A tip-enhanced Raman spectrometer (TERS) has been developed based on a shear-force atomic force microscope to perform imaging and spectroscopic measurement on single wall carbon nanotubes with a spatial resolution comparable to the diameter of the tip. A radially polarized circular beam was used to generate field enhancement at the tip end resulting in more intense tip-enhanced Raman signal. Further improvement in image contrast was achieved using a radially polarized annular beam. Generation of stronger longitudinal-polarization component at the focal point led to higher field enhancement at the tip end and improved image contrast in TERS images.