Objective Lens Diameter Optimization for Ophthalmologic Apparatus
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Solution Overview
Problem
Ophthalmologic apparatuses face challenges in optimizing the diameter of the objective lens to balance measurement range and accuracy across multiple optical systems, leading to compromised performance in refractive power measurement, keratometry, and OCT scans due to conflicting optimal working distances.
Innovation Solution
The ophthalmologic apparatus incorporates a configuration where the objective lens diameter is optimized to be greater than or equal to a lower limit value for secure OCT scan ranges and less than an upper limit value for effective keratometry, allowing shared use without deteriorating measurement accuracy or range, by projecting light patterns from the outer edge and using a keratometry plate for corneal shape measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the objective lens diameter is increased to secure OCT scan range, then the measurement range is improved, but the measurement precision for keratometry deteriorates
Solution Approach 1:
The patent applies parameter changes by establishing specific mathematical relationships for the objective lens diameter based on working distance, scan range, and corneal curvature radius. The diameter is calculated to fall within a specific range: greater than or equal to ((WD+d1)×SA/d2) and less than 2×((L+(R−√(R2−h2)))×tan(2×sin−1(h/R))+h−Δt/2), where WD is working distance, d1 is distance from corneal apex to pupil, d2 is distance from pupil to fundus, SA is scan range, L is distance from corneal apex to keratometry plate, h is image height, and R is corneal curvature radius. This parameter optimization allows the single lens to accommodate both OCT scanning and keratometry measurements without compromising either function.
2Measurement precision
If the objective lens diameter is decreased to improve keratometry measurement, then the measurement precision is improved, but the OCT scan range deteriorates
Solution Approach 1:
The patent resolves this contradiction by calculating the objective lens diameter within a specific mathematical range that simultaneously satisfies both keratometry precision requirements and OCT scan range requirements. The lower bound ensures sufficient OCT scan coverage while the upper bound maintains keratometry measurement precision. This parameter optimization allows the single lens to accommodate both functions without compromising either.
3Device complexity
If a single objective lens is shared by multiple optical systems, then the device complexity is reduced, but the measurement precision for each function deteriorates
Solution Approach 1:
The patent applies universality by designing a single objective lens that serves multiple functions: refractive power measurement, keratometry, and OCT scanning. The lens diameter is specifically optimized to accommodate all three functions simultaneously. The mathematical formulation ensures that the lens provides sufficient aperture for OCT scanning while maintaining the precision required for keratometry and refractive power measurement, thereby achieving multi-functionality without sacrificing measurement quality.
Solution Approach 2:
The patent uses parameter changes to optimize the objective lens diameter within a specific mathematical range that satisfies all three measurement functions. By carefully selecting the diameter within this calculated range, the system achieves both reduced complexity through lens sharing and maintained precision across all measurement types.
4Measurement precision
If the working distance is changed to optimize for one measurement type, then the measurement precision for that type is improved, but the scan range for OCT deteriorates
Solution Approach 1:
The patent applies parameter changes by establishing a mathematical relationship between working distance, lens diameter, scan range, and corneal geometry. The objective lens diameter is calculated as greater than or equal to ((WD+d1)×SA/d2), where WD is working distance, d1 is distance from corneal apex to pupil, d2 is distance from pupil to fundus, and SA is scan range. This parameter optimization allows the system to maintain both precise refractive power measurement and adequate OCT scan range at the same working distance without compromise.
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 configuration enables downsized apparatuses to perform accurate refractive power measurements, keratometry, and OCT scans within desired scan ranges without changing the working distance, reducing instrument myopia influence and ensuring high measurement precision.
Implementation Method 1
an objective lens; a refractive power measurement optical system configured to project light onto a subject's eye via the objective lens and to detect returning light from the subject's eye
Implementation Method 2
detect returning light from the subject's eye
Implementation Method 3
an inspection optical system that includes an optical scanner and is configured to deflect light from a light source, to project the light deflected by the optical scanner onto the subject's eye
Implementation Method 4
a keratometry plate that is disposed between the keratometry light source and the subject's eye and is formed a light transmitting part which penetrates light from the keratometry light source
Data Source
AI summary
An ophthalmologic apparatus includes an objective lens, a refractive power measurement optical system, an inspection optical system, and a corneal shape measurement optical system. The refractive power measurement optical system projects light onto a subject's eye via the objective lens and detects returning light from the subject's eye. The inspection optical system includes an optical scanner. The inspection optical system deflects light from a light source, projects the light deflected by the optical scanner onto the subject's eye via the objective lens, and detects returning light from the subject's eye. The corneal shape measurement optical system projects an arc-like or circumferential measurement pattern from an outer edge side of the objective lens onto the subject's eye and detects returning light from a cornea of the subject's eye. When a working distance is WD, a distance from a corneal apex of the subject's eye to a pupil of the subject's eye is d1, a distance from the pupil to a fundus of the subject's eye is d2, and a scan range by the optical scanner is SA square, a diameter of the objective lens is greater than or equal to ((WD+d1)×SA/d2).