Evanescent Wave Focusing via Diffuser Temporal Inversion

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Solution Overview

Problem

Existing methods for focusing electromagnetic or acoustic waves lack precision, particularly in achieving a small focal spot size compared to the wavelength, which limits their effectiveness in applications such as radiocommunication and material processing.

Innovation Solution

The method involves using a diffuser, which can be an antenna, located close to the focal point, to convert evanescent waves into propagating waves, and then using temporal inversion of impulse responses to emit signals that recreate evanescent waves with high precision, achieving a focal spot size of around λ/30.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional focusing methods are used, then the wave can be focused at a focal point, but the focal spot size is large (comparable to wavelength)

Engineering Contradiction:

Improvefocusing precisionVSAvoidfocal spot size

Core Design Contradiction:

Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The patent applies preliminary action by placing diffusers at predetermined positions around the focal point before wave transmission. These diffusers are strategically positioned to intercept evanescent waves and convert them into propagating waves that can be focused precisely. The diffusers perform their wave-converting function in advance, enabling the subsequent temporal inversion technique to achieve super-resolution focusing with a focal spot size of approximately λ/30.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The diffusers serve as intermediary elements between the antenna array and the focal point. They mediate the wave transformation process by converting evanescent waves (which carry sub-wavelength information) into propagating waves. This intermediary conversion enables the system to access and utilize evanescent wave components that would otherwise be unavailable, thereby achieving enhanced focusing precision beyond the diffraction limit.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If diffusers are placed close to the focal point to improve precision, then focusing precision improves, but the device complexity increases

Engineering Contradiction:

Improvefocusing precisionVSAvoiddevice complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the wave transmission system into distinct functional components: the antenna array for wave emission, the diffusers positioned around the focal point for wave conversion, and the temporal inversion processing system. This segmentation allows each component to be optimized independently and facilitates the integration of the relatively simple diffuser elements with the antenna array, managing overall system complexity while achieving enhanced focusing precision.

Inventive Principle:

Principle #1Segmentation

3Volume of moving object

If evanescent waves are used for focusing, then sub-wavelength focal spot size is achieved, but the waves cannot propagate to the antennas

Engineering Contradiction:

Improvefocal spot sizeVSAvoidwave propagation

Core Design Contradiction:

Volume of moving objectVSSpeed

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies parameter changes by transforming the wave propagation characteristics through the diffusers. The diffusers change the wave parameters by converting evanescent waves (with exponential decay characteristics) into propagating waves (with oscillatory behavior). This parameter transformation enables the waves to both achieve sub-wavelength localization at the focal point and propagate effectively between the antennas, resolving the contradiction between localization and propagation.

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 significantly improves focusing precision, allowing for the creation of very small focal spots, enhancing the accuracy of wave transmission and reception, particularly in radiocommunication and material processing applications.

Implementation Method 1

an evanescent wave is produced at the point i, so that the diffuser or diffusers convert this evanescent wave into a propagating wave, which can propagate right to the antennas of the first array

Methodology Applied

Scientific EffectEvanescent wave conversion:

Implementation Method 2

the diffuser or diffusers then recreate evanescent waves from the received propagating wave, and these evanescent waves may be focused onto the point i with great precision

Methodology Applied

Scientific EffectEvanescent wave recreation:

Data Source

PatentUS8102328B2Method and device for the transmission of waves

Publication Date: 2012.01.24 UNIV PARIS CITE

AI summary

Method for focusing an electromagnetic or acoustic wave on a point near which one or more diffusers are placed, comprising a learning step in which the pulsed responses hij(t) between the focus point and each antenna of the network are determined. Waves corresponding to signals Sji(t)=Si(t)hij(−t), where Si(t) is a function of time and hij(−t) is a temporal inversion of the pulsed response hij(t), can then be transmitted form said antennas of the network.