Bifocal Anastigmatic Telescope with Retractable Mirrors
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Solution Overview
Problem
Current space telescopes with a Korsch architecture cannot achieve a bifocal anastigmatic solution for two different focal lengths using the same combination of mirrors, requiring additional components and mirror movement to change focal lengths, which complicates the system and reduces efficiency.
Innovation Solution
A bifocal anastigmatic telescope with five aspherical mirrors, where two additional retractable mirrors are positioned on the optical path for each focal length, allowing the telescope to maintain a common detector and optimal image quality without moving existing mirrors, using generalized Korsch equations to determine mirror positions and forms for both focal lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Korsch telescope with 3 mirrors is used, then the telescope achieves good image quality over a large field with compact design, but it cannot achieve bifocal anastigmatic solution for two different focal lengths
Solution Approach 1:
The optical system is segmented into two distinct mirror combinations: a first combination of three mirrors (M1, M2, M3) for the first focal length, and a second combination that includes four mirrors (M1, M2, M3, M4) for the second focal length. This segmentation allows each mirror combination to be independently optimized for its specific focal length while sharing common components (M1, M2, M3), thereby achieving bifocal capability without proportionally increasing overall system complexity.
Solution Approach 2:
Mirrors M1, M2, and M3 serve dual functions: they form part of the first mirror combination for the first focal length and also form part of the second mirror combination for the second focal length. This multi-functionality allows the telescope to achieve two different focal lengths using a shared set of mirrors, reducing the total number of mirrors needed compared to having completely separate optical systems for each focal length.
2Adaptability or versatility
If additional mirrors are added to achieve bifocal capability, then the telescope can operate at two focal lengths, but the system complexity and number of components increases
Solution Approach 1:
The mirror system is segmented into a core set of three mirrors (M1, M2, M3) that are common to both focal lengths, and an additional mirror (M4) that is specific to the second focal length. This segmentation strategy minimizes the total number of mirrors by maximizing the shared components between the two focal length configurations.
Solution Approach 2:
The first three mirrors (M1, M2, M3) are designed to be universal, serving both the first focal length configuration (alone) and the second focal length configuration (in combination with M4). This multi-functionality reduces the total mirror count from what would be required if completely separate mirror systems were used for each focal length.
3Adaptability or versatility
If the focal length is changed by moving mirrors, then the bifocal function is achieved, but the reliability and image quality may be compromised due to mirror movement
Solution Approach 1:
The patent employs movable or retractable mirrors (specifically M3 and/or M4) that can be dynamically positioned to switch between the first and second focal length configurations. This dynamic adjustment capability allows the telescope to change focal length while maintaining stable, high-quality images by precisely controlling mirror positions rather than using fixed, compromised optical paths.
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
Enables efficient switching between two focal lengths without moving existing mirrors, maintaining compactness and image quality, and allowing for simultaneous operation with a common field of view and detector, while minimizing wavefront error and chromatic aberration.
Implementation Method 1
a bifocal anastigmatic telescope with five aspherical mirrors... the first mirror and the second mirror form, from an object at infinity, an intermediate image... the third mirror forming, from this intermediate image, a final image in the focal plane
Data Source
AI summary
A bifocal anastigmatic telescope with five aspherical mirrors, comprises: a concave first mirror, a convex second mirror, a concave third mirror and a first detector, which are common to a first and second focal length of the telescope, a first fourth mirror and a first fifth mirror that are associated with the first focal length, and a second fourth mirror and a second fifth mirror that are associated with the second focal length, the first mirror and the second mirror being arranged to form, from an object at infinity, an intermediate image situated between the second mirror and the third mirror, and for each focal length: the fixed positions and forms of the mirrors associated with the focal length being determined from the generalized Korsch equations with 5 mirrors, with the constraint of the first, second and third mirror and of the first focal plane that are common to the two focal lengths, and so as to optimize the image quality in the first focal plane of the telescope in accordance with a predetermined criterion.