An apparatus for the treatment of a target tissue with a laser beam, said target tissue being immersed in a liquid medium within a body lumen, the apparatus comprising: a laser device for generating a laser beam; an endoscope configured to be introduced into the body lumen, the endoscope having a distal end portion; an optical fiber configured to be contained in the endoscope and having a distal delivery end for guiding the laser beam to the target tissue, wherein the distal delivery end protrudes a distance from the distal end portion of the endoscope; a controller for causing the laser device to generate one or more laser pulses substantially along the same longitudinal axis; wherein the laser device is configured to provide one or more laser pulses, the one or more laser pulses being configured by the controller to have an energy sufficient to form one or more vapor bubbles in the liquid medium at the distal delivery end of the fiber; the one or more pulses being configured by the controller to: first, cause a vapor bubble to be formed distally of the distal end portion of the endoscope and around the distal delivery end of the optical fiber; second, cause a second vapor bubble to be formed distally of the first bubble, the second vapor bubble being distal of both the endoscope distal end portion and the optical fiber distal delivery end; third, inflate the second bubble as the first bubble has begun to collapse to expand an amount sufficient to displace a substantial portion of the liquid medium from the space between the distal delivery end of the fiber and the target tissue, the one or more pulses being delivered to the target tissue through the inflated second bubble; and, wherein the displacement of the second bubble away from the distal portion of the endoscope and the distal delivery end of the optical fiber reduces wear and/or injury to one or more of the endoscope and the optical fiber. a laser device for generating a laser beam; an endoscope configured to be introduced into the body lumen, the endoscope having a distal end portion; an optical fiber configured to be contained in the endoscope and having a distal delivery end for guiding the laser beam to the target tissue, wherein the distal delivery end protrudes a distance from the distal end portion of the endoscope; a controller for causing the laser device to generate one or more laser pulses substantially along the same longitudinal axis; wherein the laser device is configured to provide one or more laser pulses, the one or more laser pulses being configured by the controller to have an energy sufficient to form one or more vapor bubbles in the liquid medium at the distal delivery end of the fiber; the one or more pulses being configured by the controller to: first, cause a vapor bubble to be formed distally of the distal end portion of the endoscope and around the distal delivery end of the optical fiber; second, cause a second vapor bubble to be formed distally of the first bubble, the second vapor bubble being distal of both the endoscope distal end portion and the optical fiber distal delivery end; third, inflate the second bubble as the first bubble has begun to collapse to expand an amount sufficient to displace a substantial portion of the liquid medium from the space between the distal delivery end of the fiber and the target tissue, the one or more pulses being delivered to the target tissue through the inflated second bubble; and, wherein the displacement of the second bubble away from the distal portion of the endoscope and the distal delivery end of the optical fiber reduces wear and/or injury to one or more of the endoscope and the optical fiber. first, cause a vapor bubble to be formed distally of the distal end portion of the endoscope and around the distal delivery end of the optical fiber; second, cause a second vapor bubble to be formed distally of the first bubble, the second vapor bubble being distal of both the endoscope distal end portion and the optical fiber distal delivery end; third, inflate the second bubble as the first bubble has begun to collapse to expand an amount sufficient to displace a substantial portion of the liquid medium from the space between the distal delivery end of the fiber and the target tissue, the one or more pulses being delivered to the target tissue through the inflated second bubble; and, wherein the displacement of the second bubble away from the distal portion of the endoscope and the distal delivery end of the optical fiber reduces wear and/or injury to one or more of the endoscope and the optical fiber.