Freeform Surface Design via Feature Ray Intersections
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Solution Overview
Problem
Conventional methods for designing freeform optical surfaces primarily focus on two-dimensional contours and are limited to small aperture and linear field-of-view optical systems, failing to effectively address the design requirements of larger, off-axis asymmetric systems.
Innovation Solution
A method involving point-by-point construction of freeform surfaces using feature rays, where intersections with an initial surface and adjacent surfaces are calculated to determine feature data points, allowing for the derivation of a freeform surface equation, and incorporating Snell's law to optimize the surface design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional two-dimensional contour methods are used for designing freeform surfaces, then the design process is simpler, but the applicability is limited to small aperture and linear field-of-view systems only
Solution Approach 1:
The patent segments the freeform surface design into discrete data points along the optical axis, where each point is determined by intersecting feature rays with the surface. This point-by-point construction method transforms the continuous surface design problem into a series of discrete calculations, enabling extension from 2D contours to full 3D freeform surfaces for off-axis asymmetric systems
Solution Approach 2:
The patent transitions from two-dimensional contour design to three-dimensional freeform surface design by introducing the optical axis dimension. Feature rays are traced through 3D space and intersected with the initial surface at multiple axial positions, creating a point cloud that defines the complete 3D freeform geometry, thus adding the third dimension to the design process
2Adaptability or versatility
If point-by-point construction with feature rays is used, then three-dimensional freeform surfaces for large aperture systems can be designed, but computational complexity increases
Solution Approach 1:
The patent performs preliminary ray tracing calculations to determine the intersections of feature rays with the initial surface before final surface fitting. By pre-calculating these intersection points and organizing them systematically along the optical axis, the method prepares the data structure in advance, reducing the computational burden during the actual freeform surface generation and optimization phases
Solution Approach 2:
The patent introduces an initial surface as an intermediary element between the object space and the final freeform surface. Feature rays are first traced to intersect with this initial surface to generate data points, which then serve as the foundation for constructing the final freeform surface. This intermediary approach simplifies the complex direct calculation by providing a reference framework
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 enables the design of three-dimensional freeform surfaces suitable for off-axis asymmetric systems with larger apertures and multi-field imaging, reducing computational complexity and expanding the applicability to various optical systems beyond conventional limitations.
Implementation Method 1
calculating a plurality of intersections of a plurality of feature rays Ri (i=1, 2 . . . K) with an unknown freeform surface based on a given object-image relationship and Snell's law
Data Source
AI summary
A method for designing freeform surface is provided. An initial surface is established. A plurality of feature rays are selected. A plurality of intersections of the plurality of feature rays with an unknown freeform surface are calculated based on a given object-image relationship and a vector form of the Snell's law. The plurality of intersections are a plurality of feature data points. An unknown freeform surface equation is obtained by surface fitting the plurality of feature data points.