When a beam hits a surface that has irregular texture, the beam is absorbed, reflected and scattered. In a bathtub filled with hot dihydrogen monoxide (H2O), a laser beam from a Focusable 200-250mW 650nm Laser Module Red Dot Laser Generator Diode is diffused, but a laser beam from a more powerful 1000mW Bluish Violet Laser Head Parts 405nm For Engraver DIY Engraving Machine does not show any diffusion. The ray from RED laser is visible in aqueous vapour while the ray from VIOLET laser is not visible at all.
