power amplifier pa 102 which is an excimer laser mopa 200 is nearly identical but not entirely to mopa 100 and comprises mo 201 and pa 202 which are triggered by respectively pulses 208 and 216 from high voltage pulse generators 209 and 217 both of which in turn are triggered synchronously by pulse 210 the difference between mopa 100 and mopa 200 is that the low voltage trigger pulse 210 is not synchronous with trigger pulse 110 rather trigger pulse 210 is delayed after 110 by a certain delay interval t 2 the pulse 210 is produced by splitting the output signal 150 from the low voltage pulse generator 10 into as many signals as there are mopa units for the example of fig1 the output signal 150 is split into four signals 110 250 350 and 450 as already described in the preceding paragraphs the signal 110 triggers the high voltage pulse generators 109 and 117 of mopa 100 the signal 250 goes through an electronic delay unit 260 which produces the pulse 210 that is delayed after pulse 110 by a time interval t 2 since pulse t 2 triggers the high voltage pulse generators 209 and 217 pulses in the output beam 221 of mopa 200 are delayed from pulses in the output beam 121 of mopa 100 by the same time interval t 2 we remark that electronic delay units such as 260 360 and 460 are readily available as electronic instruments that are commonly used in a like manner as illustrated in fig1 the signal 350 goes through an electronic delay unit 360 which produces the pulse 310 that is delayed after pulse 110 by.