ENHANCED CONTROL OF EXCIMER LASER PULSE TIMING USING TUNABLE ADDITIVE NOISE

Abstract

Recently we have shown a system developed to precisely control the laser pulse timing of excimer lasers [R. Mingesz, Z. Gingl, G. Almasi, A. Csengeri and P. Makra, Utilising jitter noise in the precise synchronisation of laser pulses, Fluct. Noise Lett. 8 (2008) L41–L49]. The electronic circuit based on an embedded microcontroller and utilized the natural jitter noise of the laser pulse generation to improve the long term regulation of the delay of the laser related to an external trigger pulse. Based on our results we have developed an improved system that uses additional, programmable time delay units to tune the noise source to further enhance performance and allows reduction of complexity in the same time. A mixed-signal microcontroller generates a randomly dithered delay of the pulse generation moment to enhance the resolution and also runs a dedicated algorithm to optimize regulation. The compact, flexible hardware supports further enhancements; the signal processing algorithm can be replaced even by in-system reprogramming. Optimized processing and the relaxed hardware requirements may also support low-power operation, wireless communication, therefore the application possibilities may be extended to many other disciplines.