Scanning Fourier transform spectrometer in the visible range based on birefringent wedges

Area of Science:

• Optics and Photonics
• Spectroscopy
• Materials Science

Background:

• Fourier transform (FT) spectroscopy is a powerful technique for analyzing light-matter interactions.
• Traditional infrared FT spectrometers often use Michelson interferometers, which can be sensitive to environmental changes and require active stabilization.
• Measuring absorption spectra in the visible regime with high accuracy and stability presents unique challenges.

Purpose of the Study:

• To introduce a novel time-domain scanning Fourier transform (FT) spectrometer for visible absorption spectroscopy.
• To demonstrate a compact and stable interferometer design using birefringent wedges.
• To validate the performance and robustness of the new spectrometer against commercial instruments.

Main Methods:

• The spectrometer utilizes a common-mode passive interferometer based on birefringent wedges to generate delayed light replicas.
• This design inherently provides high path-length stability (approximately λ/300) without active feedback or beam tracking.
• Absorption spectra are measured in the visible light regime by analyzing the transmission of light through samples.

Main Results:

• The developed FT spectrometer successfully measured the transmission spectrum of a colored bandpass filter over a wide bandwidth (one octave).
• The instrument demonstrated excellent path-length stability and accuracy, crucial for reliable spectral measurements.
• Results obtained using the novel spectrometer were comparable to those from a commercial spectrophotometer, validating its performance.

Conclusions:

• The proposed birefringent wedge-based Fourier transform spectrometer offers a stable, accurate, and compact solution for visible absorption spectroscopy.
• This technique eliminates the need for complex active stabilization systems common in traditional FT spectrometers.
• The demonstrated performance suggests its potential for various applications in materials science, chemistry, and optical engineering.