Monitoring the ups and downs of pulsed dye laser energy output

The internal energy meter reading of a Chromos pulsed dye laser (PDL) set at 50% of maximum pumping energy was recorded at the start of every clinical session over an 898 day period and compared with the measurement from an Ophir Optronics ‘Nova’ external energy meter. This quick and inexpensive process improved quality control procedures for the use of the PDL and enabled the performance of laser components such as the dye, pumping mechanism and optics to be monitored. The stability of the laser output energy was also monitored during three simulated clinics on days 665, 870 and 898. External energy meter readings were recorded every 100 pulses during each simulated clinic comprising six series of 500 pulses. As the energy output was shown to be stable during each clinic (SD<4.7%) recalibration during treatments of up to 500 pulses with this laser was deemed to be unnecessary. However, it was noted that this output energy stability was maintained by varying the pumping energy from 42 to 88% of maximum. Subsequent measurements of pulse width conducted with an ET-2000 Silicon Photodetector demonstrated that although the nominal pulse width was 450 μs, this varied from 240 to 390 μs as the pumping energy increased from 20 to 50%.