Side-firing tip focuses medical laser

By: 
June 12, 1995

Foster City, CA--At first glance, endoscopy and optical fiber seem a perfect pairing of technique and technology. One provides access to remote parts of the body, the other directs laser light for surgery. The harmony ends, however, at the fiber's delivery end. There, the beam of light spills out through any of several optical tips. Few of these tips can aim the light in any direction other than straight ahead. None can focus the beam to create incisions.

Recognizing those limitations, Michael Black, a medical-device designer and president of Reliant Technologies, Inc. (RTI), spent two years developing the Laser Sweep Tip(TM)with Fiber-Optic Guide. It aims and focuses the laser beam, yet costs less than half as much as competing designs that lack these abilities.

Deceptively simple, the sweep tip contains just three components: an optical fiber, a two- or three-element optical package, and an anodized-aluminum casing. Black's patented design leverages a new process for precision-molding glass (provided by Gel Tech, Alachua, FL). The molding process dramatically reduces manufacturing costs and increases yields to nearly 100%.

The Sweep Tip squeezes all of its optical elements-either one or two lenses and a mirror-onto a single cylinder of molded glass. One end of the cylinder features a molded-in convex lens; at the opposite end is a beveled mirror, silvered on the outside.

Laser light exits the optical fiber, passes through the lens, traverses the cylinder, strikes the mirror and, depending on the design, is reflected at angles ranging from 3 to 167 degrees out of the cylinder. A second lens can be formed into the side of the cylinder at the beam's exit point. "We can mold shapes that might be impossible to grind," says Black. This method also needs little post-processing. "We mold and apply the optical coating, that's it."

The monolithic optical package mounts inside one end of a cylindrical aluminum casing 1.8 to 2.8 mm in diameter. The casing's opposite end contains threads that allow it to be screwed onto mating threads cut in the outer casing of the optical fiber.

Black's patent for the endoscopic tip includes the technique of threading it onto the fiber's case. Other manufacturers glue or crimp their devices to the case, but neither of those methods allows removal of a tip, and entire cable assemblies must be discarded after each use.

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Surgeons vary the focus by adjusting the distance from the tip to the target. At an interval of 1.0 to 1.5 mm the Sweep Tip provides a focused beam 1.5 times the fiber core diameter. Outside those dimensions, it produces a defocused beam for coagulation or ablation.

RTI received FDA marketing clearance in March. The company hopes surgeons will exploit the Sweep Tip to improve treatments ranging from heart surgery to gynecology, liver disease to urology.

Additional details...Contact Michael Black, Reliant Technologies, Inc., 1153 Triton Dr., Suite C, Foster City, CA 94404, (415) 570-6831.

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