Multi-Wavelength Raman Imaging Using a Small-Diameter Image Guide with a Dimension-Reduction Imaging Array

Abstract

A commercially available fiber-optic Raman probe was modified for high-resolution spectral Raman imaging using a 350 μm diameter optical fiber image guide coupled to a dimension-reduction imaging array (DRIA). The DRIA comprised 672 optical fibers, arranged as a square array (21 × 32 fibers) on one end and a linear array (672 × 1 fibers) on the other. An imaging spectrograph was used with the DRIA to acquire multi-wavelength Raman images from −250 to 1800 cm⁻¹ at a spectral resolution of ∼5 cm⁻¹. The utility of this technique for in situ and remote Raman imaging is demonstrated by monitoring the polymerization of a model polymer, dibromostyrene (DBS), while simultaneously measuring the Raman Stokes/anti-Stokes ratio as a function of sample heating time, over a sample area of ∼4 × 1.6 mm.