SRS microscopy was discovered and reported earlier than cited

Dec. 1, 2009
This is in reference to the article “SRS microscopy maps distribution of lipids, drugs” by Barbara Goode (April 2009, p.24).

This is in reference to the article “SRS microscopy maps distribution of lipids, drugs” by Barbara Goode (April 2009, p. 24).

The paper gives the impression that SRS microscopy was first proposed and demonstrated by Freudiger et al.1 The article says that several groups reported similar works “after the publication of the said group’s work.” Further, it quotes Sunny Xie, “who lead the approach.”

I would like to point out that SRS microscopy was first successfully demonstrated by Dr. Volkmer’s group at the University of Stuttgart.2, 3 The first paper on SRS microscopy was presented by Dr. Volkmer at the the 8th European/French Israeli Symposium on Nonlinear and Quantum Optics (FRISNO-8), Ein Bokek, Feb. 20-25, 2005 ( All the attributes of SRS microscopy, such as linear dependency on number density, direct recording of the Raman spectra, absence of nonresonant background, among others, were clearly demonstrated in this paper (the talk presented by Dr. Volkmer is available on the website of the conference). Another article on SRS microscopy appeared in Optics Express, Vol. 17, 2009, in which the above presentation was cited.4 Further, a full-length article on SRS microscopy of He-La cells from the Volkmer group was received by New Journal of Physics on Nov. 26, 2008, and published in NJP, Vol. 11, 2009.

I would request you to kindly clarify this in a coming issue of your magazine and to make sure that proper credit is given to the original discovery.

P. Nandakumar,
Physics Group, Birla Institute of Technology and Science, Pilani - Goa Campus


  1. C.W. Freudinger et al., Science 322, p. 1857 (Dec. 19, 2008).
  2. P. Nandakumar, A. Kovalev, and A. Volkmer. Paper presented at the 17th Int’l. Conf. on Laser Spectroscopy (ICOLS 05), T54, Aviemore, June 19-24, 2005, and the 8th European/French Israeli Symp. on Nonlin. and Quant. Optics (FRISNO-8), Ein Bokek, Feb. 20-25, 2005 (
  3. P. Nandakumar, A. Kovalev, and A. Volkmer, New J. Phys. 11, 033026 (2009).
  4. Y. Ozeki et al., Optics Express 17, p. 3651 (March 2, 2009).
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