Spectral Wavefront Analysis for Ocular Metrology
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Solution Overview
Problem
Current metrology techniques for the human eye, such as hyperspectral imaging and wavefront analysis, face challenges in maintaining accurate relative phase information between sampling points and wavelengths, especially due to motion artefacts and the difficulty in achieving high accuracy in three-dimensional scans.
Innovation Solution
A spectral wavefront analyser system that uses a two-dimensional sampling array with micro lens arrays to extract optical phase and spectral information from multiple sampling points in a single acquisition, employing dispersive elements like gratings and polarisation optics to reduce motion artefacts and provide balanced detection, enabling accurate tomographic profiling of the eye's anterior segment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional scanning-based wavefront analysis is used, then detailed optical phase information can be obtained, but motion artefacts increase and measurement time increases
Solution Approach 1:
The wavefront is segmented into multiple discrete sampling points arranged in a two-dimensional array, allowing simultaneous measurement of optical phase at each point through the interferometric system, thereby eliminating the need for sequential scanning and reducing motion artefacts
Solution Approach 2:
The measurement approach transitions from one-dimensional sequential scanning to two-dimensional parallel sampling, where multiple beamlets illuminate different spatial points simultaneously and the interferometric detector captures phase information across the entire wavefront in a single acquisition
2Loss of information
If hyperspectral imaging is used to gather intensity information, then spectral features can be analysed, but phase information is lost
Solution Approach 1:
The system merges interferometric wavefront sensing with spectral imaging by combining a beam splitter, dispersive element, and two-dimensional detector array, enabling simultaneous capture of both intensity and phase information across multiple wavelengths in a single measurement
Solution Approach 2:
The interferometric spectral imaging system serves multiple functions: it performs wavefront analysis, spectral analysis, and tomographic profiling simultaneously, eliminating the need for separate measurement systems and reducing overall device complexity
3Measurement precision
If multi-wavelength wavefront analysis is performed, then dispersive properties can be measured, but relative phase information between wavelengths is not obtained
Solution Approach 1:
A dispersive element acts as an intermediary that spatially separates different wavelengths in the spectral direction while the interferometric setup maintains phase coherence across wavelengths, allowing the detector to capture relative phase information between different spectral components
Solution Approach 2:
The system replaces complex mechanical phase-shifting equipment with a stationary interferometric arrangement combined with spectral dispersion, using optical field interference patterns to encode phase information that can be decoded through computational algorithms
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 precise measurement of optical phase and spectral information across a multi-wavelength wavefront, reducing motion artefacts and enabling high-resolution, single-shot acquisitions of ocular data, including corneal topography and wavefront analysis, with improved accuracy and reduced clinical complexity.
Implementation Method 1
an interferometric arrangement in which an incoming known multi-wavelength wavefront is divided by a beam splitter into reference and probe beams
Implementation Method 2
A dispersive element such as a grating 225 which angularly disperses the wavelength components of the light
Implementation Method 3
A spectral wavefront analyser system that uses a two-dimensional sampling array with micro lens arrays
Implementation Method 4
extract optical phase and spectral information from multiple sampling points in a single acquisition, employing dispersive elements like gratings and polarisation optics
Data Source
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Figure 3~3a
AI summary
Method and systems are presented for analysing a wavefront using a spectral wavefront analyser to extract optical phase and spectral information at a two dimensional array of sampling points across the wavefront, wherein the relative phase information between the sampling points is maintained. Methods and systems are also presented for measuring an eye by reflecting a wavefront of an eye and measuring the wavefront at a plurality of angles to provide a map of the off-axis relative wavefront curvature and aberration of the eye. The phase accuracy between wavelengths and sample points over a beam aperture offered by these methods and systems have a number of ocular applications including corneal and anterior eye tomography, high resolution retinal imaging, and wavefront analysis as a function of probe beam incident angle for determining myopia progression and for designing and testing lenses for correcting myopia.