Laser-Based Fourier Ptychographic Imaging Resolution
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Solution Overview
Problem
Conventional imaging systems face limitations in achieving high-resolution imaging due to geometric aberrations and spatial-bandwidth product constraints, particularly in microscopy applications, where existing techniques like interferometric synthetic aperture methods suffer from noise, mechanical alignment issues, and reduced spatial-bandwidth product.
Innovation Solution
The development of laser-based Fourier ptychographic (LFP) imaging systems that utilize an angle direction device to direct laser light at varying angles, combined with an optical system and light detector to acquire and process intensity images, enabling high-resolution image reconstruction through differential phase contrast deconvolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging systems use standard lenses to focus light onto the image sensor, then the system structure is simple, but the resolution is fundamentally limited by geometric aberrations in the lens
Solution Approach 1:
The patent segments the illumination into multiple discrete angles using a discrete angular illumination system. Instead of using a single continuous illumination source, the system divides the illumination into distinct angular components, each providing information about different spatial frequencies of the sample. This segmentation allows the system to overcome the resolution limits of conventional single-angle imaging by combining information from multiple angular perspectives.
Solution Approach 2:
The patent introduces angular dimension to the imaging process. By illuminating the sample at multiple discrete angles and capturing the modulated transmission, the system adds an angular degree of freedom to the traditional spatial imaging. This dimensional expansion enables recovery of high-frequency spatial information that would otherwise be lost, effectively breaking the diffraction limit without requiring more complex lens systems.
2Measurement precision
If interferometric synthetic aperture techniques use highly coherent light sources to increase spatial-bandwidth product, then the resolution improves, but coherent noise sources such as speckle noise and fixed pattern noise increase
Solution Approach 1:
The patent changes the coherence parameter of the light source by using a laser with controlled coherence properties. The system adjusts the illumination parameters to achieve the right balance between coherence for resolution improvement and incoherence to minimize speckle noise. By optimizing the coherence length and using appropriate illumination conditions, the system achieves high spatial-bandwidth product while minimizing coherent noise artifacts.
Solution Approach 2:
The patent converts the potentially harmful effect of laser coherence into a beneficial one. While laser coherence can cause speckle noise, the system uses this coherence to achieve the necessary interference patterns for high-resolution imaging. By carefully controlling the illumination geometry and using computational methods to process the images, the system extracts useful high-frequency information while suppressing the harmful noise components.
3Ease of manufacture
If LED-based illumination is used in Fourier ptychographic microscopy, then the system is simpler and less expensive, but the image acquisition time is longer
Solution Approach 1:
The patent changes the illumination source parameter from LED to laser. This parameter change enables significantly faster image acquisition by utilizing the higher brightness and coherence properties of laser light. The laser illumination allows for shorter exposure times while maintaining sufficient signal quality, thereby increasing the frame rate and reducing the total acquisition time for high-resolution images.
Solution Approach 2:
The patent uses computational methods to reconstruct the image from the modulated transmission measurements. Instead of requiring direct high-frequency information capture, the system uses algorithms to synthesize the high-resolution image from the angularly multiplexed data. This computational copying approach enables fast acquisition while achieving resolution beyond what would be possible with direct imaging methods.
4Measurement precision
If mechanical scanning is used to rotate the sample in interferometric imaging systems, then the spatial-bandwidth product improves, but precise optical alignments and mechanical control at sub-micron level are required
Solution Approach 1:
The patent replaces mechanical scanning and alignment systems with a discrete angular illumination approach. Instead of physically rotating the sample or adjusting mechanical components to achieve different viewing angles, the system uses a fixed optical setup with discrete angular illumination sources. This substitution eliminates the need for precise mechanical control and real-time alignment while still achieving the desired spatial-bandwidth product through computational image synthesis.
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
LFP systems achieve faster image acquisition times, improved resolution, and enhanced imaging capabilities compared to LED-based systems, allowing for high-resolution imaging in a short duration and effectively mitigating noise artifacts.
Implementation Method 1
direct laser light from a laser light source(s) to a sample plane generally at a specimen surface
Implementation Method 2
laser-based Fourier ptychographic (LFP) imaging systems
Implementation Method 3
The collection element is configured to receive light issuing from a specimen
Implementation Method 4
The focusing element is configured to focus light propagated from the collection element to the light detector
Implementation Method 5
The light detector is configured to receive light focused by the focusing element and to acquire a plurality of raw intensity images
Implementation Method 6
iteratively updating overlapping regions in the Fourier domain with the plurality of intensity images acquired by the light detector to generate a high resolution image
Implementation Method 7
filtering out low spatial frequency artifacts associated laser light by using a differential phase contrast deconvolution procedure
Data Source
AI summary
Certain embodiments pertain to laser-based Fourier ptychographic (LFP) imaging systems, angle direction devices used in the LFP imaging systems, optical switches used in the LFP imaging systems, and LFP imaging methods. The LFP systems include an angle direction device for directing laser light to a sample plane at a plurality of illumination angles at different sample times. The LFP systems also include an optical system and a light detector. The optical system receives light issuing from the sample being imaged and propagates and focuses the light to the light detector acquiring raw intensity images.