Smartphone Refractive Error Measurement Using Inverse Shack-Hartmann Technique
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Solution Overview
Problem
Existing handheld consumer devices for self-refraction are not as accurate or economical as needed for measuring refractive properties of optical systems, particularly the human eye, due to limitations in optical design and usability.
Innovation Solution
The use of the inverse Shack-Hartmann technique in conjunction with a smartphone as a light source, simulating the cross-cylinder procedure by adjusting the distance between parallel lines to assess refractive errors, with improvements such as high-resolution measurements and intentional coma to aid alignment, utilizing a micro-lens array or pinhole array for accurate refractive error detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing handheld consumer devices are used for self-refraction, then the device complexity is reduced and ease of operation is improved, but the measurement precision and reliability are insufficient
Solution Approach 1:
The patent introduces a micro-lens array as an intermediary component between the smartphone camera and the test subject's eye. This micro-lens array acts as a mediating optical element that enables precise refractive error measurement while keeping the overall device simple and based on a consumer smartphone platform.
Solution Approach 2:
The patent makes the smartphone camera serve multiple functions: it acts as both the light source controller and the imaging device for refractive measurement. The single device performs what would traditionally require separate specialized instruments, thereby reducing device complexity while maintaining measurement precision.
2Measurement precision
If a micro-lens array or pinhole array is used for accurate refractive error detection, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent employs inexpensive micro-lens arrays or pinhole arrays that can be mass-produced and integrated into the smartphone device. These components are simple, low-cost optical elements that provide high measurement precision without requiring complex or expensive optical systems.
3Ease of operation
If the cross-cylinder procedure is simulated by adjusting line distance, then the ease of operation is improved and usability is enhanced, but the measurement precision may be compromised
Solution Approach 1:
The patent implements a feedback mechanism where the smartphone camera captures the user's visual response to the simulated cross-cylinder procedure. The system processes this visual feedback to automatically calculate and determine the refractive error, thereby maintaining measurement precision while simplifying the user's operational tasks.
Solution Approach 2:
The patent replaces the traditional mechanical cross-cylinder lens flipping mechanism with a digital simulation using parallel lines displayed on the smartphone screen. This substitution eliminates complex mechanical components while preserving the diagnostic functionality and improving ease of operation.
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 method provides a more accurate and user-friendly way to measure refractive errors by leveraging high-resolution smartphone screens and optical systems, allowing for precise detection of refractive errors and correction, improving visual acuity and reducing noise in astigmatism measurements.
Implementation Method 1
The optical input of a disclosed device can originate from a smart phone, personal electronic device or other optical system... After the light passes through the optical system, at the imaging plane two lines are formed
Implementation Method 2
The coma, or comatic aberration, in an optical system referring to an aberration inherent to certain optical designs or due to imperfection in the lens or other components that results in off-axis point sources such as pixels forming a line are appearing distorted, appearing to have a tail (coma) like a comet
Implementation Method 3
Disclosed systems and methods include methods that simulate or replicate an optometrist's cross-cylinder examination that utilizes the inverse Shack-Hartmann technique
Data Source
AI summary
Disclosed embodiments may include a device, system and method for providing a low cost device that can measure refractive errors very accurately via attachment to a smart phone. A disclosed device may use ambient light or a light source in simulating the cross cylinder procedure that optometrists use by utilizing the inverse Shack-Hartman technique. The optical device may include an array of lenslets and pinholes that will force the user to effectively focus at different depths. Using an optical device, in conjunction with a smart phone, the user first changes the angle of the axis until he/she sees a cross pattern (the vertical and horizontal lines are equally spaced). The user adjusts the display, typically using the controls on the smartphone, to make the lines come together and overlap, which corresponds to bringing the view into sharp focus, thus determining the appropriate optical prescription for the user.