Journal of the European Optical Society - Rapid publications, Vol 10 (2015)
Optimized signal-to-noise ratio with shot noise limited detection in Stimulated Raman Scattering microscopy
Abstract
We describe our set-up for Stimulated Raman Scattering (SRS) microscopy with shot noise limited detection for a broad window of biologically relevant laser powers. This set-up is used to demonstrate that the highest signal-to-noise ratio (SNR) in SRS with shot noise limited detection is achieved with a time-averaged laser power ratio of 1:2 of the unmodulated and modulated beam. In SRS, two different coloured laser beams are incident on a sample. If the energy difference between them matches a molecular vibration of a molecule, energy can be transferred from one beam to the other. By applying amplitude modulation to one of the beams, the modulation transfer to the other beam can be measured. The efficiency of this process is a direct measure for the number of molecules of interest in the focal volume. Combined with laser scanning microscopy, this technique allows for fast and sensitive imaging with sub-micrometre resolution. Recent technological advances have resulted in an improvement of the sensitivity of SRS applications, but few show shot noise limited detection.
The dominant noise source in this SRS microscope is the shot noise of the unmodulated, detected beam. Under the assumption that photodamage is linear with the total laser power, the optimal SNR shifts away from equal beam powers, where the most signal is generated, to a 1:2 power ratio. Under these conditions the SNR is maximized and the total laser power that could induce photodamage is minimized. Compared to using a 1:1 laser power ratio, we show improved image quality and a signal-to-noise ratio improvement of 8 % in polystyrene beads and C. Elegans worms. Including a non-linear damage mechanism in the analysis, we find that the optimal power ratio converges to a 1:1 ratio with increasing order of the non-linear damage mechanism.
© The Authors. All rights reserved. [DOI: 10.2971/jeos.2015.15022]
Citation Details
Cite this article
References
C. W. Freudiger, W. Min, B. G. Saar, S. Lu, G. R. Holtom, C. W. He, J. C. Tsai, J. X. Kang, and X. S. Xie, â€Label-Free Biomedical Imaging with High Sensitivity by Stimulated Raman Scattering Microscopy,†Science 322, 1857–1861 (2008).
P. Nandakumar, A. Kovalev, and A. Volkmer, â€Vibrational imaging based on stimulated Raman scattering microscopy,†New J. Phys. 11, 9 (2009).
T. Meyer, M. Schmitt, B. Dietzek, and J. Popp, â€Accumulating advantages, reducing limitations: Multimodal nonlinear imaging in biomedical sciences – the synergy of multiple contrast mechanisms,†J. Biophotonics 6, 887–904 (2013).
Y. Ozeki, Y. Kitagawa, K. Sumimura, N. Nishizawa, W. Umemura, S. Kajiyama, K. Fukui, and K. Itoh, â€Stimulated Raman scattering microscope with shot noise limited sensitivity using subharmonically synchronized laser pulses,†Opt. Express 18, 13708–13719 (2010).
K. Nose, Y. Ozeki, T. Kishi, K. Sumimura, N. Nishizawa, K. Fukui, Y. Kanematsu, and K. Itoh, â€Sensitivity enhancement of fiber-laserbased stimulated Raman scattering microscopy by collinear balanced detection technique,†Opt. Express 20, 13958–13965 (2012).
C. W. Freudiger, W. L. Yang, G. R. Holtom, N. Peyghambarian, X. S. Xie, and K. Q. Kieu, â€Stimulated Raman scattering microscopy with a robust fibre laser source,†Nat. Photonics 8, 153–159 (2014).
B. G. Saar, C. W. Freudiger, J. Reichman, C. M. Stanley, G. R. Holtom, and X. S. Xie, â€Video-Rate Molecular Imaging in Vivo with Stimulated Raman Scattering,†Science 330, 1368–1370 (2010).
Y. Ozeki, W. Umemura, Y. Otsuka, S. Satoh, H. Hashimoto, K. Sumimura, N. Nishizawa, K. Fukui, and K. Itoh, â€High-speed molecular spectral imaging of tissue with stimulated Raman scattering,†Nat. Photonics 6, 844–850 (2012).
C. W. Freudiger, R. Pfannl, D. A. Orringer, B. G. Saar, M. B. Ji, Q. Zeng, L. Ottoboni, W. Ying, C. Waeber, J. R. Sims, P. L. De Jager, O. Sagher, M. A. Philbert, X. Y. Xu, S. Kesari, X. S. Xie, and G. S. Young, â€Multicolored stain-free histopathology with coherent Raman imaging,†Lab. Invest. 92, 1492–1502 (2012).
M. N. Slipchenko, R. A. Oglesbee, D. L. Zhang, W. Wu, and J. X. Cheng, â€Heterodyne detected nonlinear optical imaging in a lock-in free manner,†J. Biophotonics 5, 801–807 (2012).
S. Hong, T. Chen, Y. Zhu, A. Li, Y. Huang, and X. Chen, â€Live-Cell Stimulated Raman Scattering Imaging of Alkyne-Tagged Biomolecules,†Angew. Chem. Int. Edit. 53, 5827–5831 (2014).
L. Wei, F. Hu, Y. Shen, Z. Chen, Y. Yu, C.-C. Lin, M. C. Wang, and W. Min, â€Live-cell imaging of alkyne-tagged small biomolecules by stimulated Raman scattering,†Nat. Methods 11, 410–2 (2014).
W. Rock, M. Bonn, and S. H. Parekh, â€Near shot-noise limited hyperspectral stimulated Raman scattering spectroscopy using low energy lasers and a fast CMOS array,†Opt. Express 21, 15113–15120 (2013).
X. Zhang, M. B. J. Roeffaers, S. Basu, J. R. Daniele, D. Fu, C. W. Freudiger, G. R. Holtom, and X. S. Xie, â€Label-Free Live-Cell Imaging of Nucleic Acids Using Stimulated Raman Scattering Microscopy,†Chemphyschem 13, 1054–1059 (2012).
Y. Ozeki, F. Dake, S. Kajiyama, K. Fukui, and K. Itoh, â€Analysis and experimental assessment of the sensitivity of stimulated Raman scattering microscopy,†Opt. Express 17, 3651–3658 (2009).
Y. Fu, H. F. Wang, R. Y. Shi, and J. X. Cheng, â€Characterization of photodamage in coherent anti-Stokes Raman scattering microscopy,†Opt. Express 14, 3942–3951 (2006).
C. W. Freudiger, M. B. J. Roeffaers, X. Zhang, B. G. Saar, W. Min, and X. S. Xie, â€Optical Heterodyne-Detected Raman-Induced Kerr Effect (OHD-RIKE) Microscopy,†J. Phys. Chem. B 115, 5574–5581 (2011).
E. O. Potma, C. L. Evans, and X. S. Xie, â€Heterodyne coherent anti- Stokes Raman scattering (CARS) imaging,†Opt. Lett. 31, 241–243 (2006).
K. I. Popov, A. F. Pegoraro, A. Stolow, and L. Ramunno, â€Image formation in CARS and SRS: effect of an inhomogeneous nonresonant background medium,†Opt. Lett. 37, 473–475 (2012).
T. Hellerer, C. Axäng, C. Brackmann, P. Hillertz, M. Pilon, and A. Enejder, â€Monitoring of lipid storage in Caenorhabditis elegans using coherent anti-Stokes Raman scattering (CARS) microscopy,†Proc. Natl. Acad. Sci. U S A 104, 14658–14663 (2007).
A. Hopt and E. Neher, â€Highly nonlinear photodamage in twophoton fluorescence microscopy,†Biophys. J. 80, 2029–2036 (2001).
K. König, T. W. Becker, P. Fischer, I. Riemann, and K. J. Halbhuber, â€Pulse-length dependence of cellular response to intense nearinfrared laser pulses in multiphoton microscopes,†Opt. Lett. 24, 113–115 (1999).