Spectrograph Anamorphic Beam Expansion for Resolution Throughput Trade-off
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Solution Overview
Problem
Conventional spectrographs face a trade-off between spectral resolution and throughput, often sacrificing throughput to achieve higher resolution, resulting in reduced data quality due to the limitations of aperture/slit combinations.
Innovation Solution
The use of anamorphic beam expanders and reformatters to reshape the input source image, allowing for a larger input aperture with minimal throughput loss, by independently manipulating the etendue of orthogonal axes, thereby increasing spectral resolution while maintaining high throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a narrow slit is used to achieve higher spectral resolution, then spectral resolution is improved, but throughput is reduced due to blocking of input light
Solution Approach 1:
The patent transforms the 2D aperture problem into a 3D solution by using a folded optical path with multiple reflections. The light traverses the dispersion direction multiple times through the slit, effectively increasing the interaction length without requiring a larger physical aperture. This dimensional transformation allows the system to achieve high spectral resolution while maintaining high throughput by utilizing the depth dimension of the optical path.
Solution Approach 2:
The patent introduces multiple reflective surfaces (mirrors) as intermediary elements that guide and redirect light through the slit multiple times. These intermediaries enable the light to interact with the dispersive element repeatedly, achieving high spectral resolution without requiring a narrow aperture that would block light. The reflective surfaces act as mediators that decouple the resolution requirement from the aperture size constraint.
2Loss of energy
If a large input aperture is used to maximize throughput, then throughput is improved, but spectral resolution is reduced due to larger image size along dispersion direction
Solution Approach 1:
The patent uses a folded optical path that extends the light traversal distance in the dispersion direction without increasing the physical footprint in the aperture plane. By folding the optical path through multiple reflections, the system achieves long effective path length (high resolution) while maintaining a large physical aperture (high throughput), effectively utilizing the depth dimension to resolve the contradiction.
Solution Approach 2:
The patent creates a dynamic light path where light repeatedly traverses the dispersion direction through multiple reflections. This dynamic traversal allows the same large aperture to produce a compressed image along the dispersion direction after multiple passes, achieving high spectral resolution while maintaining high throughput through the large aperture.
3Loss of energy
If multiple optical elements (mirrors, lenses) are added to reformat the beam, then spectral resolution and throughput are both improved, but device complexity increases
Solution Approach 1:
The patent segments the optical path into multiple discrete reflective sections, each handling a specific function (beam direction, focusing, dispersion). This segmentation allows for modular design and alignment, making the complex system more manageable. Each mirror or lens element is optimized for its specific function, and the segmented structure facilitates easier alignment and maintenance compared to a monolithic design.
Solution Approach 2:
The patent designs the optical elements to serve multiple functions: mirrors not only redirect light but also provide focusing and beam shaping; lenses serve both collimation and focusing roles. This multi-functionality reduces the total number of elements needed, thereby managing device complexity while achieving the dual goals of high spectral resolution and high throughput.
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 approach enables improved spectral resolution with high throughput efficiency, allowing for a sharper view of spectral features without the need for significant light loss, thus enhancing data quality.
Implementation Method 1
configured to expand a light beam received from a source along a second axis, orthogonal to a dispersion axis, by means of refraction or reflection
Implementation Method 2
configured to expand a light beam received from a source along a second axis, orthogonal to a dispersion axis, by means of refraction or reflection
Implementation Method 3
a dispersing element which bends the light beam through different angles depending on wavelength
Data Source
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AI summary
A spectrograph including light beam reformatting element(s), beam expander(s), dispersive element(s) and light receiving element(s). The light beam reformatting element(s) reformat a received light beam into a reformatted light beam having a first dimension along a first axis that is larger than a dimension of the received light beam along the first axis and a second dimension along a second axis substantially orthogonal to the first axis that is smaller than a dimension of the received light beam along the second axis. The beam expander(s) anamorphically expand the reformatted light beam along the second axis into an expanded light beam. The dispersive element(s) disperse the expanded light beam along the second axis, resulting in a dispersed light beam. The light receiving element(s) receive the dispersed light beam. The light receiving element(s) may include one or more detectors to measure spectral intensity of the dispersed light beam.