Reflective Telecentric Relay for Airborne Hyperspectral Imaging
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Solution Overview
Problem
Existing hyperspectral imaging systems deployed in airborne and military applications are not compact and cannot be effectively deployed for scanning targets on existing platforms, lacking the necessary compactness and performance across the field and spectrum.
Innovation Solution
An airborne hyperspectral scanning system with a reflective telecentric relay, comprising fore-optics and a scanning mirror, which forms a telecentric pattern of radiation, allowing for compactness and aberrational correction, enabling cross-field scanning and maintaining telecentricity at the slit and spectrometer planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If existing hyperspectral imaging systems are deployed in airborne platforms, then spectral imaging capability is achieved, but the system size is large and cannot be effectively deployed for scanning targets
Solution Approach 1:
The patent implements a nested optical configuration where the relay optics are integrated within the spectrometer housing. The fore-optics, relay mirrors, and spectrometer components are arranged in a compact nested structure that reduces the overall system volume while maintaining full spectral imaging functionality. This allows the system to be deployed on existing airborne platforms where space is constrained.
Solution Approach 2:
The patent employs a folded optical path using multiple mirrors (fore-optics mirrors, relay mirrors) to redirect light through three-dimensional space. By folding the optical path and utilizing vertical space within the housing, the system achieves compactness in the horizontal dimension while maintaining the required optical path length for spectral imaging.
2Volume of moving object
If compact design is implemented, then system deployability is improved, but optical performance and spectral coverage may deteriorate
Solution Approach 1:
The patent employs local quality optimization by carefully designing the reflective surfaces of the fore-optics mirrors and relay mirrors with specific curvatures and orientations. Each mirror is optimized to correct optical aberrations in its local region while contributing to the overall compact folded path. This ensures that spectral and spatial resolution are maintained despite the compact design.
Solution Approach 2:
The patent achieves compactness while maintaining optical performance by changing key optical parameters including the curvatures, separations, and orientations of the mirror elements. The fore-optics and relay optics are designed with optimized parameter sets that enable a folded compact configuration while preserving diffraction-limited performance across the spectral range.
3Area of stationary object
If fore-optics is decentered to avoid vignetting, then field of view coverage is improved, but optical alignment complexity increases
Solution Approach 1:
The patent intentionally introduces asymmetry by decentering the fore-optics relative to the spectrometer entrance. This asymmetric configuration allows the optical axis of the fore-optics to be offset, enabling a wider field of view to be captured without vignetting. The asymmetric design is compensated by corresponding adjustments in the relay optics to maintain proper image formation.
Solution Approach 2:
The patent uses the relay optics as an intermediary system that bridges the decentered fore-optics and the spectrometer. The relay mirrors (including the scanning mirror) act as mediators that transfer the off-axis beam from the decentered fore-optics to the spectrometer entrance, managing the alignment complexity by providing intermediate optical transformations.
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 compactness while maintaining high performance, allowing for accurate spectral and spatial imaging across a wide field of view, with reduced distortions and improved spectral sampling, enabling effective target recognition.
Implementation Method 1
The fore-optics mirrors, situated in a form of a TMA, are configured so that electromagnetic radiation or light from a distant object is collected on the surface of the primary fore-optics mirror and directed toward the surface of the secondary fore-optics mirror. The secondary fore-optics mirror directs the light toward the surface of the tertiary fore-optics mirror, and the tertiary mirror forms an intermediate image
Data Source
AI summary
An airborne hyperspectral scanning system with a reflective telecentric relay including a system housing fore-optics, mounted in the housing, an imaging spectrometer mounted in the housing, the imaging spectrometer comprising a spectrometer slit, the spectrometer slit having an exit side and an entrance side, a focal plane array, a fold mirror, and at least three spectrometer mirrors, ordered sequentially, and in optical alignment with each other, and a reflective telecentric relay, mounted in the housing between the fore-optics and the imaging spectrometer, the reflective telecentric relay comprising a collimator module, a scanning mirror module, and an objective module, the objective module being situated to receive intermediate image from the fore-optics and reflect a collimated beam to the scanning mirror image between the collimator module and the objective module, wherein the objective module is situated to form a telecentric image at the entrance of the spectrometer slit.