In optics, a diffuser is any material that diffuses or scatters light in some manner to transmit soft light. Diffused light can be easily obtained by reflecting light from a white surface, while more compact diffusers may use translucent material, including ground glass, teflon, opal glass, and greyed glass.
Effects of a diffuser in close-up photography (for more information, see file description)
Diffuser on a camera flash. Made from a sheet of paper, a rubber band, and two staples.
A more formal diffuser filter over a camera flash, flanked by reflectors
Flash diffuser to be mounted on a camera
Ground glass is glass whose surface has been ground to produce a flat but rough (matte) finish, in which the glass is in small sharp fragments.
Ground glass stoppers