Gradient Index Lens Optical System for Miniaturized Endoscope
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Solution Overview
Problem
Existing optical systems for rigid endoscopes face challenges in reducing diameter while maintaining image quality, as conventional relay lens systems are difficult to miniaturize and gradient index lenses have limitations in correcting chromatic aberration for small diameter scopes.
Innovation Solution
The optical system employs a plurality of lenses with refractive index distributions changing orthogonal to their optical axes, positioned on the same straight line, manufactured to share the same design values and refractive index distribution constants, with specific rotation positions to minimize total aberration, allowing for a coaxial arrangement that reduces wavefront aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a relay lens optical system is used to achieve superior image quality, then image quality is improved, but the diameter of the optical system cannot be reduced
Solution Approach 1:
The optical system is divided into multiple gradient index lenses with different refractive index distributions. Each lens segment contributes to correcting specific aberrations, allowing the system to achieve high image quality while maintaining a compact diameter that would be impossible with a conventional relay lens system
2Area of stationary object
If the diameter of the optical system is reduced for a rigid scope, then the outer diameter of the insertion part is reduced, but chromatic aberration correction becomes insufficient
Solution Approach 1:
Each gradient index lens is designed with a specific refractive index distribution tailored to its position in the optical system. The first lens has a distribution optimized for its function, while the second lens has a different distribution to complement it. This local optimization of optical properties allows effective chromatic aberration correction in a compact diameter
Solution Approach 2:
The optical system uses composite lens structures combining gradient index lenses with different refractive index profiles. This composite approach enables the system to correct chromatic aberration effectively while maintaining a small diameter, achieving performance that neither lens type could achieve alone
3Area of stationary object
If multiple gradient index lenses are arranged coaxially to reduce diameter, then the outer diameter is reduced, but wavefront aberration increases
Solution Approach 1:
The refractive index distribution parameters of each gradient index lens are carefully optimized and differentiated. The first lens has a specific refractive index distribution constant, while the second lens has a different constant. This parameter differentiation allows the coaxial arrangement to reduce diameter while the specific parameter combinations cancel out wavefront aberrations rather than accumulate them
Data Source
AI summary
An optical system includes a plurality of lenses. The plurality of lenses have refractive index distributions in which a refractive index changes in directions orthogonal to optical axes. The optical axes of the plurality of lenses are disposed on the same straight line as each other. The plurality of lenses are manufactured on the basis of same design values relating to an on-axis refractive index and a refractive index distribution constant. When rotation positions around the optical axes of the plurality of lenses at which a total aberration amount of the plurality of lenses reaches a maximum are set as reference rotation positions for the plurality of lenses, any one of the plurality of lenses is arranged at a position acquired by relatively rotating the reference rotation position around the optical axis.