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Proceedings Paper

Adaptive optics for reduced threshold energy in femtosecond laser induced optical breakdown in water based eye model
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Paper Abstract

In ophthalmic microsurgery tissue dissection is achieved using femtosecond laser pulses to create an optical breakdown. For vitreo-retinal applications the irradiance distribution in the focal volume is distorted by the anterior components of the eye causing a raised threshold energy for breakdown. In this work, an adaptive optics system enables spatial beam shaping for compensation of aberrations and investigation of wave front influence on optical breakdown. An eye model was designed to allow for aberration correction as well as detection of optical breakdown. The eye model consists of an achromatic lens for modeling the eye’s refractive power, a water chamber for modeling the tissue properties, and a PTFE sample for modeling the retina’s scattering properties. Aberration correction was performed using 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 using transmission measurements for determination of the breakdown threshold and video imaging of the focal region for study of the gas bubble dynamics. The threshold energy is considerably reduced when correcting for the aberrations of the system and the model eye. Also, a raise in irradiance at constant pulse energy was shown for the aberration corrected case. The reduced pulse energy lowers the potential risk of collateral damage which is especially important for retinal safety. This offers new possibilities for vitreo-retinal surgery using femtosecond laser pulses.

Paper Details

Date Published: 26 March 2013
PDF: 6 pages
Proc. SPIE 8567, Ophthalmic Technologies XXIII, 85672F (26 March 2013); doi: 10.1117/12.2015298
Show Author Affiliations
Anja Hansen, Laser Zentrum Hannover e.V. (Germany)
Alexander Krueger, Laser Zentrum Hannover e.V. (Germany)
Tammo Ripken, Laser Zentrum Hannover e.V. (Germany)


Published in SPIE Proceedings Vol. 8567:
Ophthalmic Technologies XXIII
Fabrice Manns; Per G. Söderberg; Arthur Ho, Editor(s)

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