The aim of the Raman research stream is to develop high-speed Raman imaging and combined Raman and fluorescence imaging and explore potential applications in the medical field and beyond. In the visible region of the spectrum Raman signals are often swamped by fluorescence. We use time correlated single photon counting techniques to measure Raman signals before fluorescence signals.

Key people:

High-speed Raman

An imager with a custom spectrometer has demonstrated millisecond acquisition times for Raman spectra and hundreds of kiloHz Raman count rates representing some of the best commercial or academic results to date. Relevant publication: Finlayson, N., Usai, A., Brown, G. E., McEwan, H., Erdogan, A. T., Campbell, C. J., & Henderson, R. K. (2021). Time-correlated single photon Raman spectroscopy at megahertz repetition rates. Optics Letters, 46(17), 4104-4107. https://doi.org/10.1364/OL.434418

Figure 1 Diamond Raman spectra obtained using 1, 2, 5, and 10 ms acquisition times

Other technologies under development include:

  • A Gen II spectrometer, following preliminary results for high-speed time-correlated single photon counting (TCSPC) Raman imaging. The new spectrometer has an order of magnitude greater light gathering efficiency
  • A motorised Raman imaging stage with low frame rate
  • A confocal Raman imager

Raman and fluorescence

The high-speed Raman imager will be integrated into the inverted Kronoscan system to generate combined Raman and fluorescence images. Although Raman signals are generally considerably weaker than fluorescence the Raman spectra carry more specific information about the molecular constituents. We aim to demonstrate that bimodal time-resolved Raman and fluorescence imaging provides highly complementary spectroscopic information.

Potential applications

Collaborations with other researchers at the University of Edinburgh School of Chemistry are exploring Raman signals from liver tissue samples.

Bone specialists in the University of Edinburgh School of Medicine will provide bone samples to look at how Raman and fluorescence imaging could help to identify and target infections post-operation.

There are many applications outside of the life sciences, for example in materials sciences. Raman spectroscopy is of considerable importance in improving battery and fuel cell performance, providing information about structural changes occurring in battery cathode and anode materials. Other applications include mineralogy. As the technology develops, these areas will also be explored.