This letter demonstrates how the use of an annular beam can significantly reduce the detected fluorescence from optical components within a Raman spectroscopic arrangement. The fluorescence from the excitation beam has a reduced generation and collection efficiency compared to the standard Gaussian beam. Crucially, the Raman signal from the annular beam is collected through the dark center of the excitation light field. This robust and simple technique may be immediately applied to all Raman configurations and may find broader applicability for any spectroscopic methodology which utilizes a high numerical aperture lens and requires the detected fluorescence to be suppressed.
Bibliographical noteFunding Information:
This work was supported by the U.K. Engineering and Physical Sciences Research Council and the Scottish Higher Education Funding Council. One of the authors (I.G.C.) acknowledges support from the International Human Frontier Science Program.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)