Development of Hollow Light Guide for Excimer Laser Power

Abstract

The transmittance and delivery laser energy of KrF and ArF excimer lasers were improved through Hollow Light Guide with aluminum reflector. The hollow light guide uses thin polytetra-fluoroethylene (teflon) slab and polyolefin coat as its material. The size of the guide's hollow part is 8 mm width, 0.5 mm height, with 120 cm maximum length. The transmittance of KrF laser was 68%at 100 cm long. This value was higher than the previous value 50%. The maximum delivery laser energy was raised from 7 mJ to 90 mJ. In the case of ArF laser, transmittance and delivery energy was 50% per meter and 20 mJ, respectively. Their values were also higher than the previous data. The reason why the transmittance and the delivery laser energy were improved are that laser beam changed from non-polarization to linear polarization, the reflectance of aluminum reflector was high so as to devise the polishing technique, and the optimum of the coupling system were made.