Off-Axial Three-Mirror Freeform Optical System Design
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Solution Overview
Problem
Conventional methods for designing optical systems with freeform surfaces are limited to small aperture and linear field-of-view systems, failing to effectively address aberrations and system complexity in off-axial three-mirror optical systems with larger apertures and wider field-of-views.
Innovation Solution
A method involving the selection of feature rays and point-by-point calculation of freeform surface equations using Snell's law to design off-axial three-mirror optical systems with freeform surfaces, allowing for the optimization of each surface to minimize optical path length and improve imaging quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rotationally symmetric surfaces are used in off-axial three-mirror optical systems, then the system structure is simpler to design, but aberrations increase and imaging quality deteriorates
Solution Approach 1:
The patent applies freeform surfaces with asymmetric profiles to the three-mirror optical system, replacing conventional rotationally symmetric surfaces. This asymmetry enables precise control of light paths in off-axial configurations, reducing aberrations and improving imaging quality while maintaining system performance for wide field-of-view applications
Solution Approach 2:
The patent implements freeform surfaces with locally optimized profiles on each mirror surface. By tailoring the surface geometry at different locations, the system achieves superior aberration correction and imaging performance across the entire field-of-view, particularly benefiting wide-angle and panoramic optical systems
2Manufacturing precision
If freeform surfaces are used in optical systems with small aperture, then aberrations are reduced and imaging quality improves, but the method cannot be effectively applied to systems with larger aperture and wider field-of-view
Solution Approach 1:
The patent employs a point-by-point design method that calculates freeform surface equations by controlling chief rays and marginal rays for multiple fields. This approach systematically adjusts surface parameters across the entire aperture, enabling effective application to large aperture and wide field-of-view systems while maintaining superior imaging quality and aberration control
Solution Approach 2:
The patent extends freeform surface design from two-dimensional rotational symmetry to three-dimensional asymmetric surfaces. By introducing additional geometric degrees of freedom in the surface profile, the method achieves effective aberration control for large aperture systems with wide fields-of-view, overcoming the limitations of conventional small-aperture designs
3Manufacturing precision
If more freeform surfaces are added to the optical system, then aberrations are further reduced and focus improves, but system complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies freeform surfaces selectively to specific mirror surfaces within the three-mirror system rather than all surfaces. This partial application achieves significant aberration reduction and focus improvement while avoiding the excessive complexity and manufacturing difficulties that would result from applying freeform surfaces to every surface in the system
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 method significantly reduces aberrations and improves imaging quality by allowing for the precise design of off-axial three-mirror optical systems with freeform surfaces, achieving better focus and smaller average RMS spot diameter with increasing numbers of freeform surfaces.
Implementation Method 1
Lights coming from the object space are successively reflected by the first freeform surface, the second freeform surface and the third freeform surface
Implementation Method 2
calculating a plurality of first feature data points point by point based on a given object-image relationship and Snell's law
Data Source
AI summary
A method for designing off-axial three-mirror optical system with freeform surfaces is provided. A first initial surface, a second initial surface, and a third initial surface are established. A plurality of feature rays are selected, while the first initial surface and the third initial surface remain unchanged; a plurality of first feature data points are calculated to obtain a third freeform surface equation by surface fitting the plurality of first feature data points. A third freeform surface and the second initial surface are remained unchanged; a plurality of second feature data points are calculated to obtain a first freeform surface equation by surface fitting the plurality of second feature data points. The third freeform surface and a first freeform surface are remained unchanged; a plurality of third feature data points are calculated to obtain a second freeform surface equation by surface fitting the plurality of third feature data points.