All-Reflective Afocal Four-Mirror Telescope Design
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Solution Overview
Problem
Conventional optical systems require different telescopes for focal and afocal imaging tasks, lacking an all-reflective system that can seamlessly provide both functions.
Innovation Solution
An all-reflective optical system is designed with a specific configuration including a positive-powered primary mirror, negative-powered secondary mirror, and higher-order aspheric tertiary and quaternary mirrors with de-centers and tilts, along with fold and beam steering mirrors to achieve afocal functionality while sharing the first two mirrors of a focal three-mirror anastigmat system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different telescopes are used for focal and afocal imaging tasks, then imaging performance for specific tasks is optimized, but system complexity and the number of required devices increase
Solution Approach 1:
The patent applies multi-functionality by designing a single all-reflective optical system that can operate in both focal and afocal modes. The system uses a primary mirror, secondary mirror, tertiary mirror, and optional fourth mirror that can be configured to provide either focal plane imaging or afocal collimated output, eliminating the need for separate telescopes for different imaging tasks.
Solution Approach 2:
The patent employs dynamic configuration by making the optical system adjustable between focal and afocal modes. The presence of optional fold mirrors and a beam steering mirror allows the system to dynamically change its optical path and output characteristics based on the required imaging task, providing adaptability without requiring multiple fixed systems.
2Adaptability or versatility
If an all-reflective system provides both focal and afocal functions, then versatility is improved, but optical design complexity increases
Solution Approach 1:
The patent segments the optical system into distinct functional modules: a core all-reflective optical system with primary, secondary, and tertiary mirrors that provides both focal and afocal capabilities, and optional auxiliary components (fold mirrors, beam steering mirror) that can be added or removed based on specific application requirements. This modular segmentation manages design complexity while maintaining versatility.
Solution Approach 2:
The patent uses fold mirrors and beam steering mirrors as intermediary elements that enable the optical system to switch between focal and afocal configurations. These intermediary components facilitate the transition between modes by redirecting light paths without requiring fundamental changes to the core optical design, thereby managing complexity while achieving adaptability.
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 system effectively provides high-performance afocal optical functions while maintaining the optimality of the first two mirrors for focal three-mirror anastigmat systems, correcting aberrations and achieving flat-field conditions over a desired field-of-view.
Implementation Method 1
a positive-powered primary mirror, which receives a plurality of incoming light rays and reflects the light rays onto a negative-powered secondary mirror
Implementation Method 2
a negative-powered secondary mirror positioned behind the primary mirror and configured to receive the light rays reflected from the primary mirror and reflect the light rays onto a positive-powered tertiary mirror
Implementation Method 3
a positive-powered tertiary mirror configured to receive the light rays reflected from the secondary mirror and reflect and collimate the light rays to a common convergence point
Data Source
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AI summary
An all-reflective optical system (100, 200, 300, 400) includes a primary mirror (110, 210) of ellipsoidal configuration, a secondary mirror (120, 220) of hyperboloidal configuration facing the primary mirror, and an eye-piece (160, 260) that includes: a positive-powered tertiary mirror (130, 230) having a majority of positive power that is expected in the eye-piece and configured to substantially collimate light rays incident thereon; and a negative-powered near-flat quaternary mirror (140, 240) having lesser power than the tertiary mirror and configured to receive the substantially collimated light rays from the tertiary mirror, further collimate the received light rays and reflect the further collimated light rays to an exit pupil (150). The primary mirror, the secondary mirror and the eye-piece thereby form an afocal optical system.