Handheld Raman Spectroscopy - For Art and Cultural Heritage Analysis

Importance of the Topic

Non‐invasive, in situ molecular analysis of artworks and cultural heritage objects plays a pivotal role in conservation science. Complex materials such as pigments, binders, waxes and fillers require careful examination without sampling or relocation. Handheld spectroscopic tools deliver rapid, contact‐free characterization, minimizing risk to priceless artifacts and enabling on‐site decision making.

Objectives and Overview of the Study

This study presents the BRAVO handheld Raman spectrometer, designed specifically for art and heritage analysis. The instrument aims to combine benchtop performance with portability, overcome fluorescence interference, extend spectral coverage from 170 to 3200 cm⁻¹, and maintain high wavenumber accuracy. Key goals include validating fluorescence mitigation by shifted excitation, demonstrating sensitivity at low laser power, and highlighting remote operation and data evaluation workflows.

Methodology and Instrumentation

The BRAVO system employs DuoLaser™ excitation at two visible wavelengths to optimize Raman scattering efficiency. A patented Sequentially Shifted Excitation (SSE™) technique suppresses fluorescence without resorting to near‐infrared excitation. High quality optics and detection electronics deliver low noise performance while keeping laser output power below 100 mW, reducing sample heating. The system supports remote control via WiFi or Ethernet, enabling tripod‐based measurements and precise parameter adjustment through a computer interface.

Instrumentation Used

• BRAVO handheld Raman spectrometer (Bruker Optics)
• DuoLaser™ visible excitation covering 170–3200 cm⁻¹
• Patented SSE™ fluorescence mitigation module
• High-resolution optical bench with typical wavenumber accuracy of ±1 cm⁻¹
• Low‐noise detector optimized for visible Raman signals
• Remote control software via OPUS suite
• Tripod mount for stable, hands‐free operation

Main Results and Discussion

Tests on standard and real‐world samples confirm that SSE™ effectively removes overwhelming fluorescence backgrounds, producing spectra comparable to benchtop FT-Raman at 1064 nm. Kaolin measurements illustrate clear retrieval of Raman bands in the fingerprint region when using SSE™, with minimal residual baseline and no compromise in sensitivity. The instrument maintains excellent spectral resolution and accuracy, crucial for reliable library matching. Remote operation showed seamless data collection on mounted samples, with built-in pigment and binder databases providing rapid material identification.

Benefits and Practical Applications

The BRAVO handheld Raman offers several tangible advantages for cultural heritage practitioners:

• Non‐destructive, contact‐free analysis reducing risk to samples
• Wide spectral range for comprehensive organic and inorganic compound detection
• Low laser power minimizes sample heating and alteration
• Fluorescence suppression without loss of sensitivity
• Rapid on‐site material identification through integrated spectral libraries
• Remote controlled measurements facilitating stable, tripod‐mounted operation

Future Trends and Opportunities

Emerging developments may include deeper integration of machine learning for automated spectral interpretation, expansion of reference databases to cover niche conservation materials, and coupling handheld Raman with complementary modalities such as portable XRF or imaging systems. Advances in detector technology and miniaturized optics will further enhance sensitivity and spectral coverage, reinforcing the role of portable Raman in field and museum environments.

Conclusion

The BRAVO handheld Raman spectrometer achieves benchtop‐level sensitivity and accuracy in a portable format, delivering robust fluorescence mitigation and extensive spectral range. This combination empowers conservators, museum scientists, and analysts to perform precise, non‐invasive material characterization on cultural heritage objects, directly supporting preservation and research initiatives.

Reference

• Conti M et al., Analyst 141, 4599 (2016)
• Vagnini M et al., Spectrochim Acta A 176, 174 (2017)
• Bruker Product Note T29, Efficient mitigation of fluorescence in Raman spectroscopy using SSE™ (2015)
• Bruker Product Note R34, Advanced Data Acquisition and Evaluation in Handheld Raman Spectroscopy (2016)