Freeform Imaging System Design Using Feature Rays
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Solution Overview
Problem
Traditional freeform imaging system design methods often start with spherical or aspherical systems, which limit the degrees of freedom and result in aberrations, making it difficult to achieve a wide linear field-of-view with optimal image quality.
Innovation Solution
A design method for freeform imaging systems that iteratively constructs and refines freeform surfaces using feature rays and the Nearest-ray Principle, based on the object-image relationship, to redirect light rays effectively and minimize optical path length, allowing for the creation of surfaces that improve image quality through multiple iterations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If spherical or aspherical systems are used as the starting point for freeform imaging system design, then the design process is simpler and more conventional, but the degrees of freedom are limited and aberrations increase
Solution Approach 1:
The patent applies asymmetry by replacing traditional rotationally symmetric surfaces with freeform surfaces that have different curvatures in different directions. This allows the optical system to achieve wider field-of-view and better aberration control by eliminating the constraints of rotational symmetry, enabling each surface point to have optimized local properties
Solution Approach 2:
The patent transitions from conventional 2D rotational symmetry to 3D freeform surfaces by introducing additional degrees of freedom in the surface profile. This dimensional expansion allows the optical surfaces to manipulate light rays more effectively across wide angles while maintaining image quality
2Ease of operation
If traditional freeform imaging system design methods are used, then the design process follows conventional steps, but it is difficult to achieve wide linear field-of-view with optimal image quality
Solution Approach 1:
The patent applies local quality by optimizing each region of the optical surface independently to handle different field angles. The freeform surfaces are designed with locally varying curvatures and orientations that are specifically tailored to correct aberrations at different positions in the wide field-of-view, rather than using a uniform surface design
3Manufacturing precision
If freeform surfaces are used to increase degrees of freedom, then aberrations are reduced and image quality is improved, but the system structure becomes more complex
Solution Approach 1:
The patent extracts and concentrates the complexity into the surface profiles themselves rather than requiring additional optical elements. By embedding the necessary aberration correction directly in the freeform surface geometry, the system achieves high image quality with fewer components compared to traditional designs that would require multiple lenses or mirrors
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 method significantly reduces aberrations and simplifies the system structure, achieving rapid convergence and improved image quality, with spot sizes converging to a steady value and standard deviation indicating consistent improvement across sampling fields.
Implementation Method 1
A freeform imaging system comprises a first surface and a second surface spaced from each other. A plurality of light rays from an object are redirected by the first surface and the second surface, and focus on an image plane to form a plurality of ideal image points.
Data Source
AI summary
A design method of freeform imaging system is provided. An initial freeform imaging system is provided, the initial freeform image system comprising a first initial surface and a second initial surface spaced from each other. A second surface is constructed by calculating a plurality of second data points of the second surface through a plurality of feature rays based on the given object-image relationship. A first surface is constructed by calculating a plurality of first data points of the first surface based on the given object-image relationship and Fermat's principle, wherein the second surface is fixed. The first surface and the second surface substitute for the first initial surface and second initial surface respectively, and repeating steps list above, wherein the plurality of feature rays are intersecting the image plane at the plurality of ideal image points.