Ophthalmic Interference Optics for Optical Path Drift Correction
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Solution Overview
Problem
Existing ophthalmic devices face challenges in accurately calculating depthwise position information due to changes in optical path length caused by post-shipment chronological changes and environmental factors, making it difficult to maintain consistent measurement conditions.
Innovation Solution
The device employs a switching mechanism to alternately detect measurement and reference interference light using separate optical paths, allowing for the setting of a reference position independent of the depthwise position information, and incorporates a storage unit to correct depthwise position information using pre-calibrated reference positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction reference light is generated by splitting light from the measurement optical system, then depthwise position information can be corrected for optical path length changes, but the reference position must be set at a position different from the depthwise position information, limiting measurement flexibility
Solution Approach 1:
The patent divides the reference light generation into two separate optical systems: a first reference optical system that generates first reference light for measurement interference, and a second reference optical system that generates second reference light for reference position calculation. This segmentation allows independent optimization of each system's function, enabling the reference position to be set at any desired location without being constrained by measurement light requirements.
Solution Approach 2:
The patent introduces a switching unit as an intermediary component that alternately switches between connecting the light source to the measurement optical system and to the second reference optical system. This intermediary enables temporal separation of measurement and reference position detection, allowing both functions to use the same light source while maintaining independent optical paths and flexible reference position setting.
2Ease of manufacture
If calibration is performed at the time of manufacture, then the optical system can be initially configured, but post-shipment chronological changes and environmental factors cause optical path length changes that degrade measurement accuracy over time
Solution Approach 1:
The patent performs preliminary calibration at the time of manufacture to establish initial reference positions, but also enables on-demand recalibration by detecting reference interference light at any measurement location. This preliminary action combined with flexible recalibration capability ensures initial setup simplicity while maintaining long-term measurement accuracy despite environmental changes.
Solution Approach 2:
The patent implements a feedback mechanism where the detected reference interference light is used to continuously monitor and correct optical path length changes. By comparing the detected reference position with previously stored reference positions, the system can identify drift caused by environmental factors and apply corrections to maintain measurement accuracy over time.
3Device complexity
If the same optical system is used for both measurement and reference light generation, then device complexity is reduced, but it becomes difficult to achieve consistent measurement conditions when optical path length changes occur
Solution Approach 1:
The patent introduces dynamic switching between different optical configurations using a switching unit. The system can dynamically reconfigure the optical path to connect the light source to either the measurement optical system or the second reference optical system as needed. This dynamic capability allows the system to maintain reliable measurement conditions by selectively activating the appropriate optical path while keeping the overall device structure relatively simple.
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 enables accurate and consistent measurement of depthwise position information by compensating for changes in optical path length, ensuring high precision in calculating depthwise lengths.
Implementation Method 1
reference light and measurement light are combined to generate measurement interference light, and depthwise position information of a subject eye is calculated from the generated measurement interference light
Implementation Method 2
a detector configured to detect the measurement interference light and output a measurement interference signal
Data Source
AI summary
An ophthalmic device that may include: a light source; a measurement optical system that generates measurement light; a first reference optical system that generates first reference light; a second reference optical system that generates second reference light; and an interference optical system that generates measurement interference light from the measurement light and the first reference light, and reference interference light from the first and second reference light. The measurement optical system may include a switching unit that switches between a first state in which the subject eye is irradiated with the light from the light source and a second state in which the light from the light source is guided to the second reference optical system branching from the measurement optical system. The controller may control the switching unit to detect the measurement interference light in the first state, and the reference interference light in the second state.