Eye Biometric Interferometry Axis Alignment
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Solution Overview
Problem
Existing interferometric methods for determining biometric parameters of the eye require precise alignment of the optical axis of the measurement device with the eye, which is time-consuming and unreliable, especially due to deviations between the visual and optical axes caused by imaging errors and ametropia.
Innovation Solution
A method and device that automatically align the optical axis of the biometric measuring system with the eye using a fixation light source and image sensor to determine angular deviations, allowing for refixation and superimposing measuring light with external reference light for diffraction-limited detection, enabling precise and reliable biometric parameter determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precise manual alignment of the optical axis is performed, then measurement reliability is improved, but measurement time increases and the process becomes less reliable in clinical practice
Solution Approach 1:
The system performs self-alignment by automatically detecting the angular deviation between the visual and optical axes using the fixation light and image sensor, then adjusting the optical axis alignment without requiring manual operator intervention. This self-service mechanism eliminates time-consuming manual alignment while maintaining measurement reliability.
Solution Approach 2:
The system uses feedback from the image sensor to detect the position of reflections from the fixation light, calculates the angular deviation, and automatically adjusts the alignment based on this feedback. This closed-loop feedback mechanism enables automatic alignment that is both fast and reliable.
2Measurement precision
If the visual axis and optical axis are aligned with high precision, then interference signal quality is improved, but the complexity of the alignment procedure increases
Solution Approach 1:
The fixation light serves as an intermediary element that facilitates automatic alignment. By projecting a known light pattern and detecting its reflections, the system can calculate angular deviation and achieve precise optical axis alignment without complex manual procedures. The intermediary fixation light simplifies the alignment process while maintaining high measurement precision.
3Measurement precision
If diffraction-limited detection is used, then measurement accuracy is improved, but sensitivity to eye tilting increases
Solution Approach 1:
The system performs preliminary alignment of the optical axis with the visual axis using the fixation light and image sensor before conducting the interferometric measurement. This preliminary action ensures that the eye is properly positioned and tilted, allowing diffraction-limited detection to be performed without sensitivity to eye tilting during the actual measurement.
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 approach ensures accurate and robust biometric measurements by automatically aligning the optical axes, increasing sensitivity and reliability, and reducing dependence on precise initial alignment, thereby delivering precise and reliable measured values.
Implementation Method 1
the eye is illuminated by a measuring light source with a measuring beam and by a fixation light source with a fixation mark, recorded by an image sensor with the reflections that have arisen
Implementation Method 2
superimposed as a measuring beam with an external reference beam, directed to the measuring sensor and H) the interferometric measuring signals are evaluated
Implementation Method 3
an existing optic is designed in such a way that, first Line quasi diffraction-limited volume scattered light is detected
Data Source
AI summary
The invention relates to the determination of biometric parameters of an eye, wherein the optical axis of the biometric measurement system is aligned to the optical axis of an eye and ideally coincides with said axis. The device consists of an interferometry measuring arrangement having a measurement light source and a measurement sensor (2), a fixing light source (3) for capturing the eye (1) with the reflexes that arise, an image sensor (4), and lens (5) for detecting volume scattered light and an analysis unit for determining the angular deviation of the optical axis (6) of the eye (1) from the optical axis of the biometric measurement system. The analysis unit is capable of comparing the determined angular deviation to a predefined tolerance and, in order to refix the fixing light source as a result of said comparison, of having laterally displaced fixing marks generated on the basis of the calculated angular deviation, or of initiating the biometric measurement. The proposed solution is primarily intended for ophthalmological devices for biometrically measuring the distances and radii in the eye.