We’ve got an LD laser matrix with 20 blue LDs (I attached the spec). We need to diffuse the beam to spread it over 20X20cm spot at 30-50mm. We need energy density variation
I would suggest to use classical design elements of illumination optics: Collmate the laser beams with a lens array (such as in US9614348B2 Fig3), then set up an integrator (lens and rod or fly's eye) and image its output to your target area.
Henning Rehn, thank you for the idea. At first it looks very expensive but I found a way to make lenses array using a droplet method. I found these 40mm fly eyes https://www.optosigma.com/us_en/optics/lenses/fly-eye-lenses/fly-eye-lenses-FEL.html. Would they work for my application?