Spectral Encoder Double-Pass Offner Spectrograph
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Solution Overview
Problem
Current spectral imaging technologies face challenges in achieving high image quality and signal-to-noise ratio due to image aberrations and inefficient light collection, particularly in two-dimensional imaging applications, where the dispersed image is not placed near the center of curvature along the dispersion axis and the use of multiple gratings and optical surfaces is required.
Innovation Solution
The implementation of a double-pass spectrograph with a vertical Offner configuration, where the dispersed image is placed near the center of curvature along the dispersion axis, using a single grating and additional curved optical elements, and omitting the slit to maximize light collection and reduce image aberrations, allowing for high-quality two-dimensional imaging with improved signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the dispersed image is placed away from the center of curvature along the dispersion axis, then the device complexity is reduced, but image quality deteriorates due to increased image aberrations
Solution Approach 1:
The patent employs a curved grating with a specific radius of curvature to disperse light while maintaining image quality. The curved geometry of the grating allows the dispersed image to be formed at a distance from the center of curvature while compensating for aberrations through the curved surface design, thus resolving the contradiction between device complexity and image quality.
2Manufacturing precision
If multiple gratings and curved optical surfaces are used, then image quality is improved, but device complexity increases
Solution Approach 1:
The patent combines the functions of multiple optical elements into a single curved grating system. The curved grating simultaneously performs dispersion and focusing functions that would otherwise require separate gratings and curved mirrors, reducing device complexity while maintaining image quality through the integrated optical design.
3Measurement precision
If a slit is included in the optical system, then spectral resolution is improved, but light collection efficiency deteriorates
Solution Approach 1:
The patent removes the traditional slit element from the optical system and replaces it with a computational approach using curved grating geometry and detector pixel mapping. This extraction of the physical slit eliminates light loss while maintaining spectral resolution through the mathematical relationship between the curved grating dispersion and detector pixel positions.
4Manufacturing precision
If the dispersed image is placed near the center of curvature, then image aberrations are reduced, but device complexity increases due to precise positioning requirements
Solution Approach 1:
The patent optimizes the radius of curvature parameter of the grating to a specific value that allows the dispersed image to be formed at an optimal distance from the center of curvature. By carefully selecting this geometric parameter, the system achieves minimal aberrations without requiring extremely precise positioning tolerances, thus balancing image quality with device 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 enhances image quality and signal-to-noise ratio by minimizing image aberrations and increasing light collection, making it suitable for applications in the infrared range and enabling the use of smaller detectors, thus improving spectral imaging performance.
Implementation Method 1
an imaging spectrograph that defines a first optical path that produces from the input radiation field a spectrally dispersed image comprising multiple spectral components displaced along a dispersion direction
Implementation Method 2
additional curved optical elements, and omitting the slit to maximize light collection
Implementation Method 3
an imaging spectrograph that defines a first optical path that produces from the input radiation field a spectrally dispersed image
Data Source
AI summary
A spectral encoder for producing spectrally selected images of a radiation field containing multiple spectral components. An imaging spectrograph defines a first optical path that produces from the input radiation field a spectrally dispersed image comprising multiple spectral components displaced along a dispersion direction. Spectral pass bands are encoded on the dispersed image by a programmable spatial light modulator using one or more spatial masks. The imaging spectrograph further defines a second optical path that reverses the spectral dispersion of the first path and produces a spectrally-encoded polychromatic output image containing only those spectral components encoded by the spatial mask. The first and second optical paths share a common dispersing element. A detector records at least one spatial region of the spectrally encoded output image.