Improving the ablation efficiency of excimer laser systems with higher repetition rates through enhanced debris removal and optimized spot pattern.
OBJECTIVE
To evaluate the reasons for the required increased radiant exposure for higher-repetition-rate excimer lasers and determine experimentally possible compensations to achieve equivalent ablation profiles maintaining the same single-pulse energies and radiant exposures for laser repetition rates ranging from 430 to 1000 Hz.


METHODS
Schwind eye-tech-solutions GmbH and Co. KG, Kleinostheim, Germany.


METHODS
Experimental study.


METHODS
Poly(methyl methacrylate) (PMMA) plates were photoablated. The pulse laser energy was maintained during all experiments; the effects of the flow of the debris removal, the shot pattern for the correction, and precooling the PMMA plates were evaluated in terms of achieved ablation versus repetition rate.


RESULTS
The mean ablation performance ranged from 88% to 100%; the variability between the profile measurements ranged from 1.4% to 6.2%. Increasing the laser repetition rate from 430 Hz to 1000 Hz reduced the mean ablation performance from 98% to 91% and worsened the variability from 1.9% to 4.3%. Increasing the flow of the debris removal, precooling the PMMA plates to -18°C, and adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the variability. Only adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the mean ablation performance.


CONCLUSIONS
The ablation performance of higher-repetition-rate excimer lasers on PMMA improved with improvements in the debris removal systems and shot pattern. More powerful debris removal systems and smart shot patterns in terms of thermal response improved the performance of these excimer lasers.
From Schwind eye-tech-solutions GmbH and Co. KG, Kleinostheim, Germany. Electronic address: samuel.arba.mosquera@eye-tech.net.
Samuel
S
Arba-Mosquera
From Schwind eye-tech-solutions GmbH and Co. KG, Kleinostheim, Germany.
Thomas
T
Klinner
D048988:Corneal Surgery, Laser / Q000295:instrumentation / Q000592:standards*; D054018:Lasers, Excimer / Q000592:standards*; D019047:Phantoms, Imaging; D019904:Polymethyl Methacrylate; D011874:Radiometry; D013696:Temperature
D019904:Polymethyl Methacrylate