Programmable Annular LED Illumination for Quantitative Phase Microscopy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional quantitative phase imaging methods face limitations in achieving high imaging resolution and robust phase contrast due to the trade-off between imaging resolution and phase contrast, particularly with coherent illumination, which requires complex setups and is sensitive to environmental conditions.
Innovation Solution
A programmable annular LED illumination-based method that derives and applies the optical transfer function for partially coherent imaging systems, utilizing a discrete annular LED illumination pattern to enhance phase transfer function robustness and achieve twice the objective lens resolution, while being compatible with traditional microscopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Kohler illumination is used in quantitative phase imaging, then phase contrast is improved, but imaging resolution is limited to 70%-80% of the objective lens numerical aperture
Solution Approach 1:
The illumination source is segmented into multiple discrete LED elements arranged in an annular pattern, allowing independent control of different illumination angles. This segmentation enables the system to simultaneously capture multiple spatial frequencies that would otherwise require separate measurements, thereby achieving twice the resolution of the objective lens while maintaining phase contrast.
Solution Approach 2:
The patent transitions from traditional planar Kohler illumination to three-dimensional annular illumination in the spatial frequency domain. By illuminating from multiple angles simultaneously in the annular configuration, the system accesses higher spatial frequencies beyond the objective lens numerical aperture limit, effectively extending the resolution boundary while preserving phase contrast information.
2Illumination intensity
If coherent illumination is used to achieve maximum phase contrast, then phase contrast is improved, but the system becomes sensitive to environmental conditions and requires complex interference devices
Solution Approach 1:
The patent extracts the essential function of phase contrast enhancement from complex interference devices by using annular LED illumination combined with the transport of intensity equation. This approach separates phase information extraction from interference patterns, eliminating the need for reference beams and complex interferometric setups while maintaining robust phase contrast.
Solution Approach 2:
The patent replaces mechanical/optical interference-based phase contrast methods with a computational approach based on the transport of intensity equation. By substituting physical interference devices with mathematical phase retrieval algorithms, the system achieves phase contrast without sensitivity to environmental vibrations or complex optical path requirements.
3Measurement precision
If higher illumination numerical aperture is used to improve imaging resolution, then imaging resolution is improved, but phase contrast of captured intensity images becomes weak
Solution Approach 1:
The patent employs iterative phase retrieval algorithms that use feedback from multiple intensity measurements at different axial positions to reconstruct phase information. This feedback mechanism allows the system to recover phase contrast even when using high numerical aperture illumination that would otherwise produce weak phase contrast in traditional imaging, by computationally extracting phase information from intensity variations.
Solution Approach 2:
The system performs preliminary measurements of intensity distributions at multiple axial positions before phase reconstruction. These preliminary intensity measurements, taken with high numerical aperture annular illumination, contain encoded phase information that is later decoded through the transport of intensity equation, allowing high resolution imaging without sacrificing phase contrast in the final reconstructed image.
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 method improves the efficiency and quality of quantitative phase imaging by achieving higher resolution and robust phase contrast, with flexible compatibility for various microscope objectives and improved light energy utilization.
Implementation Method 1
The LED array is placed at the front focal plane of the condenser... the light emitted by each of the illuminated LED units is converged by the condenser
Implementation Method 2
A programmable annular LED illumination-based high efficiency quantitative phase microscopy imaging method
Implementation Method 3
the light passes through the sample to be tested, is concentrated by the imaging tube lens and then reaches the imaging plane of the camera
Data Source
AI summary
The invention discloses a programmable annular LED illumination-based high efficiency quantitative phase microscopy imaging method, the proposed method comprising the following steps: the derivation of system optical transfer function in a partially coherent illumination imaging system; the derivation of phase transfer function with the weak object approximation under the illumination of tilted axially symmetric coherent point illumination source; the extension of illumination from an axially symmetric coherence point source to a discrete annular point source, and the optical transfer function can be treated as an incoherent superposition of each pair of tilted axially symmetric coherent point sources. The acquisition of raw intensity dataset; the implementation of deconvolution for quantitative phase reconstruction. The invention derives the system phase transfer function under the tilted axially symmetric point light source in the case of partially coherent illumination, and promotes the optical phase transfer function of the discrete annular point light source. The programmability characteristic of LED array enables the annular illumination aperture to be flexibly adjustable, being applicable to different microscopic objects with different numerical apertures, and improving the compatibility and flexibility of the system.