Fabry-Perot Spatial Fourier Spectrometer Without Moving OPD
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Solution Overview
Problem
Conventional Fourier transform spectrometers using Michelson interferometers require time-varying optical path differences for wavelength recovery, which can be complex and inefficient, while spatial FTSs using gradient OPDs face challenges in detector uniformity and non-uniformity corrections.
Innovation Solution
A Fourier transform spectrometer employing a Fabry-Perot interferometer with spatially varying gaps between optical surfaces to create interference patterns, allowing for direct spectral content determination without time-varying optical path differences, using a detector array to capture and process these patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Michelson interferometer is used with time-varying optical path differences, then wavelength recovery is achieved, but device complexity and operational complexity increase
Solution Approach 1:
The patent replaces the mechanical Michelson interferometer system with a stationary Fabry-Perot interferometer system. Instead of using moving mirrors to create time-varying optical path differences, the invention uses a stationary resonant cavity with spatially varying gap to create spatial interference patterns that are captured by a detector array, thereby eliminating mechanical complexity while maintaining spectral measurement capability
Solution Approach 2:
The patent transitions from time-domain measurement (Michelson interferometer with varying OPD over time) to spatial-domain measurement (Fabry-Perot interferometer with spatially varying gap). The interference pattern is encoded in space rather than time, allowing simultaneous spectral information capture across multiple wavelengths using a detector array positioned in the spatial domain
2Productivity
If spatial FTS with gradient OPD is used, then spectral content is encoded in spatial pattern, but detector uniformity and non-uniformity corrections become complex
Solution Approach 1:
The patent employs a Fabry-Perot interferometer with spatially varying gap characteristics that create localized interference patterns. The gap between optical surfaces is deliberately made non-uniform (e.g., linear or quadratic variation) to encode spectral information in a controlled manner, allowing each spatial location to represent specific wavelength information without requiring complex uniformity corrections across the detector array
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
Enables efficient spectral content analysis with simplified setup and reduced complexity, achieving accurate spectral resolution without the need for time-varying optical path differences or complex detector uniformity corrections.
Implementation Method 1
a Fabry-Perot interferometer to create an interference pattern using input light
Implementation Method 2
first and second optical surfaces that are partially transmissive and partially reflective to the light
Implementation Method 3
the first and second optical surfaces defining a resonant cavity therebetween
Data Source
AI summary
A spatial Fourier transform spectrometer is disclosed. The Fourier transform spectrometer includes a Fabry-Perot interferometer with first and second optical surfaces. The gap between the first and second optical surfaces spatially varies in a direction that is orthogonal to the optical axis of the Fourier transform spectrometer. The Fabry-Perot interferometer creates an interference pattern from input light. An image of the interference pattern is captured by a detector, which is communicatively coupled to a processor. The processor is configured to process the interference pattern image to determine information about the spectral content of the input light.