Digitally pressure-scanned fabry-perot interferometer for studying weak spectral lines

Area of Science:

• Spectroscopy
• Optical Physics
• Interferometry

Background:

• Fabry-Perot interferometers are sensitive optical instruments used for high-resolution spectral analysis.
• Accurate measurement of weak spectral signals requires highly linear and reproducible scanning techniques.
• Traditional scanning methods can suffer from non-linearity and noise, limiting their application for low-intensity phenomena.

Purpose of the Study:

• To develop and present a novel digital scanning system for Fabry-Perot interferometers.
• To achieve high linearity and reproducibility for recording weak spectral signals.
• To demonstrate the system's capability using depolarized Rayleigh scattering from hydrogen.

Main Methods:

• Digitally scanning the Fabry-Perot interferometer by incrementally adjusting the internal gas pressure.
• Implementing a system designed for high sensitivity, capable of detecting signals of a few counts per second.
• Utilizing discrete pressure steps for precise control over the interferometer's spectral free range.

Main Results:

• The developed scanning system exhibits high linearity, essential for accurate signal quantification.
• Repetitive scans demonstrate exceptional reproducibility, within 1/640 of the spectral free range.
• Successful recording of the depolarized Rayleigh line scattered by hydrogen at 2.5 amagat was achieved.

Conclusions:

• The digital scanning system offers a robust and precise method for analyzing weak spectral signals with Fabry-Perot interferometers.
• The high linearity and reproducibility make it suitable for demanding spectroscopic applications.
• The system's performance is validated by its application to measure the depolarized Rayleigh scattering of hydrogen.