Optical Module Aberration Correction via Lens Segmentation
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Solution Overview
Problem
Conventional eyepieces, such as the Ramsden eyepiece, face challenges in achieving diffraction-limited imaging across a wide range of system parameters due to residual aberrations, particularly in terms of spherical aberration and distortion, which affect the optical performance and field height.
Innovation Solution
A modified optical module comprising three or four lenses, where the additional lenses correct residual aberrations of the classic Ramsden eyepiece, with specific constraints on effective focal lengths and airspaces between lenses to achieve diffraction-limited performance, ensuring a peak-valley wavefront of no larger than 0.25 waves at any field point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a classic Ramsden eyepiece with two plano-convex lenses is used, then the structure is simple and easy to manufacture, but residual spherical aberration and distortion remain that prevent diffraction-limited imaging
Solution Approach 1:
The classic two-lens Ramsden eyepiece is segmented into three or four lens elements. The additional lens elements are specifically designed to correct residual aberrations (spherical aberration and distortion) that cannot be eliminated by the simple two-lens configuration, while maintaining relative structural simplicity for manufacturability.
Solution Approach 2:
The patent employs composite lens structures where multiple lens elements with different optical properties (positive and negative focal lengths) are combined. This composite approach allows the system to achieve diffraction-limited imaging by compensating for aberrations through the interaction of different lens components.
2Manufacturing precision
If additional lens elements are added to correct residual aberrations, then imaging precision improves to achieve diffraction-limited performance, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning specific optical characteristics to specific lens positions. The first and second lens elements have positive focal lengths while the third has a negative focal length, with each element optimized for its local function in the optical path. This localized optimization achieves global aberration correction without requiring complete redesign of the entire system.
Solution Approach 2:
The patent utilizes parameter changes by varying the focal lengths, spacing distances, and optical powers of individual lens elements. Specific relationships are established (e.g., EFL1 and EFL2 between 1.5-3.0 times EFLsys, EFL3 between -8.0 to -4.0 times EFLsys) to achieve diffraction-limited performance while controlling overall system complexity.
3Length of moving object
If lens elements are positioned closer together to reduce size, then compactness improves, but aberration correction capability deteriorates
Solution Approach 1:
The patent establishes dynamic spacing relationships between lens elements rather than fixed positions. The air distances A12 and A23 are defined as fractions of the system focal length EFLsys (A12: 0.05-0.50×EFLsys, A23: 0.05-0.30×EFLsys), allowing the optical system to maintain aberration correction capability while adapting to different size requirements through proportional scaling.
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 optical module enhances optical performance by reducing spherical aberration and distortion, achieving diffraction-limited imaging across a wide range of parameters, improving the overall imaging quality and field height, as demonstrated by specific embodiments with reduced peak-valley wavefront compared to classic Ramsden eyepieces.
Implementation Method 1
The optical module includes at least three lens elements with specific effective focal lengths and air-distances that satisfy predetermined relationships, configured to correct residual aberrations and achieve diffraction-limited imaging
Data Source
AI summary
An optical module comprising: at least three lens elements, wherein the lens elements collectively set a numerical aperture NA, a field height FH, and a system effective focal length EFLsys for directing the light rays between first and second planes, wherein NA, FH, and EFLsys satisfy 0<NA<0.25 and 0<FH<(0.4)·(EFLsys); wherein first and second adjacent lens elements having effective focal lengths EFL1 and EFL2, respectively, satisfies (1.5)·(EFLsys)<EFL1<3·(EFLsys) and (1.5)·(EFLsys)<EFL2<3·(EFLsys); wherein an air-distance between the first and second lens elements A12 satisfies 0<A12<EFLsys; wherein a third lens element adjacent the second lens elements opposite the first lens element and having an effective focal length EFL3 satisfies (−20)·EFLsys<EFL3<(−1)·EFLsys; and wherein an air-distance between the second and third lens elements A23 satisfies 0<A23<EFLsys.