Shack-Hartmann Wavefront Sensor for Ophthalmic Optical Zone Diameter Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current interferometry-based systems are inaccurate for measuring the optical zone diameter of soft contact lenses, particularly for low-power lenses due to less pronounced variations in thickness profiles, making it difficult to distinguish the optical zone boundary from the peripheral region.
Innovation Solution
A Shack-Hartmann wavefront sensor system that includes a light source, an array of lenslets, and a computing device to capture and analyze images of ophthalmic devices, detecting the optical zone boundary by selecting distorted spots and fitting a curve to measure the diameter, which is more robust and cost-effective than interferometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interferometry is used for OZ diameter measurement, then lens power characterization can be performed, but measurement accuracy deteriorates for low-power soft contact lenses
Solution Approach 1:
The patent changes the measurement parameter from interference pattern analysis to wavefront slope measurement. By using a Shack-Hartmann wavefront sensor to measure local wavefront slopes and integrate them to obtain wavefront height, the system can accurately detect OZ boundaries even for low-power lenses where interference patterns are not pronounced. This parameter change enables accurate measurement across the full range of lens powers.
2Reliability
If interferometry-based systems are used, then OZ boundary detection can be performed, but measurement reliability worsens due to difficulty distinguishing boundary from peripheral region
Solution Approach 1:
The patent segments the wavefront measurement into multiple local slope measurements taken at different pupil zones. By dividing the pupil into concentric rings and measuring wavefront slopes in each zone, then integrating these segmented measurements to reconstruct the complete wavefront, the system can clearly identify the OZ boundary where the wavefront height changes, making boundary detection reliable even when interference patterns are not visible.
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 system accurately measures the optical zone diameter of ophthalmic devices, including low-power contact lenses, providing precise characterization of the boundary and improving measurement accuracy compared to interferometry-based methods.
Implementation Method 1
interferometry uses waves (e.g., light) to create interference patterns
Implementation Method 2
The Shack-Hartmann wavefront sensor includes an array of lenslets and a photon sensor
Implementation Method 3
the light source is a collimated light source or a point source
Implementation Method 4
the computing device is configured to analyze the image to detect an optical zone (OZ) boundary of the ophthalmic device and measure a diameter of the OZ boundary
Data Source
AI summary
Systems and methods for characterizing optical zone diameter of ophthalmic devices are described herein. An example system includes a light source, a Shack-Hartmann wavefront sensor, and a computing device operably coupled to the wavefront sensor. The computing device includes a processor and a memory operably coupled to the processor. The computing device is configured to receive an image of an ophthalmic device, where the image is captured by the wavefront sensor. The computing device is also configured to analyze the image to detect an optical zone (OZ) boundary of the ophthalmic device and measure a diameter of the OZ boundary of the ophthalmic device.