Multi-Channel Telescope with Shared Primary Mirror and Spectral Splitter
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Solution Overview
Problem
Existing multi-channel telescopes require additional re-imaging optics for each spectral band, increasing complexity, size, mass, and cost, which is detrimental for satellite installations and degrades image quality due to chromatic aberrations, especially when large pupils are needed.
Innovation Solution
A telescope design with a primary mirror and two re-imaging assemblies, each with a secondary and tertiary mirror, where a spectral separation device is placed between the primary and secondary mirrors to separate radiation into different spectral bands, eliminating the need for additional re-imaging optics and allowing each telescope to adapt magnification independently for its image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional re-imaging optics are added for each spectral band, then image quality is maintained, but device complexity, size, and mass increase significantly
Solution Approach 1:
The optical system is segmented into multiple independent optical paths (first optical path for thermal infrared, second optical path for SWIR/NIR, third optical path for visible) that share common upstream components (primary mirror, spectral separation device) but have separate downstream re-imaging assemblies and image sensors. This allows each spectral band to be optimized independently while sharing the telescope structure.
Solution Approach 2:
The primary mirror and spectral separation device serve multiple functions: they are shared across all three optical paths, reducing the total number of components. The re-imaging assemblies are designed to be adaptable to different image sensor requirements, providing universal functionality across different spectral bands.
2Adaptability or versatility
If additional re-imaging optics are added for each spectral band, then magnification can be adapted to image sensor requirements, but size and mass of the instrument increase
Solution Approach 1:
The system divides the optical paths into segments that share common components upstream and have independent re-imaging assemblies downstream. This segmentation allows each spectral band to have customized magnification while sharing the heavy primary mirror and spectral separation device, reducing overall mass.
Solution Approach 2:
The re-imaging assemblies are nested within the overall telescope structure, with each assembly containing secondary and tertiary mirrors that fit within the spatial envelope defined by the primary mirror. This nested arrangement optimizes space utilization and reduces the overall instrument size.
3Adaptability or versatility
If dioptric elements are used in re-imaging optics, then magnification can be adjusted, but chromatic aberration degrades image quality
Solution Approach 1:
The system replaces dioptric (lens-based) elements with catoptric (mirror-based) re-imaging assemblies. Mirrors reflect all wavelengths equally, eliminating chromatic aberration while still providing the necessary magnification adjustment through geometric optical design of the secondary and tertiary mirrors.
4Adaptability or versatility
If separate re-imaging optics are provided for all spectral bands, then each optical path can be optimized, but cost increases
Solution Approach 1:
The optical system is segmented into paths that share common expensive components (primary mirror, spectral separation device) while having separate, simpler re-imaging assemblies for each spectral band. This reduces overall cost by eliminating redundancy in the upstream components.
Solution Approach 2:
The primary mirror and spectral separation device serve multiple spectral bands simultaneously, providing universal functionality that reduces the total number of components needed. Each re-imaging assembly is designed to be adaptable to different image sensor requirements, providing cost-effective optimization for each band.
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 design reduces the number of components, size, and mass while maintaining image quality by allowing separate magnification adjustments for each spectral band, avoiding chromatic aberrations and stray light, and enabling efficient radiation separation without additional re-imaging optics.
Implementation Method 1
a spectral separation device, which is adapted to direct, along a first direction of emergence, a portion of the radiation belonging to one of the two spectral bands selectively with respect to another portion of the radiation belonging to a second of the two spectral bands
Implementation Method 2
a primary mirror, of concave type, which has a focal length value and which is adapted to form an intermediate image of a content of the input optical field
Implementation Method 3
a primary mirror, of concave type, which has a focal length value and which is adapted to form an intermediate image
Implementation Method 4
the first useful image being optically conjugated with the intermediate image by the first secondary mirror and the first tertiary mirror
Data Source
Figure 1~2
Figure 3a
Figure 3b
AI summary
A multi-way optical instrument with telescope function comprises two telescopes sharing a common primary mirror (M1). Each telescope has a secondary mirror (M2TIR, M2SWIR-VIS) and a tertiary mirror (M2TIR, M2SWIR-VIS) that differ from those of the other telescope, forming two separate optical paths downstream of the common primary mirror. These two optical paths can be dedicated to respective spectral bands by a spectral splitter (40) located near an intermediate image formed by the primary mirror.