Single-Delay Interferometer Stabilization for Compact Spectrographs

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Solution Overview

Problem

Conventional astronomical spectrographs are bulky and unstable under environmental stresses, such as vibration and thermal changes, making them unsuitable for compact, high-resolution applications like airborne platforms.

Innovation Solution

The use of a single-delay crossfading externally dispersed interferometer (EDI) technique to stabilize the output spectrum against wavelength drifts, allowing for compact and lightweight spectrographs with improved spectral resolution and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional astronomical spectrographs are used, then spectral resolution is achieved, but the system becomes bulky and unstable under environmental stresses

Engineering Contradiction:

Improvespectral resolutionVSAvoidstability under environmental stresses

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the conventional mechanical spectrograph system with an externally dispersed interferometer that uses optical interference patterns. Instead of relying on mechanical gratings and slits that are sensitive to environmental stresses, the system uses interferometric modulation with a delay line that can be stabilized through electronic control, thereby achieving high spectral resolution while improving reliability under vibration and thermal changes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters by using interferometric delay modulation instead of fixed optical paths. The delay line allows dynamic adjustment of the optical path difference, enabling the system to maintain spectral resolution while compensating for environmental disturbances through controlled parameter variation rather than rigid mechanical stability.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If conventional spectrographs are made compact, then portability is improved, but wavelength precision deteriorates due to environmental stresses

Engineering Contradiction:

Improvespectrograph sizeVSAvoidwavelength precision

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent replaces the bulky mechanical spectrograph components with a compact interferometric system. The externally dispersed interferometer uses a delay line and modulator instead of large gratings and focal planes, achieving wavelength precision through interferometric phase measurement rather than mechanical positioning, thus enabling compact design without sacrificing precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an interferometric modulator as an intermediary between the compact optical system and the detector. This modulator encodes spectral information through interference patterns, allowing the system to achieve high wavelength precision in a compact format by mediating the measurement process through interference rather than direct spatial dispersion.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If heavy concrete and steel structures are used to maintain rigidity, then optical stability is improved, but the system becomes too large for airborne platforms

Engineering Contradiction:

Improveoptical rigidityVSAvoidsystem volume

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

The patent replaces heavy mechanical rigidity structures with an interferometric system that achieves stability through optical interference and electronic stabilization. The delay line and modulator system maintains optical path stability through controlled interference patterns rather than relying on massive concrete and steel structures, enabling deployment on lightweight airborne platforms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a stable optical reference through interferometric copying of the spectral signal. The delay line produces a reference interference pattern that can be compared with the incoming signal, effectively copying and stabilizing the spectral information without requiring physical rigidity from heavy structures.

Inventive Principle:

Principle #26Copying

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 single-delay EDI technique enhances spectral resolution by 2× to 10× and stabilizes against wavelength drifts by up to 1000×, enabling high-resolution spectroscopy in compact, portable systems.

Implementation Method 1

externally dispersed interferometer (EDI) techniques

Methodology Applied

Scientific EffectInterference: Interference

Implementation Method 2

reverse the interferometer heterodyning

Methodology Applied

Scientific EffectHeterodyning: Heterodyne

Data Source

PatentUS12480815B2Spectrograph stabilization using a single-delay interferometer

Publication Date: 2025.11.25 LAWRENCE LIVERMORE NAT SECURITY LLC

AI summary

Methods, systems and devices are described that improve optical spectroscopic techniques and particularly those that involve externally dispersed interferometer (EDI) techniques that result in an output spectrum having improved stability characteristics. The output spectrum minimizes the unwanted shifts in wavelength when the spectrograph component of the EDI instrument is under stresses that would otherwise shift or distort the wavelength positions of the spectrum.