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Proceedings Paper

Spatial beam shaping for lowering the threshold energy for femtosecond laser pulse photodisruption
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Paper Abstract

High precision femtosecond laser surgery is achieved by focusing femtosecond (fs) laser pulses in transparent tissues to create an optical breakdown leading to tissue dissection through photodisruption. For moving applications in ophthalmology from corneal or lental applications in the anterior eye to vitreal or retinal surgery in the posterior eye the applied pulse energy needs to be minimized in order to avoid harm to the retina. However, the aberrations of the anterior eye elements cause a distortion of the wave front and consequently an increase in size of the irradiated area and a decrease in photon density in the focal volume. Therefore, higher pulse energy is required to still surpass the threshold irradiance. In this work, aberrations in an eye model consisting of a plano-convex lens for focusing and 2-hydroxyethylmethacrylate (HEMA) in a water cuvette as eye tissue were corrected with a deformable mirror in combination with a Hartmann-Shack-sensor. The influence of an adaptive optics aberration correction on the pulse energy required for photodisruption was investigated. A reduction of the threshold energy was shown in the aberration-corrected case and the spatial confinement raised the irradiance at constant pulse energy. As less energy is required for photodisruption when correcting for wave front aberrations the potential risk of peripheral damage is reduced, especially for the retina during laser surgery in the posterior eye segment. This offers new possibilities for high precision fs-laser surgery in the treatment of several vitreal and retinal pathologies.

Paper Details

Date Published: 21 September 2011
PDF: 7 pages
Proc. SPIE 8130, Laser Beam Shaping XII, 81300M (21 September 2011); doi: 10.1117/12.900598
Show Author Affiliations
Anja Hansen, Laser Zentrum Hannover e.V. (Germany)
Tammo Ripken, Laser Zentrum Hannover e.V. (Germany)
Alexander Heisterkamp, Laser Zentrum Hannover e.V. (Germany)

Published in SPIE Proceedings Vol. 8130:
Laser Beam Shaping XII
Andrew Forbes; Todd E. Lizotte, Editor(s)

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