Diffractive Lens Wavefront Measurement Using Computational Intermediary
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Solution Overview
Problem
Conventional methods for measuring optical properties of diffractive lenses, such as those used in intraocular lenses, are limited by their inability to account for the discontinuities in the wavefront caused by diffractive zones, leading to inaccurate measurements when using lenslet arrays.
Innovation Solution
A method that involves sampling the wavefront of a diffractive lens, adjusting for the effects of diffractive components, and comparing the measured properties against those of a monofocal-equivalent lens to compensate for the discontinuities, using techniques like Fourier transforms and cross-checking with theoretical and clinical measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a lenslet array is used to measure a diffractive lens, then the measurement system can be simplified, but the measurement precision deteriorates because the method can only measure local wavefront slopes and does not measure the zonal optical discontinuities
Solution Approach 1:
The patent introduces a computational intermediary that processes the lenslet array measurements by comparing them against theoretical wavefront predictions. This intermediary component reconciles the simplified measurement approach with the complex diffractive lens properties, enabling accurate measurement without requiring complex hardware modifications.
Solution Approach 2:
The patent replaces mechanical complexity with computational methods. Instead of using a mechanically complex wavefront sensor capable of detecting discontinuities directly, the system uses a simple lenslet array combined with computational algorithms that process the simplified measurements to achieve accurate wavefront characterization.
2Productivity
If coarse sampling is used to measure the wavefront, then the measurement process is simplified, but the measurement precision deteriorates because the sampling may cross zone boundaries and fail to capture true wavefront features
Solution Approach 1:
The patent implements feedback through iterative comparison of measured wavefront data against theoretical predictions. The system continuously refines the sampling and measurement process by using theoretical models to guide and correct the sampling, ensuring accuracy even with simplified measurement approaches.
Solution Approach 2:
The patent changes the parameter of wavefront representation by transforming the physical wavefront measurements into a computational model space. This allows the system to work with simplified sampled data while maintaining precision through mathematical transformation and comparison with theoretical wavefront characteristics.
3Ease of operation
If the local slopes of individual zones are measured, then the measurement method remains simple, but the measurement precision deteriorates because the zonal optical discontinuities and phase delays are not captured
Solution Approach 1:
The patent introduces a computational intermediary that processes the simple local slope measurements and transforms them into accurate optical property characterizations. This intermediary layer reconciles the simplicity of slope measurement with the complexity of diffractive optical properties through mathematical processing.
Solution Approach 2:
The patent adds a computational dimension to the measurements. By transforming physical measurements into a mathematical model space and comparing against theoretical predictions, the system gains the ability to capture zonal discontinuities and phase delays without adding physical measurement complexity.
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
Enables accurate measurement of optical properties of diffractive lenses by accounting for the diffractive structure's effects, improving the precision of wavefront analysis and correcting for distortions, thereby enhancing the assessment of image quality and optical performance.
Implementation Method 1
Diffractive lenses typically utilize diffractive 'zones' that break up an optical wavefront with discontinuities. The lateral separations between the zone boundaries, and the optical phase delays at the zone boundaries, combine together to redirect the light in a controlled manner.
Implementation Method 2
The light that passes through each lenslet comes to a focus, and if the local wavefront is tilted, the focused spot is displaced laterally by a distance that represents the local slope of the lens over the region of the lenslet.
Implementation Method 3
The optical wavefront of a conventional monofocal imaging system can be used to determine the optical properties of an image created by the system.
Data Source
AI summary
A method for measuring the optical properties of multifocal ophthalmic lenses. Collimated light is passed through an ophthalmic lens and onto an array of lenslets. Light exiting the array of lenslets is detected by a sensor. Blurred spots and/or double spots may represent diffractive zones of the wavefront. A centroid of the spot or a brighter of two spots may be used to determine the lateral position of the spot. Theoretical calculations, laboratory measurements, clinical measurements and experimental image spots may be generated, compared and cross-checked to determine a monofocal equivalent lens. A Modulation Transfer Function (MTF) may be used to evaluate and compare a diffractive lens and a monofocal equivalent lens.