Quantitative Phase Tomography Linear Scanning Apparatus

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Solution Overview

Problem

Current methods for quantitative refractive index tomography rely on rotations of the sample or illumination beam, which are mechanically complex and prone to inaccuracies, and typically assume plane wave illumination, limiting the efficiency and resolution of three-dimensional imaging.

Innovation Solution

The apparatus employs a specially shaped illumination with a structured wavefront and linear scanning of the specimen, allowing for direct acquisition of angular information without rotation, using a projection formalism or diffraction theory to reconstruct the three-dimensional distribution of refractive indices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If rotation of sample or illumination beam is used to acquire angular information, then tomographic data can be collected, but mechanical complexity increases and measurement precision decreases

Engineering Contradiction:
Improveangular information accuracyVSAvoidmechanical rotation system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical rotation system with a static illumination system that uses a shaped wavefront (e.g., annular, conical, or multi-directional beam patterns) to provide angular diversity. The illuminated sample is scanned linearly through the shaped beam, acquiring angular information optically rather than mechanically, thereby eliminating complex rotation mechanisms while maintaining or improving measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the illumination parameter from conventional plane waves to specially shaped wavefronts with controlled angular distributions. By engineering the wavefront shape (e.g., using spatial light modulators or shaped aperture masks), the system directly provides the required angular information without mechanical movement, transforming the illumination geometry to match the tomographic reconstruction requirements.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If plane wave illumination is used, then standard reconstruction methods can be applied, but imaging efficiency and resolution are limited

Engineering Contradiction:
Improveimaging efficiencyVSAvoidimage resolution
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the illumination parameter from conventional plane waves to specially shaped wavefronts (e.g., annular, conical, or multi-directional beams) that directly provide the angular diversity needed for tomography. This transformation of the illumination geometry enables faster data acquisition through linear scanning while improving resolution by capturing higher spatial frequency information through the engineered wavefront shapes.

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 simplifies the data acquisition process, improves mechanical stability, and enables high-resolution three-dimensional imaging by directly obtaining pluri-angle views through linear specimen displacement, overcoming the limitations of traditional methods.

Implementation Method 1

The apparatus relies on a specially shaped illumination, which provides straightforwardly an angular distribution in the illumination of the specimen

Methodology Applied
Scientific EffectStructured wavefront illumination:

Implementation Method 2

coherent and non-coherent detection of beams scattered by a specimen

Methodology Applied
Scientific EffectCoherent detection:

Implementation Method 3

detection of beams scattered by a specimen

Methodology Applied
Scientific EffectScattering: Scattering

Implementation Method 4

employ more general formalisms considering the diffraction theory, in which case a measurement of the full information of the wave (amplitude and phase) is required for tomographic reconstruction

Methodology Applied
Scientific EffectDiffraction: Diffraction

Data Source

PatentEP2736403B1Apparatus for quantitative phase tomography through linear scanning with coherent and non-coherent detection
Publication Date: 2022.05.18 ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE (EPFL)
  • EP2736403B1 patent drawingFigure 1a
  • EP2736403B1 patent drawingFigure 1b
  • EP2736403B1 patent drawingFigure 1c

AI summary

The disclosed invention describes a new apparatus performing a new data acquisition for quantitative refractive index tomography. It is based on a linear scanning of the specimen, opposed to the classical approaches based on rotations of either the sample or the illumination beam, which are based on the illumination with plane waves, which orientation is successively modified in order to acquire angular information. On the contrary, the inventive apparatus and method rely on a specially shaped illumination, which provides straightforwardly an angular distribution in the illumination of the specimen. The specimen can thus be linearly scanned in the object plane in order to acquire the data set enabling tomographic reconstruction, where the different positions directly possess the information on various angles for the incoming wave vectors.