Our damage threshold measuring station is designed according to ISO 21254: For this purpose, we have a laser available with wavelengths of 1064 nm and 532 nm, pulses of 7 ns to 10 ns, and a repetition rate of 10 Hz. On the sample, the damage profile is recorded objectively.
Preparing Measurements
Prior to each measurement, a so-called typical pulse is characterized that portrays the temporal and spatial averaging of a pulse sequence. This must meet defined stability criteria to ensure a reproducible measurement process.
Performing Measurements
The first step is to limit the energy density used for measurements, then to shoot 10 positions on the sample at the same energy density with 200 pulses, and finally to identify potential damage using a scattered light detector. The ratio of damaged spots to the number of positions in total results in the probability of damage for this energy density. This procedure increases for additional energy densities in order to obtain a characteristic damage curve. This results in the determination of the coating’s damage threshold.
