Freeform Off-Axis Three-Mirror Imaging System
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Solution Overview
Problem
Current imaging optical systems face a trade-off between achieving a larger field of view and higher resolution, as increasing one typically decreases the other, making it difficult to design systems with both enhanced observation range and improved resolution simultaneously.
Innovation Solution
The design incorporates a freeform surface off-axis three-reflecting mirror optical system with a specific configuration of primary, secondary, and tertiary reflecting mirrors, along with an aperture stop, which allows for a larger field of view and focal length while maintaining a consistent F-number across the field of view, thereby achieving improved resolution and observation range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focal length is increased to improve resolution, then the resolution rate increases, but the field of view decreases
Solution Approach 1:
The patent transitions from a conventional single-lens imaging system to a three-dimensional freeform off-axis three-reflecting mirror system. By utilizing multiple reflection surfaces arranged in three-dimensional space, the system achieves both a large field of view (40 degrees) and high resolution simultaneously, breaking the traditional two-dimensional trade-off constraint between focal length and field of view.
Solution Approach 2:
The imaging system is divided into three separate reflecting mirrors (primary, secondary, and tertiary) with distinct functions. Each mirror segment handles specific portions of the optical path, allowing independent optimization of each surface to achieve both wide field coverage and high resolution across the entire field of view.
2Area of moving object
If the field of view is increased to expand observation range, then the observation range increases, but the resolution rate decreases
Solution Approach 1:
Each reflecting mirror surface is designed with locally optimized freeform characteristics tailored to its specific function in the optical path. The primary mirror captures wide-angle light, the secondary mirror redirects it, and the tertiary mirror focuses it, with each surface having customized local properties to maintain high resolution across the entire 40-degree field of view.
Solution Approach 2:
The system uses three-dimensional freeform surfaces instead of conventional two-dimensional rotational symmetric surfaces. This dimensional transition allows the mirrors to manipulate light rays from different field angles independently, achieving uniform high resolution across a wide field of view that would be impossible with traditional lens systems.
3Device complexity
If a conventional lens system is used, then the structure is simple, but it is difficult to achieve both large field of view and high resolution simultaneously
Solution Approach 1:
The patent replaces the conventional refractive lens system with a reflective mirror system. By using reflection instead of refraction, the system eliminates chromatic aberration and achieves higher resolution. The freeform reflective surfaces provide precise control over light paths, enabling simultaneous achievement of wide field of view and high resolution that conventional lenses cannot achieve.
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 configuration results in an imaging optical system with twice the focal length and effective aperture at the center compared to the edges, maintaining a consistent F-number and achieving high imaging quality, effectively addressing the trade-off between field of view and resolution.
Implementation Method 1
The light from the object enters the primary reflecting mirror (102) and is reflected on the primary reflecting mirror (102), to form a first reflected light beam
Implementation Method 2
The first reflected light beam irradiates the secondary reflecting mirror (104) and is reflected, to form a second reflected light beam
Implementation Method 3
The second reflected light beam irradiates the tertiary reflecting mirror (106) and is reflected, to form a third reflected light beam, and the third reflected light beam reaches an image surface (110) for imaging
Data Source
AI summary
An imaging optical system includes a primary reflecting mirror, a secondary reflecting mirror, a tertiary reflecting mirror, and an aperture stop. The imaging optical system has a field of view, a focal length of the field of view that is defined as FFL, and an effective aperture of a field of view entrance pupil that is defined as FEPD. The FFL and the FEPD at a central field of view are greater than that at the edge field of views, and the FFL and the FEPD change continuously.