directing light of a certain frequency to the tissue site; at least one optical filter (14) arranged before at least one light detector, the filter configured for suppressing the incident light frequency, but for transmitting light shifted by the ultrasound frequency to be detected by the light detector; and at least one light-reflecting member (16,17) configured to be arranged on a surface of the tissue site of the subject.