Multi-Channel Imaging Spectrometer with Shared Optics

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Solution Overview

Problem

Conventional imaging spectrometers face challenges in achieving high signal-to-noise ratio over a broad spectral band without using multiple spectrometers, often resulting in large size, weight, and power requirements, especially when covering wide wavelength ranges or separate spectral regions.

Innovation Solution

A compact multi-band imaging spectrometer design utilizing a single entrance slit and shared optics with multiple dispersive elements, such as diffraction gratings or prisms, to achieve high signal-to-noise ratio and efficient spectral alignment, while maintaining a smaller field of view and reducing the need for multiple spectrometers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple spectrometers are used to cover wide wavelength ranges or separate spectral regions, then spectral coverage is improved, but size, weight and power requirements increase

Engineering Contradiction:
Improvespectral coverageVSAvoidsystem weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent combines multiple dispersive elements (multiple diffraction gratings or prisms) within a single spectrometer housing, allowing the system to cover wide wavelength ranges and separate spectral regions without requiring multiple separate spectrometer units. This merging approach maintains full spectral coverage capability while consolidating the system into one unit, thereby reducing overall size, weight, and power requirements compared to using multiple independent spectrometers.

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If multiple spectrometers are used to cover wide wavelength ranges or separate spectral regions, then spectral coverage is improved, but device complexity increases

Engineering Contradiction:
Improvespectral coverageVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple dispersive elements into a single integrated spectrometer system with shared optics and a common image sensor. This consolidation reduces device complexity by eliminating the need for multiple independent spectrometer units, while still achieving comprehensive spectral coverage through the coordinated operation of multiple dispersive elements within the unified system.

Inventive Principle:
Principle #5Merging (Combining)

3Device complexity

If a single dispersive element is used, then device complexity is reduced, but signal-to-noise ratio decreases

Engineering Contradiction:
Improvedispersive element configurationVSAvoidsignal-to-noise ratio
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies local quality by using multiple dispersive elements (multiple diffraction gratings or prisms) that are each optimized for specific wavelength ranges or spectral regions. This allows the system to maintain high signal-to-noise ratio performance across the entire spectral range by having specialized dispersive elements for different local spectral regions, rather than using a single general-purpose dispersive element that would compromise performance.

Inventive Principle:
Principle #3Local quality

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 provides a significantly higher signal-to-noise ratio compared to single-grating spectrometers, with improved spectral alignment and reduced size and weight, while maintaining comparable throughput to prism-based designs, and allows for better performance across a broader spectral range.

Implementation Method 1

The dispersive element may be a diffraction grating that provides linear dispersion

Methodology Applied
Scientific EffectDiffraction: Diffraction Grating

Implementation Method 2

The dispersive element may be a prism that provides non-linear dispersion

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

The output of the reflective triplet is incident upon a beamsplitter, which sends a collimated first reflective triplet output of a first wavelength to a first dispersive element, and a collimated second reflective triplet output of a second wavelength to a second dispersive element

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2877821B1High efficiency multi-channel spectrometer
Publication Date: 2021.08.18 RAYTHEON CO
  • EP2877821B1 patent drawingFigure 1A
  • EP2877821B1 patent drawingFigure 1B
  • EP2877821B1 patent drawingFigure 1C

AI summary

A multi-channel imaging spectrometer (100) and method of use thereof. One example of the multi-channel imaging spectrometer includes a single entrance slit (120), a double pass reflective triplet (110) and at least a pair of diffraction gratings (150, 160). The spectrometer is configured to receive and collimate an input beam from the entrance slit, to split the collimated beam into two spectral sub-bands using a beamsplitter (140), and to direct each sub-band to one of the pair of diffraction gratings. The diffraction gratings are each configured to disperse the received portion of the collimated beam into its constituent colors, and redirect the dispersed outputs through the reflective triplet to be imaged into an image sensor located at a focal plane (180) aligned with the entrance slit.