3D Imaging Transparent Biological Objects via Optical Tomography

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Solution Overview

Problem

Existing full-field optical tomography techniques struggle to effectively image highly transparent biological objects, such as cells or thin tissue structures, due to the overwhelming signal reflection from transparent substrates like glass or plastic, which masks the weaker biological signals by three to five orders of magnitude.

Innovation Solution

A novel method utilizing spatially incoherent light illumination and phase variation of scattered beams, combined with a Gouy phase shift, allows for three-dimensional imaging of transparent biological objects by moving the microscope objective relative to the sample to acquire interferometric signals at different focal planes, enabling the extraction of specific biological information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If full-field optical tomography is used to image transparent biological objects, then three-dimensional imaging capability is achieved, but substrate reflection overwhelms the biological signal by three to five orders of magnitude

Engineering Contradiction:
Improveimaging capabilityVSAvoidsubstrate reflection
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The imaging process is segmented into multiple focal planes along the optical axis. By acquiring interferometric signals at different depths and processing them separately, the method isolates biological signals from substrate reflections, as each focal plane captures information from a specific depth range while rejecting out-of-focus substrate signals.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The method transitions from two-dimensional imaging to three-dimensional imaging by adding the axial dimension (depth) through focal plane scanning. This dimensional expansion allows discrimination between biological objects and substrate based on their different axial positions, effectively separating the weak biological signals from the strong substrate reflections.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If conventional OCT techniques are used, then imaging speed is reduced, but if full-field OCT is used, then imaging speed improves while maintaining resolution

Engineering Contradiction:
Improveimaging speedVSAvoidresolution
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The method merges the advantages of full-field interferometry (fast parallel acquisition) with optical sectioning capabilities. By combining broadband light interference microscopy with full-field detection, the system achieves both high imaging speed and micrometer-scale resolution simultaneously, overcoming the trade-off present in conventional techniques.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If fluorescence microscopy is used to achieve submicron imaging, then resolution is improved, but genetic or chemical modification of the sample is required

Engineering Contradiction:
ImproveresolutionVSAvoidsample preparation
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The method exploits the intrinsic optical properties of biological objects themselves for imaging, without requiring external labels, dyes, or genetic modifications. The biological structures serve their own imaging function through their natural light scattering and interference properties, eliminating the need for complex sample preparation procedures.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The method changes the imaging parameter from detecting fluorescent emission (which requires modification) to detecting scattered and interfered light in transmission mode. This parameter change allows imaging of transparent biological objects using their inherent optical characteristics rather than requiring them to be made fluorescent.

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

Enables high-contrast, three-dimensional imaging of transparent biological objects with excellent resolution and ease, overcoming the challenge of substrate interference and providing detailed structural and biochemical information.

Implementation Method 1

acquiring, by means of a two-dimensional acquisition device comprising a plurality of elementary detectors arranged in a detection plane, a plurality of two-dimensional interferometric signals resulting from optical interference between the illumination beam incident on said object field and a beam scattered by said object field

Methodology Applied
Scientific EffectOptical interference: Interference

Implementation Method 2

positioning the sample in the vicinity of an object focal plane of a microscope objective

Methodology Applied
Scientific EffectOptical focusing: Focusing

Implementation Method 3

phase variation of scattered beams, combined with a Gouy phase shift, allows for three-dimensional imaging

Methodology Applied
Scientific EffectGouy phase shift: Phase Modulation

Implementation Method 4

a beam scattered by said object field

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP4348167B1Methods and systems for three-dimensional imaging of a transparent biological object in a biological sample by full-field optical tomography
Publication Date: 2025.07.02 CENT NAT DE LA RECH SCI (C N R S)
  • EP4348167B1 patent drawingFigure 1A~1B
  • EP4348167B1 patent drawingFigure 2A~2B
  • EP4348167B1 patent drawingFigure 3A~3B

AI summary

The present description relates to a three-dimensional imaging system (100) comprising a light source (110) configured to emit a beam of spatially incoherent light, having a given central length, configured to illuminate a biological sample (10) being transmitted; an optical imaging system (120) comprising a microscope lens (121) with a given object focal plane (125) near which the sample (10) is positioned; means for axially moving the microscope lens relative to the sample; a two-dimensional acquisition device (140) comprising a plurality of elementary detectors arranged in a detection plane (141) optically conjugate with the object focal plane and a processing unit (150). For each section of a biological object of the sample, a plurality of two-dimensional interferometric signals resulting from optical interference between the illumination beam and a beam scattered by an object field of the section are acquired and at least a first image is calculated from the plurality of two-dimensional interferometric signals.