The optical penetration depth for polycarbonate (PC) at 308 nm due to XeCl laser is about 450μm while those of KrF (248 nm) and ArF (193 nm) lasers become noticeably shorter to 1μm and 20 nm, respectively, to show the strong superficial absorption at shorter UV wavelengths. On the other hand, KrF laser exposure on polycarbonate, at doses above 6J/cm2, creates the surface crosslinking. In spite of several reliable methods available, such as "hot set" and "gel content", to determine the bulk crosslinking, there are a few consistent techniques to evaluate the surface crosslinking effect quantitatively. It includes hardening measurements using nanoindenter or AFM (atomic force microscopy). In this work, we present a technique for the measurement of superficial crosslinking, based on electrochemical etching of alpha irradiated polycarbonate accordingly. The mean diameter of the developed tracks nonlinearly decreases for KrF laser treatment at higher doses. The relative shrinkage of track diameters due to UV exposure before alpha irradiation, comparing to those without UV pre-radiation, indicates that UV laser makes the polymer surface hardened. The variation of mean track diameters can be strongly used to quantify the surface crosslinking. © 2005 Elsevier Ltd. All rights reserved.