Frequency-Domain Modulation for Low-Noise Super-Resolution Microscopy
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Solution Overview
Problem
Conventional far-field optical microscopy is limited by the diffraction limit, and STED microscopy suffers from background noise and photobleaching, which reduces sample observability and imaging resolution.
Innovation Solution
A device utilizing frequency-domain modulation with a laser device, glan prism, electro-optic modulator, 0˜2π vortex phase plate, quarter-wave plate, dichroic mirror, galvanometer scanner, and lock-in amplifier to remove background noise and improve resolution by modulating laser beams with different frequencies and polarizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-power depletion beam is used to improve resolution in STED microscopy, then imaging resolution is improved, but photobleaching and photodamage increase significantly
Solution Approach 1:
The patent applies periodic modulation to the depletion beam using an electro-optic modulator, switching between high-power and low-power states at specific frequencies. This periodic action allows the system to achieve high resolution during high-power phases while reducing photodamage during low-power phases, effectively resolving the contradiction between resolution and sample damage.
Solution Approach 2:
The patent dynamically changes the power parameter of the depletion beam through electro-optic modulation, transitioning between different power states. This parameter change enables the system to optimize resolution when needed while minimizing photodamage during other periods, directly addressing the technical contradiction.
2Manufacturing precision
If high-power depletion beam is used to improve resolution in STED microscopy, then imaging resolution is improved, but background noise from secondary excitation increases
Solution Approach 1:
The patent uses periodic modulation at frequency f1 for the depletion beam and f2 for the excitation beam. By carefully selecting these frequencies and using lock-in detection, the system can distinguish the desired signal from background noise generated during high-power phases, maintaining high resolution while suppressing background interference.
Solution Approach 2:
The patent introduces frequency modulation as an intermediary mechanism. By encoding the depletion signal at a specific frequency and using lock-in amplification, the system can extract the useful signal while filtering out background noise, thus resolving the contradiction between resolution and background noise.
3Object-generated harmful factors
If frequency-domain modulation is applied to remove background noise, then background noise is reduced, but device complexity increases
Solution Approach 1:
The patent introduces frequency modulation as an intermediary mechanism. By encoding the depletion signal at a specific frequency and using lock-in amplification, the system can extract the useful signal while filtering out background noise, thus resolving the contradiction between resolution and background noise.
4Manufacturing precision
If frequency-domain modulation with dual-frequency modulation is used to remove background noise, then imaging resolution is improved, but device complexity increases
Solution Approach 1:
The patent employs a lock-in amplifier that can perform dual-frequency demodulation, making this single device capable of handling both modulation frequencies. This multi-functionality approach reduces overall system complexity compared to using separate detection systems for each frequency, while still achieving the resolution improvement through background noise suppression.
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
Effectively removes secondary excitation fluorescence and incomplete depletion background signals, enabling fast imaging with high resolution and reduced photobleaching.
Implementation Method 1
an electro-optic modulator configured to modulate intensities of two beams of the line-polarized light corresponding to the high-power laser and the low-power laser
Implementation Method 2
a glan prism configured to change polarization states of a laser beam emitted by the laser device to obtain line-polarized light
Implementation Method 3
a quarter-wave plate configured to change polarization states of the two beams of the line-polarized light to obtain two beams of right-handed circularly polarized light
Implementation Method 4
a 0˜2π vortex phase plate configured to perform phase modulation of the high-power laser
Implementation Method 5
a lock-in amplifier configured to demodulate received signal light at a specific frequency to obtain an image at a corresponding scanning position
Implementation Method 6
a dichroic mirror configured to combine the low-power laser and the high-power laser with phase modulation into a single beam
Data Source
AI summary
The present disclosure relates to a method and device for removing background noise in microscopic imaging based on frequency-domain modulation. The method includes irradiating a surface of a sample to be measured by simultaneously irradiating the surface of the sample by utilizing two beams from two laser devices. One of the two beams passes through a 0˜2π vortex phase plate and then focuses on the sample to be measured to form a high-energy hollow spot, and the other of the two beams focuses on the sample to be measured to form a low-energy solid spot. The method further includes modulating the two beams in time-domain simultaneously using an electro-optic modulator and demodulating signal light at different frequencies using a lock-in amplifier, then removing the background noise by a differential process to realize a high signal-to-noise ratio super-resolution image.