Instrumental phase-based method for Fourier transform spectrometer measurements processing.

Area of Science:

• Spectroscopy
• Optical Engineering
• Planetary Science

Background:

• Space-borne Fourier transform spectrometers (FTSs) require accurate phase correction for reliable data.
• Environmental factors like temperature fluctuations and mechanical disturbances degrade FTS accuracy, especially with low signal-to-noise ratios (SNR).

Purpose of the Study:

• To develop and validate a robust phase correction method for FTS instruments operating under challenging environmental conditions, specifically temperature variations and mechanical disturbances.
• To improve the accuracy and reliability of spectral data for space-borne applications.

Main Methods:

• Implemented a phase correction method based on identifying an instrumental phase dependent on interferometer temperature.
• Utilized a least-squares approach to extract a linear phase component from a narrow spectral region immune to disturbances.
• Validated the method using ground and in-flight measurements from the Planetary Fourier Spectrometer (PFS) on the Mars Express mission.

Main Results:

• The developed method effectively corrects phase errors caused by instrumental effects and environmental disturbances.
• Parameterizing the instrumental phase with interferometer temperature enhances the determination of the linear phase component.
• The procedure demonstrated robustness, enabling effective spectra averaging and calibration, even with significant beamsplitter emission.

Conclusions:

• The proposed phase correction technique is vital for enhancing the accuracy of space-borne FTS data.
• The method's applicability extends to other FTS instruments with suitable spectral regions of high SNR and manageable beamsplitter emission.
• Successful application to the Mars IR Mapper and PFS instruments highlights its value for planetary exploration.