Single-pulse laser ablation of polyimide was investigated by using focusedUV-Ar+-laser radiation(&lgr;≈302 nm,140 ns⩽&tgr;l⩽50 ms)and atomic force microscopy. The results clearly demonstrate that the ablation rates donotdepend on the total dose only, but depend as well on the duration of the laser pulses,&tgr;l.The experimental results can be interpreted almost quantitatively on the basis of a purely thermal model. ©1998 American Institute of Physics.