Remote Raman Sensing Using a Single-Grating Monolithic Spatial Heterodyne Raman Spectrometer: A Potential Tool for...

Area of Science:

• Spectroscopy
• Planetary Science Instrumentation

Background:

• Remote dispersive Raman spectrometers face challenges like large size, low light throughput, limited spectral range, and sensitivity to misalignment.
• Spatial heterodyne Raman spectrometers (SHRS) offer improvements, with one-grating SHRS (1g-SHRS) variants being more compact.

Purpose of the Study:

• To investigate a single-grating monolithic SHRS (1g-mSHRS) by integrating a 1g-SHRS with a monolithic setup.
• To assess the 1g-mSHRS as a candidate for planetary exploration instruments.

Main Methods:

• Developed a monolithic device integrating the beamsplitter, grating, and mirror.
• Characterized the 1g-mSHRS by measuring time-resolved remote Raman spectra of inorganic salts, organics, and minerals at 3 meters.
• Evaluated the instrument's spectral resolution, range, alignment sensitivity, and light throughput.

Main Results:

• The 1g-mSHRS achieved a compact footprint (35 × 35 × 25 mm, 80 g) with high spectral resolution (∼9 cm^-1) and a large spectral range (7327 cm^-1).
• Demonstrated decreased sensitivity to alignment and high light throughput.
• Successfully measured remote Raman spectra of various sample types at 3 meters.

Conclusions:

• The 1g-mSHRS is a promising candidate for planetary exploration due to its compact size, ease of alignment, and robust performance.
• Its features, including high spectral resolution, large spectral range, and low alignment sensitivity, address limitations of traditional dispersive Raman spectrometers for remote sensing.