I am trying to use an Nd:YAG laser for pulsed laser melting My laser is an EKSPLA NL313, which has a 5 ns pulse. I need to produce a decent size spot (~1 cm2) with a fluence of about 1 J/cm2 for the laser melting, which is no problem with this laser. However, the spot needs to be very uniform in intensity. The YAG laser has very good spatial and temporal coherence, which means that the spot has a lot of speckle. I have looked at several solutions, but I am having trouble getting anything to work in practice. I have tried using an engineered diffuser, and this works to a certain extent, but there are still unacceptable variations in the intensity. I have tried using a beam homogenizer, but I still end up with fringes in the spot, almost like the beam was just folded back onto itself. This may be due to the fact that the spot is circular, while the homogenizer is rectangular. I have also tried using a pinhole to eliminate spatial harmonics, which also kind of works, but not well enough. I still have some fringes. Basically, I have tried several solutions, but none of them is getting me where I need to be. I have looked at using custom microlens arrays, but the high cost and lead time (6 months) makes that impossible. Does anyone know of a way I can homogenize the beam? Is there a combination of elements I could use to do this?