Optical Tomography Pseudo-Projection via Focal Plane Scanning
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Solution Overview
Problem
Existing optical tomography methods face challenges in achieving high-resolution three-dimensional imaging of thick specimens due to diffraction and scattering issues, leading to low throughput, spatial resolution limitations, and undesirable spurious signals from out-of-focus light.
Innovation Solution
The method involves continuously scanning the focal plane of an optical imaging system through the specimen's thickness during a single detector exposure, generating shadowgrams from multiple perspectives using point-source or pseudoprojection techniques, which reduces scattered light and enhances signal-to-noise for high-quality three-dimensional reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical tomography methods are used to image thick specimens, then three-dimensional reconstruction can be achieved, but diffraction and scattering cause reduced spatial resolution and spurious signals from out-of-focus light
Solution Approach 1:
The patent employs dynamic scanning of the focal plane through the specimen thickness during a single detector exposure, rather than using static imaging. This continuous scanning approach allows the system to collect projection data from multiple focal depths simultaneously, improving spatial resolution while reducing out-of-focus light artifacts through temporal integration during the scan.
Solution Approach 2:
The system changes the focal plane position parameter continuously during data acquisition, scanning through the specimen thickness. This parameter change enables the optical system to maintain focus at different depths throughout the exposure period, thereby achieving high-resolution 3D imaging without the blurring caused by static out-of-focus light.
2Measurement precision
If multiple shadowgrams are acquired from different perspectives to improve three-dimensional reconstruction quality, then measurement precision improves, but data acquisition time increases
Solution Approach 1:
The patent implements continuous data acquisition by scanning the focal plane throughout the entire detector exposure period, rather than acquiring discrete images sequentially. This continuous scanning allows multiple projection perspectives to be collected simultaneously within a single exposure time, maintaining high reconstruction quality while minimizing data acquisition time.
Solution Approach 2:
The system performs preliminary scanning of the focal plane to map the specimen thickness and optical properties before the actual data acquisition. This preliminary action allows optimization of the scanning range and speed, enabling faster subsequent data acquisition while ensuring complete coverage of the specimen volume for high-quality reconstruction.
3Productivity
If the focal plane is scanned through the specimen thickness during a single detector exposure, then data acquisition speed improves and out-of-focus light is reduced, but system complexity increases
Solution Approach 1:
The patent replaces mechanical scanning of the specimen or detector with scanning of the focal plane through optical means, such as adjusting the lens focal position or using acoustic/optical focusing mechanisms. This substitution reduces mechanical complexity and inertia, enabling faster scanning speeds while maintaining the ability to collect projection data from multiple depths during a single exposure.
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 results in faster data acquisition with higher signal-to-noise ratios and improved spatial resolution, reducing blurring and motion artifacts, while allowing for precise measurement of density and fluorescence distributions within microscopic volumes.
Implementation Method 1
a shadowgram (a.k.a. projection) being a measure of light attenuation along a set of ray paths through the specimen
Implementation Method 2
in high-resolution optical tomography, the illumination photon wavelength(s) may be on the order of the desired spatial resolution and object feature size, a projection image obtained in a manner analogous to the methods of x-ray tomography will be obscured due to diffraction of the incident light by the specimen features
Implementation Method 3
Because photons are scattered or deflected from their straight-line paths, particularly in passing through the object, the detector elements may receive photons from unknown locations within the object
Data Source
AI summary
A system for optical imaging of a thick specimen that permits rapid acquisition of data necessary for tomographic reconstruction of the three-dimensional (3D) image. One method involves the scanning of the focal plane of an imaging system and integrating the range of focal planes onto a detector. The focal plane of an optical imaging system is scanned along the axis perpendicular to said plane through the thickness of a specimen during a single detector exposure. Secondly, methods for reducing light scatter when using illumination point sources are presented. Both approaches yield shadowgrams. This process is repeated from multiple perspectives, either in series using a single illumination/detection subsystem, or in parallel using several illumination/detection subsystems. A set of pseudo-projections is generated, which are input to a three dimensional tomographic image reconstruction algorithm.