Surgery – Instruments – Light application
Patent
1993-07-27
1994-08-09
Pellegrino, Stephen C.
Surgery
Instruments
Light application
5 11, 5 17, 359379, 359676, 359809, A61B 106, F21V 704
Patent
active
053362160
ABSTRACT:
An apparatus for delivering a defocused laser beam to a sharp-edged spot (having variable size) in a target plane. The beam has a low power density in a plane of interest between the delivery apparatus and the target plane. In a preferred embodiment, the target plane is the retina of a patient's eye, and the defocused beam profile is controlled so that the beam has low power density at the eye's cornea. The beam produced by the invention is useful not only for ophthalmic surgery, but also for industrial laser heat treating and cutting applications in which a sharp-edged beam cross-section is needed at a target, particularly where delivery of low beam power densities at non-target structures are desirable. In a preferred embodiment of the inventive apparatus, an input laser beam emerges from an optical fiber, and a first lens (having short focal length) is mounted adjacent the optical fiber's output end to receive and transform the input beam. A second lens (having short focal length) is mounted with variable position between the first lens and the treatment site, for magnifying the image of the fiber core. Preferably, a lens system having long focal length (such as a pair of long focal length lenses) is mounted between the second lens and the target plane for relaying the magnified image of the fiber core to the target plane. By varying the position of the second lens and relay lens system, the characteristics of the beam delivered to the treatment site can be controlled.
REFERENCES:
patent: 3720213 (1973-03-01), Hobart et al.
patent: 4576160 (1986-03-01), Tanaka
patent: 4628416 (1986-12-01), Dewey
patent: 4776335 (1988-10-01), Nakanishi et al.
David A. Dewey, "Corneal and Retinal Energy Density with Various Laser Beam Delivery Systems and Contact Lenses," SPIE, vol. 1423, Ophthalmic Technologies, 1991, 25 pages.
Coherent Inc.
Harris Sonya C.
Pellegrino Stephen C.
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