Ophthalmic Apparatus Abnormality Detection Optical Path
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Solution Overview
Problem
Ophthalmic apparatuses face difficulties in accurately determining whether abnormalities in interference signals from measured subject eyes are due to capturing state issues or actual lesions, especially when vibrations, shocks, or changes in light source conditions occur, making it challenging to distinguish between measurement errors and anatomical abnormalities.
Innovation Solution
Incorporating an abnormality detection optical system with a predetermined optical path length to generate and detect abnormality detection interference light simultaneously with measurement interference light, allowing the processor to analyze waveforms and determine if abnormalities are present in the capturing state or the subject eye itself by comparing signal characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an ophthalmic apparatus measures a subject eye using interference light, then tomographic images of the subject eye can be obtained, but abnormalities in the interference signal may occur due to vibration, shock, or light source changes, making it impossible to measure accurately
Solution Approach 1:
The patent introduces a reference optical path with a reference mirror as an intermediary system. This reference path generates reference interference signals that serve as a baseline for comparison. By comparing the measurement interference signals against these reference signals, the system can identify and exclude measurements affected by vibration, shock, or light source instability, thereby maintaining both measurement accuracy and signal reliability.
Solution Approach 2:
The system implements feedback by continuously monitoring the interference signals and comparing them against reference signals. When abnormalities are detected in the measurement signals, the system uses the reference signal comparison results to determine whether to accept or reject the measurement data, creating a closed-loop quality control mechanism that ensures reliable measurements.
2Difficulty of detecting and measuring
If the interference signal wobbles compared to normal state, then it becomes difficult to determine whether the abnormality is caused by capturing state or presence of lesion, but the patent enables differentiation between measurement state abnormalities and anatomical issues
Solution Approach 1:
The patent segments the interference signal analysis into two distinct components: reference signal characteristics (reflecting measurement conditions) and measurement signal characteristics (reflecting both measurement conditions and eye structure). By separately analyzing these segments and comparing them, the system can identify whether abnormalities originate from the measurement process or from actual eye lesions, preventing loss of diagnostic information.
Solution Approach 2:
The reference interference signal acts as an intermediary that carries information about measurement conditions without containing information about eye lesions. By using this intermediary for comparison, the system can isolate and identify the source of abnormalities, making it easier to detect and classify the nature of signal deviations.
3Object-affected harmful factors
If vibration or shock causes abnormality in interference signal, then accurate measurement becomes impossible, but the patent enables detection of such measurement state abnormalities
Solution Approach 1:
The reference optical path serves as an intermediary that is equally affected by vibration and shock but does not contain diagnostic information about the eye. By comparing measurement signals against reference signals, the system can identify and compensate for the effects of vibration and shock, maintaining measurement accuracy even in the presence of these harmful factors.
Solution Approach 2:
The patent converts the harmful effect of vibration and shock into a useful diagnostic tool. By using the reference signal to detect these disturbances, the system can identify which measurements were affected and exclude them from final results, thereby converting the potential harm of environmental disturbances into a quality control mechanism that improves overall measurement reliability.
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 differentiation between measurement state abnormalities and anatomical issues, ensuring reliable tomographic imaging by discarding data from abnormal measurement states and generating images only from normal data, thus improving the accuracy of subject eye evaluations.
Implementation Method 1
an interference signal being a combination of the reflected light guided by the measurement optical system and the reflected light guided by the reference optical system
Data Source
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AI summary
An ophthalmic apparatus includes: a light source; a measurement optical system that irradiates an eye with light from the source and guides reflected light from the eye; a reference optical system that guides the light from the source to use the light from the source as reference light; an abnormality detection optical system that has an optical path length of a predetermined length and to guide the light from the source to use the light from the source as abnormality detection light; a light receiving element that receives measurement interference light being combination of the reflected light from the eye and the reference light and abnormality detection interference light being combination of the abnormality detection light and the reference light, and the ophthalmic apparatus determines whether the measurement interference light is abnormal based on waveform of an abnormality detection interference signal outputted from the light receiving element.