Optical Pulse Generator for Deep Tissue Microscopy
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Solution Overview
Problem
Current two-photon microscopy techniques are limited in penetration depth and field of view, particularly in scattering tissues like the intact mouse brain, making it difficult to achieve high spatial and temporal resolution imaging over large areas.
Innovation Solution
The development of a Dual Excitation with adaptive Excitation Polygon-scanning multiphoton microscope (DEEPscope) that utilizes a ring resonator, polarizing beamsplitter, and polarization optics to generate and manipulate optical beamlets, enabling deep penetration and large field of view imaging through adaptive excitation and optimized point spread function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional two-photon microscopy is used, then imaging is achieved, but penetration depth is limited to 600-700 μm in intact mouse brain
Solution Approach 1:
The patent changes the excitation wavelength parameter from conventional two-photon wavelengths to three-photon excitation using 1300 nm laser pulses. This parameter change enables deeper penetration into scattering tissues while maintaining imaging capability, resolving the contradiction between penetration depth and imaging resolution.
Solution Approach 2:
The patent employs periodic pulse excitation with specific pulse durations (1-100 ps) and repetition rates (100 kHz - 10 MHz). This periodic action enables efficient energy delivery to achieve deep penetration while maintaining temporal resolution for high-speed imaging of calcium transients.
2Area of stationary object
If large field of view imaging is achieved, then spatial coverage is improved, but spatial and temporal resolution deteriorate
Solution Approach 1:
The patent segments the imaging process by using multiple beamlets generated through a ring resonator with polarizing beamsplitters. Each beamlet can be independently controlled and timed, allowing the system to achieve both large field of view coverage and high spatial resolution through coordinated scanning of multiple focal points.
Solution Approach 2:
The patent introduces temporal dimension control through variable pulse delays between beamlets. By controlling the time delay between excitation pulses, the system achieves super-resolution capability while maintaining large field of view, effectively adding a temporal dimension to spatial imaging.
3Measurement precision
If high temporal resolution imaging is achieved, then detection fidelity is improved, but imaging speed and productivity deteriorate
Solution Approach 1:
The patent implements continuous excitation through rapid sequential pulsing of multiple beamlets with high repetition rates (100 kHz - 10 MHz). This continuous action maintains high temporal resolution for detecting fast calcium transients while improving imaging speed through efficient use of the laser pulse train.
Solution Approach 2:
The patent uses periodic pulse excitation with optimized pulse durations and repetition rates to achieve high temporal resolution. The periodic nature of the excitation allows for efficient data collection at high speeds while maintaining the ability to resolve fast biological events like action potentials.
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
DEEPscope achieves high-resolution imaging with a 3.5 mm diameter field of view deep in scattering tissues, reducing the risk of misattributing calcium transients and improving detection fidelity by doubling the fluorescence signal and spatial and temporal resolution compared to conventional methods.
Implementation Method 1
a polarizing beamsplitter that (i) is between a first mirror and a final mirror of the plurality of mirrors, (ii) outputs a first polarization component of an incident optical signal as a non-delayed output beamlet propagating along a non-delayed output-beam path, (iii) outputs a second polarization component of the incident optical signal onto a first optical path of a plurality of distinct optical paths as a first delayed-beamlet propagating toward the first mirror
Implementation Method 2
a ring resonator including a plurality of mirrors that at least in part define a plurality of distinct optical paths within the ring resonator
Data Source
AI summary
An optical beamlet-array generator includes a ring resonator, a polarizing beamsplitter and a polarization optic. The ring resonator includes a plurality of mirrors that in part define a plurality of distinct optical paths within the ring resonator. The polarizing beamsplitter (i) is between a first mirror and a final mirror, (ii) outputs a first polarization component of an incident optical signal as a non-delayed output beamlet propagating along a non-delayed output-beam path, (iii) outputs a second polarization component of the incident optical signal onto a first optical path as a first delayed-beamlet propagating toward the first mirror. The beamsplitter reflects the transverse electric polarization component of the first delayed-beamlet out of the first optical path as a delayed-output beamlet that propagates along a delayed output-beam path that is offset from the non-delayed output-beam path. The polarization optic is on the first optical path and modifies the first delayed-beamlet's polarization state.