Relay Lens System Using Different Materials for Chromatic Aberration
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Solution Overview
Problem
Current optical lens systems for endoscopes face challenges in maintaining image quality across a broad wavelength range, particularly in visible and near-infrared regions, due to chromatic aberrations caused by dispersion, which is exacerbated by the need for a single image sensor to focus all light onto one plane.
Innovation Solution
The use of relay rods made of different materials, symmetrically positioned relative to the pupil, to compensate for residual wavefront error and dispersion, while maintaining the same design and configuration of powered elements, thereby correcting axial chromatic aberration without increasing system complexity or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If relay rods made of the same material are used, then the system is simpler to manufacture, but chromatic aberrations and wavefront error increase across the broadband wavelength range
Solution Approach 1:
The patent applies composite materials by using relay rods made of different materials (e.g., glass types with different Abbe numbers) in a symmetric configuration. This composite approach compensates for chromatic aberrations and wavefront error across the broadband wavelength range (460 nm to 850 nm) while maintaining manufacturing feasibility through standardized rod components.
Solution Approach 2:
The patent implements local quality by assigning different material properties to different relay rods based on their position in the optical system. The first and third relay rods use one material while the second and fourth relay rods use a different material, creating localized material variations that correct chromatic aberrations in specific regions of the broadband spectrum.
2Device complexity
If a single image sensor is used to detect all wavelengths, then the system structure is simplified, but axial chromatic aberration increases due to the need to focus all light onto one plane
Solution Approach 1:
The patent applies parameter changes by modifying the refractive index parameters of the relay rod materials to compensate for chromatic aberrations. By selecting materials with specific Abbe numbers and refractive indices, the system achieves diffraction-limited performance across the broadband wavelength range while maintaining a single image sensor configuration.
Solution Approach 2:
The patent uses composite materials with different dispersion properties to correct axial chromatic aberration in the single-sensor system. The symmetric arrangement of relay rods made from different glass types creates compensatory effects that enable sharp focus across the 460 nm to 850 nm spectrum on a single detector plane.
3Manufacturing precision
If relay rods with different materials are used, then chromatic aberrations are reduced, but the system complexity and material selection requirements increase
Solution Approach 1:
The patent applies asymmetry in material selection while maintaining geometric symmetry in the relay rod arrangement. Different glass types with specific Abbe number relationships are chosen to create asymmetric dispersion compensation, reducing chromatic aberrations while preserving the symmetric optical path for simplified alignment.
Solution Approach 2:
The patent implements local quality by assigning specific material properties to specific relay rod positions. The first and third relay rods use one material while the second and fourth relay rods use a different material, creating localized material variations that correct chromatic aberrations in specific regions of the broadband spectrum.
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 significantly improves the modulation transfer function (MTF) for transverse off-axis rays, ensuring high-resolution imaging across the 460 nm to 850 nm wavelength range with reduced wavefront error and chromatic aberrations, enhancing the overall image quality.
Implementation Method 1
The first and second materials may be selected to reduce the wavefront error across the field of view of the optical system as compared with using a same material for both the first and second relay rods
Implementation Method 2
compensate for residual wavefront error and dispersion, while maintaining the same design and configuration of powered elements, thereby correcting axial chromatic aberration
Data Source
AI summary
An optical system includes a first relay rod of a first material, a second relay rod of a second material, different from the first material, and a lens between the first and second relay rods.