ms-Time Resolution Raman Spectroscopy Using sCMOS cameras

Raman spectroscopy is a powerful tool to interrogate biological and material systems, as Raman spectra provide a chemical specificity that can be used to monitor chemical reactions, identify molecular structures, and measure the distribution of chemical species throughout a sample. The development of novel Raman methods has, in part, been enabled through development in detector technologies. Here we discuss the application of a scientific Complementary Metal Oxide Semiconductor (sCMOS) camera as a detection solution for Raman spectroscopy. Whereas CCD cameras have traditionally found popularity in experimental Raman set ups, the readout architecture of sCMOS cameras provides an attractive detector platform for fast Raman spectroscopy and can outperform CCDs under certain experimental conditions. We highlight the advantages of sCMOS and CCD detectors for Raman spectroscopy, and spectroscopy more generally, using a dual output spectrometer to ensure an equivalent optical set up for both cameras.

Image Readout Architecture of Scientific Cameras

Experimental Detection Set-ups

High-Fidelity Spatially Resolved Spectra with sCMOS

The individual pixel readout architecture of sCMOS cameras reduces artifacts (e.x. smearing, blooming), lending it to high fidelity imaging experiments. This is demonstrated by Raman spectral images of a biphasic system and mixing in a microfluidic system.

Exploring experimental conditions using Polystyrene (PS) beads

Spectra to left after normalization to integrated peak area.

CARS spectra of PS (1064 pump, reduced power) recorded with a 5 ms exposure time. EMCCD excels at reduced photon fluences.

Future Outlook for sCMOS as a Spectroscopy Camera

The performance of sCMOS cameras for spectroscopy applications has been explored and contrasted where appropriate with CCD cameras. In a weak signal regime CCD technology can hold an advantage. At moderate photon fluxes, the relatively small performance difference in conjunction with additional technological advantages are a clear indicator sCMOS cameras can readily be considered for spectroscopy applications. Moving towards high photon fluxes, sCMOS cameras can already outperform standard CCD detectors and hold a significant advantage for fast-spectroscopy applications.

References and Acknowledgements

W.J.N. Klement, P. Leproux, W.R. Browne, H. Kano, CMOS and CCD detection in Raman spectroscopy: a comparison using spontaneous and multiplex coherent anti-Stokes Raman scattering (CARS), ChemRxiv, 2024, DOI: 10.26434/chemrxiv-2024-vqjlz

W.J.N. Klement, E. Savino, W.R. Browne, E. Verpoorte, In-line Raman imaging of mixing by herringbone grooves in microfluidic channels, Lab Chip, 2024, 24, 3498-3507, DOI: 10.1039/D4LC00115J

W.J.N Klement, S. Verpoorte, W.R. Browne, Seeing Mixing in Microfluidic Channels with Line Focused Raman Imaging, Andor Learning Center, 2024

The authors would like to thank Phillipe Leproux and Buillaume Huss (Leukos) for their assistance with data collection. This work was funded, in part, by the Ubbo Emmius fund of the University of Groningen.