a 1 . 4 - 1 . 6 mm diameter microendoscope is introduced into a duct leading to the submaxillary or parotid glands containing a concrement . the endoscope is adapted to contain a working channel , an image bundle , a light bundle and a wire , all structure fixedly spaced apart within the microendoscope . a laser fiber is inserted into the working channel to the concrement and the concrement is fragmented with a laser shock wave while flushing the fragments away through the working channel .