The invention relates to a laser system (1) for the treatment of body tissue (2) on an inner circumferential tissue surface (3). The laser system (1) comprises a laser source (4) for the generation of a laser beam (5), a handpiece (6) with a treatment head (7), a control device (8) and a scanner (9). The treatment head (7) extends along a longitudinal axis (10), wherein during operation an incoming beam section (11) of the laser beam (5) enters the treatment head (7) in the direction of the longitudinal axis (10). The treatment head (7) has a conically shaped output surface (12) being disposed around the longitudinal axis (10) and having an apex (13) facing away from an origin of the incoming beam section (11). The conically shaped output surface (12) has a maximum surface radius (R). The conically shaped output surface (12) further has a half opening angle (±) being adapted to provide total reflection of the incoming beam section (11) into a reflected beam section (14) within the treatment head (7) and to provide refraction of the reflected beam section (14) into an emerging beam section (15) emerging radially from the treatment head (7) through the output surface (12). The incoming beam section (11) has at the location of the output surface (12) a mean diameter (d) being ‰¤ the difference of the maximum surface radius (R) and a minimum scanning radius (R in ). As part of the conically shaped output surface (12) a conically shaped scanning surface (38) is defined extending from the minimum scanning radius (R in ) to the maximum surface radius (R), wherein the control device (8) is adapted to control the scanner (9) for scanning at least a portion of the conically shaped scanning surface (38) with the incoming beam section (11).
