Structured Illumination Microscopy 3D Height Mapping
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Solution Overview
Problem
Existing microscope systems fail to create a 3D height map of specimens with good Z resolution and independence from surface structure, particularly when neighboring points have different heights and reflectivity, and are sensitive to local slopes and aberrations.
Innovation Solution
A method using sinusoidal spatial patterns with rounded and digitized light intensity in at least two levels, involving two or three orthogonal sinusoidal patterns, and a scanning process that alternates phase changes in both spatial directions, combined with a weighing factor for enhanced sensitivity and reduced acquisition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional structured illumination microscopy methods are used, then 3D height map can be obtained, but the Z resolution is poor and the measurement is highly sensitive to surface structure variations, local slopes, and aberrations
Solution Approach 1:
The illumination pattern is segmented into multiple sinusoidal components with different orientations (at least two orthogonal directions). This segmentation allows the system to capture height information from multiple independent measurements, improving both Z resolution and reliability by averaging out surface structure variations and local slope effects across different pattern orientations
Solution Approach 2:
The patent employs periodic sinusoidal illumination patterns that are systematically varied in phase and orientation. By using periodic patterns with known wavelengths and systematically changing their parameters, the system achieves high Z resolution through precise phase detection while the periodic nature helps average out sensitivity to local surface variations
2Measurement precision
If multiple sinusoidal patterns with different phases are used to improve Z resolution, then the measurement becomes more sensitive to surface structure variations and local slopes
Solution Approach 1:
The system changes parameters of the illumination pattern systematically - specifically the phase and orientation angles of sinusoidal patterns. By controlling these parameter changes in a structured manner (at least two orthogonal directions with specific phase relationships), the system achieves high Z resolution while managing complexity through mathematical relationships between the patterns
Solution Approach 2:
The multi-directional sinusoidal patterns serve multiple functions simultaneously: they provide phase information for Z resolution, orientation diversity for reducing surface structure sensitivity, and redundant measurement paths for improving reliability. This multi-functionality allows the system to achieve multiple goals without proportionally increasing complexity
3Reliability
If conventional single-direction sinusoidal patterns are used, then the system is sensitive to local slopes and surface structure, but using multi-directional patterns increases acquisition time
Solution Approach 1:
The patent merges multiple sinusoidal patterns from different orientations into a unified measurement system. By combining at least two orthogonal sinusoidal patterns and processing them together through envelope detection, the system achieves surface structure independence while reducing total acquisition time compared to sequential single-direction measurements
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
The method provides a 3D height map with improved Z resolution and reduced sensitivity to surface structure variations and aberrations, allowing for accurate height determination across diverse specimen surfaces.
Implementation Method 1
The light reflected by the surface in scanning positions with the spatial pattern having corresponding spatial pattern positions is detected
Data Source
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AI summary
In a method and apparatus for determining the height of a plurality of spatial positions on a surface of a specimen, a light beam is projected on the surface. The light beam has a sinusoidal spatial pattern in at least two directions perpendicular to an optical axis of the light beam, and which is moved to different spatial pattern positions. The surface is scanned along said optical axis in different scanning positions. A fixed relationship between a moving distance between subsequent spatial pattern positions, and a scanning distance between subsequent scanning positions exists. The light reflected by the surface is detected in scanning positions with the spatial pattern having corresponding spatial pattern positions. From the detected light for each spatial position of the surface, an envelope curve of intensity values corresponding to scanning positions is determined. A maximum of the envelope curve and its corresponding scanning position being representative of the height of the spatial position of the surface is selected. The spatial pattern is moved in a sequence of 2n steps (n > 2) in a first and a second spatial direction over a distance of 1/4 and 1/n pattern wavelength, respectively.