Raman Imaging of Heterogeneous Polymers: A Comparison of Global versus Point Illumination

Abstract

Two alternative methods of Raman imaging, via global (wide-field) illumination and via point illumination in combination with confocal light collection, have been applied to the study of heterogeneous polymer systems. From the results obtained it becomes apparent that the fluorescence inherent to most polymer systems severely limits the use of global illumination. Furthermore, the lack in depth resolution in Raman imaging by global illumination ruled out this method for the study of bulk polymer samples. Also as a consequence of the absence of depth resolution, the global illumination technique appeared more vulnerable to artifacts arising from scattering effects due to the sample geometry and fluorescence. Hence, for a general application of Raman imaging to the study of polymer samples, Raman imaging by point illumination in conjunction with confocal light collection is the method of choice