A ureteroscope for dusting stones in a body cavity with a laser fiber , the ureteroscope comprising: a flexible probe comprising a proximal end and a distal end , the flexible probe comprising: a working channel configured to accommodate the laser fiber in the distal end of the flexible probe at a working position, the laser fiber to be deflected against a target stone for dusting, the working position being a predefined distance of the laser fiber from the distal end of the flexible probe and defined by laser energy settings and composition of the target stone; and a handle extending proximally from the flexible probe , the handle comprising: a plurality of control switches configured to provide digital control signals, the digital control signals configured to control a motor assisted movement of the laser fiber in the working channel by a user, the motor assisted movement of the laser fiber comprising one of a feeding movement and a retracting movement; and a laser fiber feeder and retraction module configured to control one of the feeding movement and the retracting movement of the laser fiber in the working channel , the feeding movement of the laser fiber comprising a forward movement of the laser fiber in a first rotating direction, and the retracting movement of the laser fiber comprising a backward movement of the laser fiber in a second rotating direction. a flexible probe comprising a proximal end and a distal end , the flexible probe comprising: a working channel configured to accommodate the laser fiber in the distal end of the flexible probe at a working position, the laser fiber to be deflected against a target stone for dusting, the working position being a predefined distance of the laser fiber from the distal end of the flexible probe and defined by laser energy settings and composition of the target stone; and a handle extending proximally from the flexible probe , the handle comprising: a plurality of control switches configured to provide digital control signals, the digital control signals configured to control a motor assisted movement of the laser fiber in the working channel by a user, the motor assisted movement of the laser fiber comprising one of a feeding movement and a retracting movement; and a laser fiber feeder and retraction module configured to control one of the feeding movement and the retracting movement of the laser fiber in the working channel , the feeding movement of the laser fiber comprising a forward movement of the laser fiber in a first rotating direction, and the retracting movement of the laser fiber comprising a backward movement of the laser fiber in a second rotating direction. a plurality of control switches configured to provide digital control signals, the digital control signals configured to control a motor assisted movement of the laser fiber in the working channel by a user, the motor assisted movement of the laser fiber comprising one of a feeding movement and a retracting movement; and a laser fiber feeder and retraction module configured to control one of the feeding movement and the retracting movement of the laser fiber in the working channel , the feeding movement of the laser fiber comprising a forward movement of the laser fiber in a first rotating direction, and the retracting movement of the laser fiber comprising a backward movement of the laser fiber in a second rotating direction. <EOS>