System and method for scanning a pulsed laser beam

摘要

Systems and methods of photoaltering a region of a material using a pulsed laser beam. The method includes scanning the pulsed laser beam in a first portion of the region with a first pattern, scanning the pulsed laser beam in a second portion of the region with a second pattern, and separating a flap of the material at the region. The system includes a laser, a controller selecting at least first and second patterns, and a scanner operable in response to the controller. The first pattern has a first maximum acceleration associated with the second portion, and the second pattern has a second maximum acceleration associated with the second portion. The second maximum acceleration is less than the first maximum acceleration. The scanner scans the pulsed laser beam from the laser in the first portion with the first pattern and in the second portion with the second pattern.

主权项

1. A method of photoaltering a sub-surface region of a patient's cornea using a pulsed laser beam to create a corneal flap, the sub-surface region having an outer periphery, a first portion defined within and circumscribed by the periphery, and a second portion smaller than and located within the first portion, the method comprising the steps of:
transmitting the pulsed laser beam with a scanner having a mass in the first portion of the sub-surface region with a first scan pattern defined over a dome-shaped area in the cornea, the first scan pattern requiring a first maximum scanner mass acceleration when traversing the region, wherein the first scan pattern comprises scanning the pulsed laser beam in a spiral pattern beginning from the periphery of the region and successively tracing smaller rotations toward the second portion to permit sufficient time for ablation gas to either cool down or to migrate away before the next inward rotation of the spiral pattern so as to reduce and/or eliminate formation of an opaque bubble layer (OBL) in a corneal flap bed; transmitting the pulsed laser beam with the scanner in the second portion of the sub-surface region with a second scan pattern defined over the dome-shaped area in the cornea, the second scan pattern requiring a second maximum scanner mass acceleration less than the first maximum scan acceleration, wherein the second scan pattern comprises scanning the pulsed laser beam in a raster pattern; and separating a corneal flap at the region.