POTASSIUM VAPOR NEAR-IR LASER LINE REJECTION FILTER FOR RAMAN-SPECTROSCOPY

A simple, inexpensive, near-IR laser line rejection filter using potassium vapor is described and characterized for Raman applications. Stokes and anti-Stokes Raman spectra, including the laser wavelength, were collected with the use of this filter. The cystine 9.6-cm-1 anti-Stokes band and the 14.9-cm-1 Stokes band were only weakly affected by the vapor filter, but the laser line was attenuated by more than 10 orders of magnitude. The laser line was completely removed from the spectra of weak elastic scatterers without significantly attenuating emission +/-1.2 cm-1 from the laser line.