Four-Mirror Refocusing Device for Straylight Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing refocusing devices for scientific observations in interferometers, such as those used in space applications, face challenges in minimizing the impact on focal path length and are prone to straylight, sensitivity to parasitic movements, and central obscuration.
Innovation Solution
A refocusing device comprising a base unit and a mirror unit with an even number of mirrors, specifically four or more, where at least one mirror is curved, allowing for minimal disturbance to the optical path and reducing sensitivity to parasitic movements, with a compact geometry that maintains co-linear input and output beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single lens, single mirror, or double mirror is used for refocusing, then the device complexity is reduced, but the measurement precision deteriorates due to straylight, sensitivity to parasitic movements, and central obscuration
Solution Approach 1:
The refocusing device is divided into multiple mirrors (at least four) arranged in a specific configuration rather than using a single optical element. This segmentation allows each mirror to contribute to the overall focusing function while reducing individual mirror size and eliminating central obscuration, thereby improving measurement precision for scientific observations.
2Measurement precision
If an even number of mirrors equal to four or more is used, then the measurement precision is improved by reducing straylight and sensitivity to parasitic movements, but the device complexity increases
Solution Approach 1:
The mirrors are arranged in an asymmetric configuration where at least one mirror is curved while others may be flat, and they are positioned at specific non-uniform intervals. This asymmetric design achieves the desired optical path folding and focusing effect while minimizing the number of mirrors to exactly four, balancing complexity reduction with precision improvement.
3Adaptability or versatility
If the mirror unit is made translatable parallel to the optical axis, then the adaptability is improved for focus adjustment, but the reliability deteriorates due to sensitivity to parasitic movements
Solution Approach 1:
The mirror unit is designed to translate only partially along the optical axis, with the translation distance limited to what is necessary for focus adjustment. The translation mechanism includes constraints that prevent excessive movement, and the optical design ensures that small parasitic movements do not significantly impact measurement reliability, achieving adaptability while maintaining stability.
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 solution provides a refocusing device that minimizes straylight and sensitivity to parasitic movements, maintaining stable optical path length and enabling precise focus adjustments, suitable for scientific observations and space applications.
Implementation Method 1
the mirror unit is configured to receive incident light along the optical axis in a first direction and to reflect the incident light parallel with the optical axis in said first direction
Implementation Method 2
The first mirror may be curved so as to provide optical power. In alternative embodiments, the second, third and/or fourth mirror may be curved. The curved mirror may be concave. Such a curvature and the resulting optical power may be small, for example in the order of F/50
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A focusing device (1) comprises a base unit (12) and a mirror unit (11) which is translatable relative to the base unit parallel to an optical axis (A) of the focusing device. The mirror unit (11) is configured to receive incident light along the optical axis (A) in a first direction and to reflect the incident light parallel with the optical axis (A) in said first direction. The mirror unit (11) comprises at least four mirrors (21-24), at least one of the mirrors being curved.