Snapshot Optical Tomography Using Microlens Array Multiplexing
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Solution Overview
Problem
Digital holographic tomography faces challenges with low imaging throughput due to the need for multiple projection images and poor axial resolution caused by insufficient scattering data collection, leading to motion artifacts and missing-angle artefacts, which increase system complexity and cost, limiting its use in research and development.
Innovation Solution
The implementation of snapshot optical tomography using angular multiplexing of illumination and defocused light-field imaging, allowing for the recording of multiple projection images in a single instance and reconstruction of three-dimensional refractive index maps without motion or missing-angle artefacts, utilizing a micro-lens array and camera system to capture images at different angles simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple projection images are collected at different angles using scanning mechanisms, then measurement precision of three-dimensional refractive index is improved, but imaging throughput deteriorates and system complexity increases
Solution Approach 1:
The patent divides the single illumination beam into multiple angular components using a microlens array, creating a bundle of beams that illuminate the sample at different angles simultaneously. This segmentation allows parallel acquisition of multiple projection images without mechanical scanning, thereby improving imaging throughput while maintaining measurement precision.
Solution Approach 2:
The patent transitions from temporal/m mechanical scanning (sequential angle acquisition) to spatial multiplexing (simultaneous angular acquisition). By using a microlens array to create angularly dispersed beams in the spatial domain, the system captures multiple projection images at different angles simultaneously, eliminating the trade-off between precision and throughput.
2Measurement precision
If multiple projection images are collected at different angles, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces mechanical scanning mechanisms (galvanometer-mounted mirrors or rotating stages) with an optical field-based approach. A microlens array is used to generate multiple angular beams through optical field manipulation, eliminating moving parts and reducing device complexity while maintaining the ability to collect data at multiple angles.
Solution Approach 2:
The microlens array serves multiple functions simultaneously: it acts as an angular multiplexer to create multiple illumination angles, a beam splitter to distribute light, and a parallel processing element to enable simultaneous acquisition. This multi-functionality reduces the need for separate scanning mechanisms and other auxiliary components.
3Device complexity
If insufficient scattering data is collected, then system complexity is reduced, but axial resolution and measurement accuracy deteriorate due to missing-angle artifacts
Solution Approach 1:
The microlens array segments the illumination into multiple angular components, ensuring that scattering data is collected across a broad angular range simultaneously. This segmentation provides comprehensive sampling of the scattering field, improving axial resolution and reducing missing-angle artifacts while maintaining manageable system complexity.
Solution Approach 2:
The patent employs local quality by using a microlens array where each lenslet independently contributes to a specific angular component. This allows localized optimization of angular coverage and scattering data collection, ensuring adequate sampling in all directions to improve axial resolution without requiring uniform complex systems throughout.
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 high-speed three-dimensional imaging of flowing cells and reduces system complexity, providing accurate refractive index maps with improved axial resolution and eliminating artefacts, thus enhancing imaging throughput and usability in research applications.
Implementation Method 1
angular multiplexing of illumination and light field imaging
Implementation Method 2
recording the complex-valued light fields, called projection images, at different angles of illumination
Implementation Method 3
applying a tomographic reconstruction algorithm, the complex refractive index distribution in three dimensions can be measured
Data Source
AI summary
This disclosure discloses a method of creating a three-dimensional image of a sample using snapshot optical tomography. The method includes generating a plurality of beams incident on the sample simultaneously, acquiring a field image at a plane not conjugate to the sample plane using off-axis digital holography, extracting amplitude data and phase data for the field image, restoring the sharpness by backpropagating the field image using the extracted amplitude and phase data, acquiring a background image, extracting amplitude data and phase data for the background image, and reconstructing a three-dimensional image of the sample with the backpropagated field image and the background image. The method also includes arranging more than one imaging chains to remove the missing angle artefacts in optical tomography. Also disclosed are systems for performing the method.