The damage produced in silicon carbide single crystal by ion implantation was investigated by in situ optical transmittance and reflectance at 633 nm and by Rutherford backscattering channeling spectroscopy. Implantations were performed at room temperature with different ions (He, N, Ar, Kr, and Xe) in the fluence range 1011–2.5×1016 ions/cm 2. During irradiation a reduction of transmittance and a contemporary increase of reflectance occurred. RBS indicated a continuous accumulation of damage within a depth comparable with the ion range until the formation of an amorphous layer. A combination of optical and RBS data allowed to correlate the optical constant (n,k) to the damage produced during irradiation. Such a correlation was identical for every ion pointing out that the optical properties of the damaged material are independent of the energy density inside the single cascade. © 1996 American Institute of Physics.