Imaging Spectrometer with Reflective Grating for Non-Unit Magnification
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Solution Overview
Problem
Conventional imaging spectrometers with reflective gratings are limited to unit magnification or magnification ratios close to one, making it difficult to design compact, cost-effective instruments with high performance, as altering magnification introduces strong aberrations and compromises image quality.
Innovation Solution
The design of an imaging spectrometer using first to fourth curved reflective portions, alternatingly concave and convex, with at least one having a reflective grating structure, allows for magnification values different from one, achieved through a compact and flexible configuration with a monolithic optical element, enabling both smaller and larger magnifications without compromising image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional imaging spectrometer designs with reflective gratings are used, then the instrument structure is simple and easy to manufacture, but the magnification is limited to unit magnification or values close to one, preventing compact design
Solution Approach 1:
The patent introduces asymmetric optical paths with different numbers of reflections (e.g., 2-1-2-1 pattern) to achieve non-unit magnification. This breaks the symmetry of conventional designs while maintaining manufacturing feasibility through standard reflective gratings and simple optical components.
Solution Approach 2:
The patent utilizes multiple reflection dimensions and spatial arrangements to achieve compact folding of optical paths. By arranging reflections in sequences like 2-1-2-1 across different spatial dimensions, the instrument achieves reduced length without sacrificing magnification flexibility.
2Adaptability or versatility
If the magnification value is changed in conventional designs, then different magnification ratios can be achieved, but strong aberrations are introduced and image quality deteriorates
Solution Approach 1:
The patent employs curved reflective surfaces and optimized reflection geometries to correct aberrations introduced by non-unit magnification. The curved paths and carefully designed reflection angles compensate for optical distortions, maintaining image quality across various magnification values.
Solution Approach 2:
The patent systematically optimizes multiple parameters including reflection angles, path lengths, and component positions to minimize aberrations. By adjusting these parameters in the asymmetric optical paths, the design achieves both magnification flexibility and high image quality without introducing strong aberrations.
3Adaptability or versatility
If freeform gratings are used to achieve non-unit magnification, then magnification flexibility is improved, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent divides the optical function into multiple discrete reflection segments rather than using a single complex freeform grating. Each segment performs a specific function (collimation, dispersion, focusing) and can be manufactured separately using standard components, reducing overall complexity.
Solution Approach 2:
The patent makes standard reflective gratings perform multiple functions through clever geometric arrangement. The same grating type serves for dispersion while the asymmetric optical path configuration achieves magnification control, eliminating the need for specialized freeform gratings and reducing manufacturing complexity.
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 configuration enables the creation of compact, lightweight optical instruments with flexible magnification options, improving image quality and reducing aberrations, while using conventional reflective gratings instead of freeform gratings, which are difficult to manufacture and expensive.
Implementation Method 1
The output beam of light at the focal plane is dispersed in accordance with a spectral composition of the beam of light received from the slit
Implementation Method 2
the beam of light, in its passage from the slit to the focal plane, sequentially strikes the first to fourth curved reflective portions and is reflected by the first to fourth curved reflective portions
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
This application relates to an imaging spectrometer (200) for receiving a beam of light from a slit (20) and outputting the beam of light to a focal plane (30). The output beam of light at the focal plane is dispersed in accordance with a spectral composition of the beam of light received from the slit. The imaging spectrometer comprises first to fourth curved reflective portions (210, 220, 230, 240). The first to fourth curved reflective portions are arranged so that the beam of light, in its passage from the slit to the focal plane, sequentially strikes the first to fourth curved reflective portions and is reflected by the first to fourth curved reflective portions. Further, the first to fourth curved reflective portions are alternatingly concave or convex, respectively, along the passage of the beam of light. At least one of the first to fourth curved reflective portions (219, 230) has a reflective grating structure. The application further relates to a method of manufacturing such imaging spectrometer.