Offset Primary-Submirror Layout for Lightweight High-Gathering Optics
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Solution Overview
Problem
Existing optical systems for medium and large-size reflecting telescopes face challenges in achieving high light-gathering power while being cost-effective and lightweight, due to inefficient utilization of mirror areas and the need for precise curvature matching, leading to increased cost and weight.
Innovation Solution
An optical system comprising a primary mirror and a sub-mirror, where the sub-mirror is offset parallel to the primary mirror's edge, effectively utilizing the entire area of the cylindrical lens and reducing unnecessary portions, allowing for easy and inexpensive construction with a large light-gathering power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a parabolic reflecting mirror is used to achieve high light-gathering power, then the light-gathering power is improved, but the manufacturing cost and weight increase significantly
Solution Approach 1:
The optical system is divided into multiple segments: a primary mirror with a concave cylindrical surface and a sub-mirror with a convex cylindrical surface. Each mirror is curved only in one direction rather than requiring a complete parabolic shape, simplifying manufacturing while maintaining optical functionality through the combination of segments
Solution Approach 2:
The primary mirror and sub-mirror are each curved only in the direction needed to perform their specific optical function, rather than requiring complete parabolic curvature in all directions. This localized curvature approach reduces manufacturing complexity while achieving the desired light-gathering power
2Illumination intensity
If a large-size parabolic reflecting mirror is used, then the light-gathering power is improved, but the weight increases to several tons
Solution Approach 1:
The optical system splits the light-gathering function between a primary mirror and a sub-mirror, both of which can be made lighter than a single large parabolic mirror. The segmentation allows each component to be optimized for minimal weight while maintaining structural integrity
Solution Approach 2:
The mirrors can be constructed using thin-shell structures that are curved only in one direction, significantly reducing material usage and weight compared to traditional thick parabolic mirrors, while still maintaining the necessary optical properties
3Illumination intensity
If two concave-shaped reflecting bodies are arranged with opposed concave surfaces, then the light-gathering power is improved, but the manufacturing precision requirements increase
Solution Approach 1:
Each mirror is curved only in one direction (cylindrical curvature) rather than requiring complex two-directional parabolic curvature. This localized simplification of the surface geometry dramatically reduces manufacturing precision requirements while maintaining optical effectiveness
Solution Approach 2:
The system uses one concave cylindrical mirror and one convex cylindrical mirror with asymmetric curvatures optimized for their specific roles, rather than requiring two identical parabolic surfaces. This asymmetric design allows each component to be manufactured with simpler, less precise tolerances
4Device complexity
If the sub-mirror is positioned on the optical symmetry axis, then the optical path is simplified, but the mirror area utilization becomes inefficient
Solution Approach 1:
The sub-mirror is deliberately positioned asymmetrically, offset from the optical symmetry axis by a distance of 0.25f to 0.75f. This asymmetric positioning eliminates dead zones and improves area utilization of both mirrors while maintaining effective optical performance
Solution Approach 2:
Instead of positioning the sub-mirror only along the optical axis (one dimension), the invention introduces offset positioning in the lateral dimension. This two-dimensional positioning optimization allows both mirrors to utilize their full area effectively without creating unused zones
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 achieves a large light-gathering power with reduced material usage, facilitating weight reduction and simplified support structures, making it suitable for medium-size telescopes and compact, lightweight applications.
Implementation Method 1
a primary mirror (MH) having a concave-shaped reflecting surface 12 curved only in one direction, as shown in FIG. 2, and capable of reflecting light from an object (K)
Implementation Method 2
a sub-mirror (LH) disposed between the primary mirror (MH) and the linear focus of the primary mirror (MH), as shown in FIG. 2, and capable of transmitting light from the primary mirror (MH) or reflecting the light from the primary mirror (MH) to have a point focus
Implementation Method 3
capable of transmitting light from the primary mirror (MH) or reflecting the light from the primary mirror (MH)
Data Source
AI summary
Provided is an optical system having a configuration capable of attaining a large light-gathering power while producing a maximum light-gathering power easily and inexpensively with a minimum material. An offset optical system according to the present invention comprises: a primary mirror composed of at least part of one of two optical element halves obtained by dividing an optical element having a concave shape curved only in one direction, in an intermediate position of a length along a curvature thereof, wherein the optical element is configured to reflect and focus light from an object, into a linear focus; a sub-mirror disposed between the primary mirror and the linear focus and configured to transmit or reflect light reflected by the primary mirror, thereby focusing the light into a point focus; wherein, when: a direction tangent to the curvature in the intermediate position of the optical element is defined as an x-axis; a direction which is perpendicular to the x-axis and in which the object is located is defined as a y-axis; and a direction orthogonal to the x-axis and the y-axis is defined as a z-axis, the sub-mirror is offset parallel to the x-axis by a given distance toward an edge of the primary mirror located distal to the y-axis.