Catadioptric Optical System with Total Internal Reflection
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Solution Overview
Problem
Conventional catadioptric optical systems face challenges in achieving high numerical aperture values while minimizing obscuration, correcting chromatic aberration and Petzval curvature, and ensuring easy alignment, which degrades image quality and increases complexity.
Innovation Solution
A catadioptric optical system design featuring a first and second catadioptric unit with a lens group, utilizing total internal reflection and carefully aligned reflective and transmissive surfaces to minimize obscuration and aberrations, and facilitate alignment, with a configuration that cancels outward and inward Petzval curvatures and chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional catadioptric optical systems use reflective and refractive elements to achieve high numerical aperture, then the NA value can be increased, but obscuration increases and image quality degrades
Solution Approach 1:
The optical system is divided into multiple discrete optical elements including a meniscus lens, a Mangin mirror, and additional lens elements. Each element is optimized to perform specific functions: the meniscus lens provides initial convergence, the Mangin mirror provides reflection and refraction with controlled obscuration, and subsequent lens elements correct aberrations. This segmentation allows the system to achieve high NA while managing obscuration through careful design of each component's geometry and positioning.
2Force
If conventional designs increase the marginal ray angle to achieve high NA, then the NA value increases, but optical aberrations increase and require significantly complicated optical arrangements
Solution Approach 1:
The system employs specific parameter optimizations including the meniscus lens with curvature radii ratio between 0.5 and 2.0, the Mangin mirror with curvature radius ratio between 0.3 and 0.7, and refractive index ratios between 1.3 and 1.7. These parameter ranges are carefully selected to achieve high NA while controlling aberrations. The conditional expressions ensure that the optical system maintains proper balance between convergence power and aberration control, avoiding the need for excessively complicated arrangements.
3Manufacturing precision
If conventional catadioptric systems use multiple optical elements to correct aberrations, then image quality improves, but alignment difficulty increases
Solution Approach 1:
The optical design incorporates preliminary correction of aberrations through the specific configuration of the meniscus lens and Mangin mirror combination. By pre-designing the curvature radii ratios and refractive index relationships, the system anticipates and compensates for potential misalignment effects. The conditional expressions ensure that the system maintains robust aberration correction even with minor alignment variations, reducing the sensitivity to alignment errors and simplifying the alignment process.
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 design achieves high numerical aperture values with reduced obscuration, improved image contrast, and simplified alignment, resulting in enhanced image quality and system compactness.
Implementation Method 1
utilizing total internal reflection and carefully aligned reflective and transmissive surfaces
Data Source
AI summary
A catadioptric optical system includes, in order from an object side to an image side and arranged along an optical axis, a first catadioptric unit, a second catadioptric unit disposed in axial alignment with the first catadioptric unit and with a space therebetween; and a lens group disposed in axial alignment with the first and second catadioptric optical units. Light rays arriving from an object plane undergo a first reflection at the image-side surface of the first catadioptric optical unit, a second reflection at the object-side surface of the first catadioptric optical unit, a third reflection at the image-side surface of the second catadioptric optical unit, and a fourth reflection at the object-side surface of the second catadioptric optical unit. Advantageously, the sum the outward Petzval curvatures is cancelled out by the sum of inward Petzval curvatures.