Design of Intra-Tissue Refractive Index Shaping Systems and Their Implementation in Creating Refractive Structures in Live Cats

摘要

This thesis presents work done on the development of systems for performing intra-tissue refractive index shaping (IRIS) with an emphasis on their application to live cats. IRIS is a novel process by which a femtosecond laser is focused into a material, causing changes in the refractive index (RI) of the material below the laser power damage threshold. This process is caused by nonlinear absorption and so is localized to the higher intensity region within the focal volume. By scanning the region through a material, a spatially varying RI pattern can be created. This spatially varying RI can be tailored to create refractive devices.;The focus of this thesis is on the discussion of the various parameters that affect the resulting optical phase change induced by IRIS and how they impact the design of systems for creating refractive structures with IRIS. A novel IRIS system will be presented that represents a significant advancement of the capabilities of IRIS. This system is comprised of five different subsystems: the laser source, in-process laser power control, dispersion compensation, beam shaping, and focal region scanning. The final scanning system uses a new, custom flexure-based scanning head for high-speed translation of the focal region through a stationary material, critical for clinical application of IRIS as a new method of laser refractive correction.;The culmination of this work is the successful creation of 6 mm diameter cylindrical Fresnel lenses in live cats using IRIS. Using all of the advances in IRIS system design and learning from preliminary in vivo results from a prototype system, three eyes were successfully written in vivo in cats using IRIS. Up to -1.4 +/- 0.17 D of cylinder was induced in a cat eye with -0.29 +/- 0.23 D of defocus. Measurements were taken over 6-12 months and were stable over that timeframe.;Finally, a novel system for performing IRIS in contact lenses with the application of contact lens customization will be shown. This system will center around the design of a curved image plane objective and full-field optical scanning.