Wide Field Spectral Imaging with Shifted Excitation Raman Difference Spectroscopy Using the Nod and Shuffle Technique
F. Korinth1, E. Schmälzlin2, C. Stiebing1, T. Urrutia2, G. Micheva2, C. Sandin3, A. Müller4, M. Maiwald4, B. Sumpf4, C. Krafft1, G. Tränkle4, M.M. Roth2 and J. Popp1,5
Published in:
Sensors, vol. 20, no. 23, art. 6723, doi:10.3390/s20236723 (2020).
Abstract:
Wide field Raman imaging using the integral field spectroscopy approach was used as a fast, one shot imaging method for the simultaneous collection of all spectra composing a Raman image. For the suppression of autofluorescence and background signals such as room light, shifted excitation Raman difference spectroscopy (SERDS) was applied to remove background artifacts in Raman spectra. To reduce acquisition times in wide field SERDS imaging, we adapted the nod and shuffle technique from astrophysics and implemented it into a wide field SERDS imaging setup. In our adapted version, the nod corresponds to the change in excitation wavelength, whereas the shuffle corresponds to the shifting of charges up and down on a Charge-Coupled Device (CCD) chip synchronous to the change in excitation wavelength. We coupled this improved wide field SERDS imaging setup to diode lasers with 784.4/785.5 and 457.7/458.9 nm excitation and applied it to samples such as paracetamol and aspirin tablets, polystyrene and polymethyl methacrylate beads, as well as pork meat using multiple accumulations with acquisition times in the range of 50 to 200 ms. The results tackle two main challenges of SERDS imaging: gradual photobleaching changes the autofluorescence background, and multiple readouts of CCD detector prolong the acquisition time.
1 Leibniz Institute of Photonic Technology (Leibniz IPHT), Member of Research Alliance "Health Technologies", Albert-Einstein-Straße 9, 07743 Jena, Germany
2 Leibniz Institute for Astrophysics Potsdam (AIP), Associated Member of Research Alliance "Health Technologies", An der Sternwarte 16, 14482 Potsdam, Germany
3 Sandin Advanced Visualization, Tylögränd 14, 12156 Johanneshov, Sweden
4 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Member of Research Alliance "Health Technologies", Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
5 Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
Keywords:
Raman spectroscopy; SERDS; wide field imaging; nod and shuffle; photobleaching; autofluorescence; integral field spectroscopy; background suppression; diode lasers
Copyright © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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