Catadioptric Multi-Reflection Element for High NA Imaging
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Solution Overview
Problem
Conventional catadioptric optical systems face challenges with high obscuration ratios, limited numerical aperture, and complex fabrication due to the need for precise alignment and correction of chromatic aberrations and Petzval curvature, especially in high-numerical-aperture applications.
Innovation Solution
A catadioptric system comprising a first and second catadioptric group and a lens group in axial alignment, featuring a multi-reflection optical element with a solid lens that undergoes more than two reflections, providing a continuous and smooth topological profile for easy fabrication and minimizing obscuration while correcting aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional catadioptric systems use multiple optical elements to correct aberrations, then image quality is improved, but device complexity and total length increase
Solution Approach 1:
The patent combines multiple optical functions into a single integrated optical element. This element incorporates both refractive and reflective properties, allowing it to perform the functions of multiple separate optical elements while correcting aberrations and controlling obscuration in one component.
Solution Approach 2:
The single optical element is designed to perform multiple functions simultaneously: it acts as both a refractive and reflective element, corrects various aberrations, controls obscuration ratio, and manages Petzval curvature. This multi-functionality eliminates the need for separate dedicated components for each function.
2Reliability
If conventional catadioptric systems use reflective elements to control chromatic aberrations, then chromatic aberration is reduced, but central obscuration and Petzval curvature increase
Solution Approach 1:
The optical element features non-uniform refractive index distribution and varied surface curvatures in different regions. The refractive index changes locally to control light paths and aberrations, while different zones of the element have optimized surface properties to minimize obscuration and Petzval curvature effects.
Solution Approach 2:
The patent employs optical materials with composite or gradient refractive index structures. These materials combine the benefits of refractive and reflective properties in a single element, allowing simultaneous control of chromatic aberration, obscuration, and Petzval curvature through the material's optical properties rather than relying on separate reflective surfaces.
3Reliability
If the first optical element reflects light more than two times within it, then aberrations are corrected, but fabrication complexity and cost increase
Solution Approach 1:
The patent optimizes parameters such as the number of reflections (more than two), surface curvatures, refractive index gradients, and thickness distributions to achieve aberration correction. By carefully selecting and adjusting these parameters, the design achieves good optical performance while keeping fabrication within reasonable tolerances.
Solution Approach 2:
The optical element incorporates curved surfaces with specific radius of curvature values that facilitate multiple reflections. These curved geometries are designed to be manufacturable using conventional optical fabrication techniques, balancing the need for precise curvature with practical manufacturing capabilities.
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 solution achieves a reduced obscuration ratio, improved field of view, and minimized RMS wavefront errors across a broad spectral band, enabling easier alignment and maintaining image quality with fewer optical elements.
Implementation Method 1
A light flux entering through the input surface undergoes more than two reflections between the primary and secondary reflective surfaces, prior to exiting through the exit surface
Data Source
AI summary
A catadioptric system includes a first catadioptric group, a second catadioptric group, and a lens group disposed in axial alignment with each other. The first catadioptric group includes a solid lens having an input surface, a primary reflective surface, secondary reflective surface and an exit surface. The primary reflective surface is a curved surface concave towards the secondary reflective surface. A light flux entering through the input surface undergoes more than two reflections between the primary and secondary reflective surfaces, prior to exiting through the exit surface. At least one of the primary reflective surface and secondary reflective surface has a continuous and smooth topological profile.