Light profile microscopy based on Raman and wavelength resolved luminescence contrast

Light profile microscopy based on contrast from wavelength resolved Raman and luminescence measurements is demonstrated experimentally for the first time. A Raman/multispectral light profile microscope (RMSLPM) has been constructed based on a line profiling geometry in which the sample is irradiated with a tightly focused laser beam (of ten micrometers radius or less) behind a polished view surface and the resulting line image is dispersed over the wavelength using an imaging spectrograph. The instrumentation developed in this laboratory has a spectral resolution approaching 10 cm(-1) and an (actual) depth independent spatial resolution of 6-8 times the Rayleigh diffraction limit, limited at present by optical aberrations and alignment. The technique has the potential to image at approximately twice the Rayleigh diffraction limit. The spectral signatures reconstructed from a variety of common industrial polymers show excellent agreement with reference spectra from the literature, and may be used to identify individual layers in depth images of unknown materials. RMS-LPM image data based on luminescence contrast have also been used to provide concentration depth profiles of additives and degradation products in injection molded samples of high-density poly(ethylene) (HDPE).