Ophthalmic Eye Alignment Using Iris Projection Patterns
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Solution Overview
Problem
Existing ophthalmic instruments face challenges in achieving proper alignment with the eye, leading to undesirable results such as dim or vignette views and out-of-focus images due to improper positioning, which current alignment methods fail to satisfactorily address.
Innovation Solution
The ophthalmic apparatus employs an optical radiation source that directs rays of radiation in a converging manner toward a reference plane, forming predefined guidance and alignment patterns on the iris, which indicate the correct alignment by projecting specific sub-patterns based on the distance and position of the eye relative to the apparatus, utilizing infrared and visible light, and includes a pupil camera for image capture and data processing to guide the user to the optimal alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment methods are used, then the ophthalmic instrument can be positioned relative to the eye, but the alignment precision is insufficient leading to dim or vignetted views and out-of-focus images
Solution Approach 1:
The system performs preliminary alignment by projecting guidance patterns onto the iris before actual imaging begins. The alignment pattern is projected in advance to establish the correct optical axis and working distance, ensuring that subsequent images are properly focused and free from vignetting.
Solution Approach 2:
An alignment pattern consisting of multiple sub-patterns is introduced as an intermediary element between the ophthalmic instrument and the eye. This pattern serves as a mediator to indicate alignment status and guide the user to achieve proper positioning without directly affecting the eye or the imaging process.
2Illumination intensity
If the ophthalmic instrument is positioned closer to the eye to improve image brightness, then illumination intensity increases, but alignment precision deteriorates due to loss of working distance control
Solution Approach 1:
The system provides visual feedback through the alignment pattern projected onto the iris. The pattern's appearance and position give real-time information about alignment quality, allowing the user to adjust positioning while maintaining optimal working distance and image brightness simultaneously.
Solution Approach 2:
The correct working distance and optical axis are established in advance through the alignment pattern projection. This preliminary positioning ensures that subsequent imaging is performed at the optimal distance for both brightness and precision.
3Measurement precision
If multiple alignment parameters need to be adjusted simultaneously, then comprehensive alignment can be achieved, but the ease of operation decreases due to complex adjustment procedures
Solution Approach 1:
The alignment pattern is divided into multiple sub-patterns, each indicating different alignment parameters. This segmentation allows the user to understand and adjust various alignment aspects independently through a single visual reference, simplifying the operation while maintaining comprehensive alignment precision.
Solution Approach 2:
The alignment pattern serves as an intermediary that translates complex multi-parameter alignment requirements into simple visual information. Instead of requiring separate adjustments for each parameter, the pattern provides integrated feedback that guides comprehensive alignment through straightforward observation and adjustment.
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 ensures precise alignment of the ophthalmic instrument with the eye, enabling focused and reflection-free imaging by projecting alignment patterns on the iris, allowing for accurate observation and image capture, thereby improving the quality of ophthalmic examinations.
Implementation Method 1
rays of optical radiation are directed in a converging manner toward a reference plane
Implementation Method 2
an optical system forming an image of a predefined guidance pattern
Data Source
AI summary
An ophthalmic apparatus includes an optical radiation source, which direct rays of optical radiation in a converging manner toward a reference plane, and causes the projections of the rays of optical radiation on a plane parallel to the normal of the reference plane to cross at a plane parallel to the reference plane and located deterministically relative to the reference plane, the crossing forming an alignment pattern of optical radiation on the reference plane. The ophthalmic apparatus, when directed toward the eye, captures images in a direction toward the reference plane including an area, where rays of optical radiation cross, and presents information on a pattern formed by the rays on a surface of a person or mammal whose eye the ophthalmic apparatus is directed toward. The alignment pattern when projected on an iris of the eye indicates that the iris of the eye is at the reference plane.