Presentation
4 March 2019 Label-free imaging of tumorous tissue in the Raman fingerprint region with time-encoded (TICO) stimulated Raman scattering (Conference Presentation)
Author Affiliations +
Abstract
Raman microscopy has the potential of creating a molecular contrast in unstained tissue with high specificity at sub-cellular resolution. To overcome the low signal level in raster-scanned microscopy, commonly non-linear Raman techniques are employed. Imaging is usually performed in the CH-stretch region around 3000cm-1 with Raman contrast by spectral unmixing of the broadband lipid and protein Raman modes. Imaging in the fingerprint region around 1500cm-1 can yield higher information density due to the more specific molecular signatures. However, the problem is that in the fingerprint region the Raman signals are generally lower. We present Raman imaging in the fingerprint region of unstained tumorous tissue samples from human pharynx biopsies employing the time-encoded (TICO) technique. We chose pharynx tissue because this sample location can be accessed by future TICO-Raman endoscopes. In our fiber-based TICO-Raman system the stimulated Raman gain (SRG) signal is encoded in time by a Raman pump laser (1065nm, 600ps pulse length) synchronized to a wavelength-swept Fourier-Domain Mode-Locked (FDML) fiber laser. We sample the fingerprint region between 1300cm-1 – 1900 cm-1 with shot-noise limited sensitivity by employing a dual-balanced, digital and analogue balanced detector. The Stokes laser is a newly developed dispersion compensated FDML laser providing ultra-low noise and long coherence length at 400kHz sweep frequency and 100nm span around 1300nm. We investigate the possibility of applying higher instantaneous powers to increase the signal-to-noise ratio for imaging by lowering the relative shot-noise level suitable for detecting weak, narrowband Raman transitions in the fingerprint region.
Conference Presentation
© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hubertus Hakert, Matthias Eibl, Sebastian Karpf, Barbara Wollenberg, Ralph Pries, and Robert Huber "Label-free imaging of tumorous tissue in the Raman fingerprint region with time-encoded (TICO) stimulated Raman scattering (Conference Presentation)", Proc. SPIE 10882, Multiphoton Microscopy in the Biomedical Sciences XIX, 108821R (4 March 2019); https://doi.org/10.1117/12.2509851
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KEYWORDS
Raman spectroscopy

Tissues

Tumors

Raman scattering

Fiber lasers

Microscopy

Signal to noise ratio

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