Spatiotemporal Beamlet Multiplexing for High-Speed Volumetric Sampling
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Solution Overview
Problem
Current two-photon scanning microscopy systems are limited by the tradeoffs among imaging speed, spatial resolution, signal-to-noise ratio, and recording volume, preventing effective volumetric imaging of neuronal activity across the entire cortical surface at physiological rates.
Innovation Solution
The implementation of a spatiotemporal multiplexing module that splits laser pulses into multiple beamlets, each delayed and focused to different axial or lateral positions, allowing simultaneous volumetric scanning without the need for axial scanning, and dynamically adjusts power based on sample depth to maintain signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a focused beam is scanned to form an image in two-photon microscopy, then spatial resolution is improved, but imaging speed and volumetric field-of-view are limited
Solution Approach 1:
The patent segments a single laser beam into multiple beamlets using diffractive optical elements. Each beamlet can be independently focused to different axial planes, enabling parallel imaging across multiple depths simultaneously. This segmentation transforms a sequential scanning approach into a parallel volumetric imaging system, resolving the contradiction between spatial resolution and imaging speed.
Solution Approach 2:
The patent extends imaging from 2D lateral scanning to 3D volumetric imaging by introducing axial dimension multiplexing. Multiple beamlets are focused to different axial planes (z-positions) within the sample, creating a volumetric field-of-view that captures neuronal activity across depth simultaneously. This dimensional extension allows high-speed volumetric imaging without sacrificing spatial resolution in any dimension.
2Measurement precision
If laser power is increased to improve signal-to-noise ratio at depth, then signal quality is improved, but heat penalty and tissue damage increase
Solution Approach 1:
The patent segments the total laser power across multiple beamlets, with each beamlet delivering optimized power to its specific axial plane. This segmentation allows the system to achieve adequate signal-to-noise ratio at depth by concentrating power where needed while distributing the thermal load across multiple lower-power beamlets, reducing overall heat penalty compared to using a single high-power beam.
Solution Approach 2:
The patent applies local quality optimization by independently controlling the power and focal position of each beamlet. Beamlets targeting deeper planes can be assigned higher power to overcome scattering and absorption, while beamlets at shallower depths use lower power. This localized power optimization maintains signal quality throughout the volume while minimizing unnecessary heating in regions where less power is required.
3Volume of stationary object
If volumetric field-of-view is increased to record across the entire cortex, then recording coverage is improved, but imaging speed and resolution are compromised
Solution Approach 1:
The patent segments the volumetric field-of-view into multiple axial planes, each illuminated by a dedicated beamlet. This segmentation enables simultaneous recording across the entire cortical depth without requiring sequential scanning through z-positions. The system achieves large volumetric coverage at high speeds by parallelizing the imaging process across multiple depth planes, resolving the contradiction between field-of-view size and recording speed.
4Length of stationary object
If axial scanning is performed to achieve volumetric imaging, then depth coverage is improved, but imaging speed is reduced
Solution Approach 1:
The patent extracts the axial scanning function by using diffractive optical elements to directly generate multiple beamlets focused at different axial planes. This eliminates the need for mechanical or galvanometric axial scanning mechanisms. The axial depth coverage is achieved through optical path differentiation rather than physical scanning, thereby maintaining high imaging speeds while obtaining full volumetric data.
Solution Approach 2:
The patent replaces mechanical axial scanning systems with a static diffractive optical element that optically generates multiple axial foci. This substitution eliminates moving parts and scanning time, allowing simultaneous illumination of multiple depth planes. The mechanical scanning process is replaced by an optical field transformation that achieves the same depth coverage instantaneously, resolving the speed-coverage tradeoff.
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-speed, high-resolution volumetric imaging of neuronal activity across large volumes with minimal heat penalty, achieving near-simultaneous recording of thousands of neurons at cellular resolution and preserving signal-to-noise ratio throughout the depth of the sample.
Implementation Method 1
splitting each laser pulse into a plurality of beamlets
Implementation Method 2
changing a divergence of each subsequent beamlet of the plurality of beamlets associated with each respective laser pulse to introduce a distinguishing feature between each beamlet
Implementation Method 3
cause each beamlet to focus on a different axial plane or lateral position of the sample
Implementation Method 4
Two-photon (2p) scanning microscopy paired with genetically encoded Calcium indicators
Implementation Method 5
recording activity, particularly at depth, in scattering brain tissue
Data Source
Figure 1A(a)~1A(b)
Figure 1B~1C(d)
Figure 1D
AI summary
A multiplexing module provided herein is configured to perform operations of receiving a plurality of laser pulses from a pulsed laser source; splitting each laser pulse into a plurality of beamlets; introducing a delay between each adjacent beamlet of the plurality of beamlets, such that the plurality of beamlets associated with a respective laser pulse of the plurality of laser pulses is distributed equally across a pulse repetition period associated with the pulsed laser source; changing a divergence of each subsequent beamlet of the plurality of beamlets associated with each respective laser pulse to introduce a distinguishing feature between each beamlet of the plurality of beamlet to cause each beamlet to focus on a different axial plane or lateral position of the sample; and outputting the plurality of beamlets associated with each respective laser pulse.