Smartphone Refraction Measurement Self-Calibration
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Solution Overview
Problem
Current vision testing and refraction measurement systems face challenges in accurately determining display resolution and correcting for optical aberrations, particularly in smartphone-based systems where phone resolution is not reliably reported, leading to distorted images and complex, expensive hardware solutions.
Innovation Solution
A method and apparatus for self-calibration to measure display resolution by aligning a rectangle on the screen with known device dimensions, using external sensors with touch points, and pre-distorting images to correct for distortion aberrations, ensuring accurate alignment and scaling for vision and refraction measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If smartphone display resolution is used for vision testing, then portability and ease of use are improved, but measurement precision deteriorates due to unreliable resolution reporting
Solution Approach 1:
The system performs self-calibration by using the known dimensions of the attached device (e.g., smartphone) to automatically determine the display resolution. The user aligns the device with visual targets on the screen, and the system calculates PPI based on the alignment data, eliminating the need for manual resolution input or external calibration equipment.
Solution Approach 2:
The system uses feedback from the user's alignment actions (matching the device outline with visual targets) to iteratively refine the display resolution measurement. The alignment data is processed to calculate the actual PPI, which then feeds back into the correction algorithms for subsequent vision measurements.
2Measurement precision
If hardware solutions are used to correct optical aberrations, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system replaces complex optical hardware correction mechanisms with software-based pre-distortion algorithms. Instead of using additional lenses or optical elements to correct aberrations, the system digitally pre-distorts the visual targets to compensate for known optical distortions, achieving correction through computational methods rather than mechanical/optical additions.
Solution Approach 2:
The system performs preliminary correction by pre-distorting the visual targets before they are displayed to the user. The distortion characteristics are calculated in advance based on the optical system's properties, and the correction is embedded in the displayed images themselves, eliminating the need for real-time hardware adjustment during measurement.
3Measurement precision
If professional eye exam processes are followed, then measurement precision is improved, but loss of time and convenience deteriorate due to appointments and travel
Solution Approach 1:
The system enables users to perform comprehensive vision and refraction measurements themselves at home, eliminating the need for scheduled appointments, travel to clinics, and waiting in lines. The automated calibration and measurement process guides users through the procedure independently, maintaining professional-grade accuracy while providing the convenience of self-administration.
Solution Approach 2:
The system combines multiple professional eye exam functions (display resolution calibration, optical aberration correction, refraction measurement, vision acuity testing) into a single integrated platform that can be used at home. This multi-functional approach replaces the need for multiple separate professional equipment and appointments with one comprehensive device.
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 and cost-effective self-administered vision testing at home, meeting professional standards, with improved user experience and reduced complexity, by correcting for optical aberrations and determining display resolution through user input and sensor-based calibration.
Implementation Method 1
using a first lens for demagnification; using a second and third lens, with the second and third lens each defining one slit
Data Source
AI summary
Consumer products such as refraction measurement devices may be used for obtaining refraction measurements allow consumers to track their vision without visiting an optometrist or ophthalmologist. Such consumer products may work in concert with smart phones or other products having a touch screen that present images to refraction measurement devices. Smart phones may have resolution rates, sometimes measured as PPI or pixels per inch that are unknown to the user and/or refraction measurement device. One aspect of the invention is to provide an optical interface for the user to manually match the view port boundary of the smartphone to comport with the view port boundary of the refraction measurement device. Another aspect of the invention is the use of pre-distortion in images presented to the user. By noting the corrective movements exerted by the user upon the refractive measurement device, the user's own refractive error can be derived.