FIELD OF THE INVENTION

A process is described for blocking errant and potentially damaging pulse energies, generated as the laser pump source(s) and/or the optical gain medium stabilize or equilibrate to operational conditions, from coupling to optical fiber energy delivery devices, reducing damage to optical fiber coatings and lowering the minimum bend radii for safe delivery of therapeutic energy. Methods of implementation of the strategy are discussed.

BACKGROUND

Lasers find utility in a variety of applications where significant pulse energies or laser powers are delivered by means of optical fibers. A limitation to delivery of laser power or energy by optical fiber is the minimum bend radius of the fiber where energy loss within the bend is sufficient to initiate catastrophic failure. This minimum optical bend radius is typically dependent upon the wavelength of the laser, the average power or peak pulse energy and repetition rate of the laser, the size and the construction of the optical fiber.

Small optical fibers are often called upon to deliver pulse laser energy to kidney stones while passing through highly deflected flexible ureteroscopes. A common failure mode of fibers within flexible ureteroscopy is popularly described as “burn through”, where the fiber suddenly fractures within the scope forceps channel. Such failures are a leading cause of costly scope repairs and have even been known to injure patients by burning through the damaged scope wall.

Another failure that is similar to that described above is caused by gripping the fiber to control its position within the patient; if minimum optical bend radii are exceeded, the fiber burns through and injures the surgeon.

SUMMARY

The initial output of high power lasers is often uncharacteristically high in power or energy and/or low in M2beam quality and hot spots; light that, if coupled to an optical fiber that is at or near the optical minimum bend radius, damages the optical fiber such that subsequent, more characteristic laser emission is less competently contained than it would otherwise be had the damage been avoided. The invention described herein provides methods for avoiding fiber damage from uncharacteristic initial laser emissions, thereby enabling safer and more effective use of fiber optic laser energy delivery systems in tortuous confines such as found in ureteroscopic laser lithotripsy.

A first embodiment is a process that can include initiating, at an initiation time, a beam along a beam path from a laser source to an optical fiber; attenuating the beam reaching the optical fiber for a period of time (T1) from the initiation time; then ending the attenuation of the beam while continuing to provide the beam along the beam path.

A second embodiment is a surgical laser system that can include a laser source optically coupled to an optical fiber; a beam attenuator configured to attenuate a beam from the laser source to the optical fiber; and a controller configured to adjust a quantity of beam attenuation.

A third embodiment is a surgical laser system that can include a laser source optically coupled to an optical fiber, the laser source including a laser rod and a pump source; a beam attenuator configured to limit a transfer of energy from the pump source to the laser rod thereby attenuating a beam from the laser source to the optical fiber; and a controller configured to adjust a quantity of beam attenuation.

