OSA's Digital Library

Applied Spectroscopy

Applied Spectroscopy

| PUBLISHED BY SAS — AVAILABLE FROM SAS AND OSA

  • Vol. 57, Iss. 11 — Nov. 1, 2003
  • pp: 1324–1332

Confocal Raman Microspectrometry: A Vectorial Electromagnetic Treatment of the Light Focused and Collected Through a Planar Interface and Its Application to the Study of a Thin Coating

C. Sourisseau and P. Maraval

Applied Spectroscopy, Vol. 57, Issue 11, pp. 1324-1332 (2003)


View Full Text Article

Acrobat PDF (422 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations
  • Export Citation/Save Click for help

Abstract

In-depth confocal Raman microspectrometry (CRM) studies through a planar interface between materials of mismatched refraction indices are known to be affected by a decrease of both the collected Raman intensity and the axial resolution as a function of the penetration depth. Following a previous model, which takes the refraction, diffraction, and spherical aberration effects into account when focusing a Gaussian incident laser beam with a high numerical aperture objective lens, a complete vectorial treatment of these phenomena is considered. It is demonstrated that off-axis refraction effects cannot be neglected and that the dimension of the confocal pinhole aperture plays a crucial role on the effective focal plane position and on the collection efficiency. We thus propose a more rigourous and complete approach to the problem, and we find a very good agreement between experimental and theoretical Raman intensity variations for a thick polyethylene sample as a function of the penetration depth. As compared with calculations where only refraction was considered, we confirm that the lengthening of the focus even for a large penetration depth is significantly reduced upon diffraction effects. As an illustrative example, the theoretical Raman responses for a thin coating of ~20 μm on a polymer substrate were investigated and compared to experimental results already published. Even though the interfacial region is spread over ~5-6 μm when using a 100× objective and a confocal pinhole of 200 μm diameter, it is definitively concluded that the apparent axial resolution is not drastically deteriorated with increasing depth and that the coating thickness may be directly estimated with a precision of ~1.0 μm (5%).

Citation
C. Sourisseau and P. Maraval, "Confocal Raman Microspectrometry: A Vectorial Electromagnetic Treatment of the Light Focused and Collected Through a Planar Interface and Its Application to the Study of a Thin Coating," Appl. Spectrosc. 57, 1324-1332 (2003)
http://www.opticsinfobase.org/as/abstract.cfm?URI=as-57-11-1324


Sort:  Journal  |  Reset

References

References are not available for this paper.

Cited By

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited