Variable Shape Mirror Actuator for Ophthalmologic Aberration Correction
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Solution Overview
Problem
Current ophthalmologic imaging apparatuses face challenges in achieving high-resolution images of the ocular fundus due to aberrations caused by optical tissues within the eye, leading to difficulties in early detection of ocular fundus diseases, particularly at the visual cell level, and existing reflective optical modulation devices are bulky and inefficient in correcting wavefront aberrations.
Innovation Solution
An ophthalmologic apparatus with a reflective optical modulation device featuring a variable shape mirror with 61 or more actuators within a 7.5 mm effective diameter, capable of achieving a Strehl ratio of 0.8 or more, allowing for high-resolution imaging by correcting wavefront aberrations with a large stroke length and high-density actuator arrangement, enabling detailed observation of visual cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflective liquid crystal device is used to correct wavefront aberrations, then the aberration correction function is achieved, but the optical system size increases due to requiring two optical elements
Solution Approach 1:
The patent extracts and eliminates one of the two optical elements required by reflective liquid crystal devices. By using a variable shape mirror instead, the system achieves aberration correction with a single optical element, thereby reducing the overall optical system size while maintaining the correction function.
Solution Approach 2:
The patent replaces the liquid crystal-based optical modulation system with a mechanically actuated variable shape mirror system. This substitution eliminates the need for polarization modulation and associated optical elements, achieving both size reduction and improved suitability for multi-wavelength observation.
2Reliability
If a reflective liquid crystal device is used for wavefront correction, then aberration correction is achieved, but the device becomes unsuitable for multi-wavelength observation due to high wavelength dependence
Solution Approach 1:
The patent replaces the wavelength-dependent liquid crystal modulation mechanism with a mechanically actuated variable shape mirror. The mirror's shape is controlled by actuators that physically deform the reflective surface, a mechanism that is inherently wavelength-independent and thus suitable for multi-wavelength observation while maintaining aberration correction functionality.
3Measurement precision
If the number of actuators within the effective diameter is increased to improve aberration correction precision, then the correction precision is improved, but the device complexity increases
Solution Approach 1:
The patent divides the variable shape mirror surface into multiple segments or zones, each controlled by independent actuators. This segmentation allows for precise local control of the mirror surface shape to correct different spatial frequency components of wavefront aberrations. The segmented approach achieves high correction precision while managing device complexity through modular actuator design.
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
The apparatus achieves high-resolution imaging of visual cells, enabling early detection of ocular fundus diseases and reducing the size of the optical system while maintaining effective aberration correction, facilitating detailed observation of ocular fundus structures.
Implementation Method 1
The variable shape mirror corrects the wavefront by deforming the mirror shape and thus by generating an optical path length difference within the effective diameter in the optical axis direction.
Implementation Method 2
A reflective optical modulation device includes a plurality of actuators and a reflection mirror
Data Source
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Figure 3A~3F
AI summary
An ophthalmologic apparatus includes an aberration measuring means configured to measure wavefront aberration of returning light, and a reflective optical modulation device configured to modulate the returning light. A control means controls the reflective optical modulation device to correct the wavefront aberration of the returning light based on a measurement result of the aberration measuring means. The reflective optical modulation device includes a reflection mirror of which the diameter of an effective region (effective diameter) that reflects the measurement light or the returning beam is 7.5 mm or less, and 61 or more actuators that act on the reflection mirror within the effective diameter. Each of the actuators includes an interdigital electrode having a maximum displacement of 7.5 µm or more.