Parasitic diffuse reflection in a Fourier transform spectrometer yielding subharmonic ghosts and line-shape...

Area of Science:

• Spectroscopy
• Optical Engineering

Background:

• High-resolution Fourier transform spectrometers (FTS) are susceptible to spectral artifacts.
• Parasitic diffuse reflections within the FTS optical path can lead to ghost signals.

Purpose of the Study:

• To investigate the origin and characteristics of subharmonic ghosts in cube-corner FTS.
• To understand the impact of diffuse reflections on spectral measurements.

Main Methods:

• Utilized a high-resolution Fourier transform spectrometer in a cube-corner configuration.
• Analyzed spectral data to identify and characterize subharmonic ghost signals.
• Investigated the role of parasitic diffuse reflections on interferometer mirrors.

Main Results:

• Observed subharmonic ghosts in the FTS spectra, attributed to diffuse reflections.
• Identified that these reflections cause beams to travel different optical paths, altering optomechanical gain.
• Demonstrated that both reference laser and measurement channels are affected, leading to sampling jitter and additive subharmonics.

Conclusions:

• Diffuse reflections are a primary source of subharmonic ghosts in cube-corner FTS.
• These ghosts compromise spectral accuracy, affecting instrument line shape and radiometric calibration.
• Mitigation strategies for diffuse reflections are crucial for reliable FTS operation.