Dual-Beam Interferometry for Ophthalmic Length Measurement
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Solution Overview
Problem
Current ophthalmological length measurement techniques, particularly low-coherence interferometry, face challenges in sensitivity for denser cataracts and require complex image processing, with limited flexibility in measuring beam arrangement due to variable eye anatomy and inhomogeneous cataracts.
Innovation Solution
Dual-beam space-time domain wavelength interferometry allows for flexible positioning and sizing of the measuring beam within the pupil, using monochromatic dual-beams and a tunable laser, with imaging onto a photodetector array and image intensifier to enhance sensitivity and measurement accuracy, particularly for denser cataracts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low-coherence interferometry is used for ophthalmological length measurement, then measurement precision is improved, but sensitivity for denser cataracts deteriorates
Solution Approach 1:
The invention segments the measurement process by using multiple discrete beam positions within the pupil rather than a single beam. This allows the system to采集 interferometric data from multiple locations, improving both sensitivity for dense cataracts and measurement precision through spatial sampling of the eye's optical properties
Solution Approach 2:
The invention transitions from one-dimensional single-beam measurement to two-dimensional multi-beam spatial sampling across the pupil. By adding the spatial dimension of beam positioning, the system enhances sensitivity to cataract density variations while maintaining length measurement precision through comprehensive optical path sampling
2Adaptability or versatility
If flexible beam positioning is implemented to adapt to variable eye anatomy, then adaptability is improved, but device complexity increases
Solution Approach 1:
The invention implements dynamic beam positioning where the measuring beam can be flexibly directed to different pupil locations based on the specific eye anatomy and cataract distribution. This dynamic adaptability allows optimization of measurement paths without requiring complex mechanical reconfiguration, as the system can electronically steer beams to appropriate positions
Solution Approach 2:
The interferometric measurement system is designed with universal applicability to handle various eye anatomies and cataract conditions through a unified multi-beam approach. The same optical platform performs both adaptive beam positioning and interferometric measurement, eliminating the need for separate specialized subsystems and reducing overall device complexity
3Measurement precision
If image processing complexity is increased to handle variable anatomy, then measurement accuracy is improved, but processing time increases
Solution Approach 1:
The invention performs preliminary organization of interferometric data from multiple beam positions before final processing. By pre-processing and structuring the spatially-resolved interferometric signals, the system reduces the computational burden of subsequent analysis, enabling accurate adaptation to variable anatomy without excessive processing time
Solution Approach 2:
The invention replaces complex mechanical image processing with optical-domain signal separation techniques. By using optical methods to isolate and process interferometric signals from different beam positions, the system achieves accurate anatomical adaptation while minimizing computational processing time compared to purely digital image processing approaches
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 provides high sensitivity and flexibility in ophthalmological length measurement, enabling accurate assessments even for denser cataracts with shorter measurement times and improved usability by maximizing the energy flow and contrast of Fresnel zone-like interferograms.
Implementation Method 1
interference phenomena between the Purkinje-Sanson reflexes and the reflex of the fundus
Implementation Method 2
a tunable laser and by a beam splitter in a Michelson interferometer
Implementation Method 3
imaging onto a photodetector array and image intensifier to enhance sensitivity
Data Source
AI summary
Measurement of intraocular lengths by dual-beam Fourier low-coherence interferometry on the basis of Fresnel-zone-type space-time domain interferograms of the Purkinje-Sanson reflexes. The eye is illuminated by parallel, monochromatic dual beams having wavelengths which differ in temporal sequence. Wavelength spectra of space-time domain interferograms are imaged onto a photodetector array and registered. Viewing direction and position of the eye are fixed by optical aids and are monitored by acoustic and optical aids. A zoom optical unit in the output beam of the ophthalmological interferometer makes it possible, by simple focusing, to image virtual Fresnel-zone-type space-time domain interferograms from contrast-optimized positions onto the photodetector array or onto an image intensifier that is arranged in front of the photodetector array such that the position-dependent size change of the space-time domain interferograms is compensated by the scale change of this imaging.