Digital Holographic Microscope Non-Linear Beam Scanning
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Solution Overview
Problem
Current digital holographic microscopy methods, particularly the on-axis method, require multiple holograms for three-dimensional tomographic measurements, making them time-consuming, whereas the off-axis method is still a developing technique in need of an efficient optical measurement system for such applications.
Innovation Solution
An interferometric method using a laser beam split into a reference and object beam, forming an interference pattern, with non-linear scanning to detect multiple interference patterns and reconstruct a three-dimensional image, maintaining constant fringe pitch to enhance resolution and field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the on-axis method is used to reconstruct the object image, then the measurement precision can be achieved, but the measurement time increases significantly due to requiring multiple holograms
Solution Approach 1:
The patent applies dynamics by rotating the object beam at a constant angular velocity to continuously change the incident angle dynamically. This allows the system to capture multiple interference patterns over time without requiring multiple static hologram acquisitions, thereby reducing total measurement time while maintaining reconstruction precision through temporal sampling of angular variations.
Solution Approach 2:
The patent implements periodic action by rotating the object beam in a continuous cyclic manner to sweep through different incident angles. This periodic angular scanning enables the acquisition of multiple interference patterns in a single continuous operation rather than requiring separate measurements for each angle, thus reducing measurement time while preserving the precision needed for accurate image reconstruction.
2Loss of time
If the off-axis method is used for three-dimensional measurements, then the measurement time is reduced, but the technique is not mature and lacks an efficient optical measurement system
Solution Approach 1:
The patent resolves the immaturity of the off-axis method by introducing dynamic angular scanning with constant angular velocity. This controlled dynamic approach systematically varies the incident angle to optimize the interference pattern quality, enabling the off-axis method to achieve reliable three-dimensional measurements with improved axial resolution and symmetric reconstruction, thereby maturing the technique.
Solution Approach 2:
The patent changes the parameter of incident angle dynamically during measurement by rotating the object beam. This parameter change allows the system to sweep through optimal angles for interference pattern formation, enhancing the performance of the off-axis method and creating an efficient optical measurement system that achieves both speed and accuracy for three-dimensional measurements.
3Measurement precision
If linear scanning is used to detect multiple interference patterns, then the three-dimensional reconstruction can be achieved, but the axial resolution and symmetric reconstruction are not optimized
Solution Approach 1:
The patent applies spheroidality by rotating the object beam in a circular arc rather than using linear scanning. This curved scanning path maintains a constant angular velocity and ensures symmetric angular coverage around the optical axis, which optimizes axial resolution and produces symmetric reconstruction in both x and y directions, overcoming the limitations of linear scanning approaches.
Solution Approach 2:
The patent addresses reconstruction symmetry by using asymmetric scanning geometry - rotating the object beam in an arc that maintains constant angular velocity while varying the incident angle non-uniformly. This asymmetric angular progression compensates for optical path differences and achieves symmetric image reconstruction, whereas simple linear scanning produces asymmetric results due to uniform spatial rather than angular sampling.
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 approach allows for efficient three-dimensional imaging with improved axial resolution and symmetric reconstruction along both axes, reducing measurement time and optimizing fringe pitch for high-resolution imaging.
Implementation Method 1
combining the reference beam with the object beam passed through the sample to form an interference pattern
Data Source
AI summary
An interferometric method for detecting information about a sample includes emitting a laser beam; splitting the laser beam into a reference beam and an object beam; transmitting the object beam through the sample in an incident angle; combining the reference beam with the object beam passed through the sample to form an interference pattern; detecting the interference pattern, and non-linearly scanning the object beam in order to detect a plurality of interference patterns.