Hollow waveguide delivered infrared free electron laser for microsurgical applications
The Free Electron Laser (FEL) at Vanderbilt University is tunable from 2 μm to 9 μm in the mid-infrared spectrum, which is capable of controlling predicted laser-tissue interaction by selecting a specific wavelength. However, delivery of this laser into the internal portion of the eye is difficult because of strong water absorption at this spectrum range and the high peak power of the FEL. We used a metallic coated hollow waveguide with a 530 μm inner diameter and 1 meter in length, and delivered the FEL beam to an autoclaved surgical probe. The probe tip was an 18 gauge canula with a mini CaF2 window fixed in front of it to protect the waveguide from contacting water. Human and animal cadaver eyes were used to perform an open sky retinal cutting procedure. The system was able to deliver 60% of FEL energy to the intraocular tissues. Up to 6×105 w peak power was reached without damage to the waveguide or the surgical probe at the spectrum range of 2.94 μm to 7.7 μm. In conclusion, the hollow waveguide is suitable for delivering the infrared FEL for intraocular microsurgical procedures.
