Development of Digital Sampling for Spaceborne Fourier Transform Spectrometers Using Dual Reference Channel.

Area of Science:

• Spaceborne instrumentation
• Optical spectroscopy
• Digital signal processing

Background:

• Spaceborne Fourier Transform Spectrometers (FTSs) require robust digital sampling pipelines for harsh environments.
• Existing methods often rely on dedicated hardware for interferometer control and sampling.
• Environmental factors like vibrations and temperature fluctuations impact FTS performance.

Purpose of the Study:

• To develop and evaluate an original digital sampling pipeline for spaceborne FTSs.
• To improve spectrometer robustness without dedicated electronic hardware.
• To compare different metrology laser channel configurations for interferogram sampling.

Main Methods:

• Implementation of a constant time step sampling using a standard Analogue to Digital Converter (ADC).
• Development of a MATLAB-based simulator to emulate FTS operation, including vibrations and detector noise.
• Evaluation of improved arccosine methods and novel techniques using two metrology laser channels (same and different wavelengths).

Main Results:

• The optimal combination of two same-wavelength reference channels with a π/2 phase shift consistently outperformed other configurations.
• This optimal configuration yielded lower average spectral errors and more stable performance across various disturbances and noise levels.
• Dual-wavelength strategies showed reduced accuracy but offered flexibility when fixed phase shifts were not feasible.

Conclusions:

• The proposed digital sampling pipeline enhances FTS robustness for spaceborne applications.
• Optimized dual-reference channel configurations, particularly same-wavelength with phase shift, are highly promising.
• Further development and testing of an instrument breadboard are recommended.