s-SNOM Broadband Interferometer Phase Selection

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Solution Overview

Problem

Conventional Scattering Scanning Near-Field Optical Microscopy (s-SNOM) using broadband sources faces significant challenges in achieving high-speed chemical and optical imaging due to the need for extensive interferometric measurements at multiple phases, leading to impractically long acquisition times for hyperspectral images.

Innovation Solution

The method involves selecting a limited number of specific interferometric phases, fewer than 10, to maximize contrast between different wavelengths, allowing for rapid chemical and optical imaging by measuring signals at these phases, thereby reducing the time required to acquire full hyperspectral images from hours to minutes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional s-SNOM uses broadband sources with extensive interferometric measurements at multiple phases, then complete hyperspectral images can be acquired, but the acquisition time becomes impractically long

Engineering Contradiction:
Improvespectral resolutionVSAvoidacquisition time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies partial action by measuring interferometric signals at only a limited number of specific phases (less than 10) rather than performing complete interferometric measurements at all phases. This selective measurement approach captures sufficient spectral information to reconstruct chemical and optical images while dramatically reducing acquisition time from hours to minutes.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent changes the measurement parameter from continuous phase scanning to discrete phase sampling. By selecting specific phases that maximize contrast between different wavelengths and chemical species, the method transforms the measurement approach to achieve both speed and spectral resolution simultaneously.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If a limited number of reference phases is used to reduce acquisition time, then high-speed imaging is achieved, but sufficient spectral information must still be captured

Engineering Contradiction:
Improveimaging speedVSAvoidspectral information
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent performs preliminary action by pre-selecting optimal reference phases that maximize contrast between different wavelengths and chemical species. This pre-selection ensures that the limited number of measurements captures the most informative spectral features, preventing loss of critical spectral information while enabling high-speed imaging.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent substitutes the mechanical phase scanning system with a computational approach. Instead of physically scanning through all phases, the method uses mathematical reconstruction algorithms to derive complete spectral information from measurements at limited phases, replacing mechanical motion with computational processing.

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

This approach enables the construction of high-speed chemical and optical images with a broadband source, significantly reducing acquisition time while maintaining high signal quality, allowing for efficient mapping of optical properties and chemical distributions across a sample.

Implementation Method 1

illumination of a sample with a beam of light from at least one broadband radiation source

Methodology Applied
Scientific EffectBroadband radiation emission: Thermal Radiation

Implementation Method 2

The resolution improvement comes from a local enhancement of the incident radiation field due to the sharp tip. The enhanced radiation field interacts with the sample and then scatters radiation into the far field.

Methodology Applied
Scientific EffectNear-field enhancement: Scattering

Implementation Method 3

interfering a reference beam with at least one of (i) light scattered from the region of tip/sample interaction and (ii) light incident on the tip/sample interaction region

Methodology Applied
Scientific EffectOptical interference: Interference

Data Source

PatentEP3293525B1Method and apparatus for chemical and optical imaging with a broadband source
Publication Date: 2024.09.25 BRUKER NANO INC
  • EP3293525B1 patent drawingFigure 1
  • EP3293525B1 patent drawingFigure 2A~2B
  • EP3293525B1 patent drawingFigure 2C~2D

AI summary

Systems and methods that enable both spectroscopy and rapid chemical and/or optical imaging using a broadband light source. Broadband light sources may be advantageous for spectroscopy as they simultaneously illuminate a sample with a plurality of wavelengths and use interferometric techniques to determine a material response as a function of wavelength (or equivalently wavenumber). Some embodiments may enable the same radiation sources to be used to efficiently map the spatial distribution of chemical species or optical property variations. This may be achieved via selection of specific optical phase delays within an interferometer that are selected to maximize the contrast between different absorption bands or resonances within the sample. By optimally selecting specific interferometer phases it may be possible to construct images that substantially represent the material response to a specific wavelength excitation, without the necessity to obtain entire spectra at each sample location. This can provide orders of magnitude improvements in the measurement speed for required with a broadband source to provide compositional/optical property mapping.