Ultrahigh mol. wt. polystyrene-b-polyisoprene block copolymers (BCs), noted for their photonic behavior, were imaged using transmission near-field scanning optical microscopy (NSOM) and NSOM polarimetry. The authors' improved scheme for polarization modulation (PM) polarimetry, which accounts for optical anisotropies of the NSOM aperture probe, enables mapping of the local di-attenuation and birefringence (with sep. aligned di-attenuating and fast axes) in these specimens with sub-diffraction limited resoln. PM-NSOM micrographs illuminate the mesoscopic optical nature of these BC specimens by resolving individual microphase domains and defect structures. [on SciFinder(R)]