Diffuser (optics)

It uses diffraction to manipulate monochromatic light, giving it a specific spatial configuration and intensity profile.

Diffractive diffusers are commonly used in commercially available LED illumination systems.

Usually, the diffuser material is GaN or fused silica with processed rough surfaces.

When used in front of the camera lens, a diffusion filter softens subjects and generates a dreamy haze.

This effect can also be improvised by smearing petroleum jelly on a UV filter or shooting through a nylon stocking.