Research on Optimizing Cutting Proecesses on Materials for Intra-Ocular Lenses

After a short introduction about expected ablation processes and thoroughly literature research on the results of previous publications and the preliminary work about ablation of IOL materials first estimations are made. Under considertion of the absorption of different materials in IOL several processing wavelenghts are chosen. CI26 as well as CI26Y are studied.

As short chemical view on polymer ablation is presented. The results of this overview show, that - in case of carbonization - oxygen as process assisting gas could lead to well improvements. Since no carbonization could be detected at adequate processing paramters this had not yet been implemented. For more explicit information, a detailed chemical analysis of the produced cuts has to be done.

To make further experiments possible an adaptable sample holder has been designed and built. It does not only allow reproducible tests, but also can be used a process atmosphere chamber with different process gas flows or vacuum processing.

Over 200 documented single cutting tests, where only the most important are mentioned in this thesis, were exectued and analyzed. Several test series have been studied to achieve bst possbile working parameters for fs and ps laser ablation of IOL materials.

In 800 mm fs laser ablation applicable results for opal edges are presented. Due to the long fabrication time of over 30 seconds it is reommended to use ps laser blation. For completely clear transparent cutting edeges the fs laser can be used at 266 nm. Unfortunately this results in the given setup at extremly long fabrication times per lens of over 15 minutes.

Pico second laser ablation has been studied more detailed, what is also a result of the options provided by the laser systems. It can be concluded that ablation at nearby no pulse overlap leads to the most homogeneous edges. By applying multiple cutting techniques and optimizing the lateral displacement of the cuts, perfectly opal edges can be produced. The cutting angle can be reduced by adequate cutting repetitions and displacement size. The theoretical fabrication time for one intra ocular lens can be driven down to 2 seconds. Due to software compatibility issues no completely produced lens is being presented. Though, a partial practicability is shown by cutting out the end of the haptics.

As option processing possibility surface fusing is being studied. Applying experiences of the fast feed motion processing, the plasma bulge can be minimized and a macroscopic transparent fused surface is produced.

As next steps research on low cost ps laser systems could be advidable to quantify economic feasibility. Similarly there should be future research on fs laser ablation of IOL materials in focus on high quality lenses.