Abstract: Method of processing a photosensitive glass used in the head of an ink jet printer, including the steps of exposing the glass by a XeCl excimer laser to write a desired pattern into the front surface of the glass, with the laser emitting plural pulses to the glass and the energy of each laser pulse being 1 to 50 mJ/cm.sup.2 such that the exposed portions which will become crystallized portions do not extend through the thickness of the glass; thermally developing the exposed portions to crystallize the exposed portions; and etching away the crystallized portions so that grooves are formed in the glass according to the exposing pattern.