Plastic light diffusers work by scattering and dispersing light from fluorescent light bulbs, creating softer, less harsh lighting. When a fluorescent light bulb emits photons, the photons travel into the diffuser. Inside the diffuser, photons interact with atoms and molecules and their paths change as a result. Because the photons are all traveling in different directions when they leave the diffuser, they provide softer lighting.
The two main types of plastic light diffusers are those made of translucent materials and those molded or carved with prismatic textures. Each type of plastic light diffuser makes fluorescent lighting less harsh, but the two types work in slightly different ways.
When light passes through a mostly clear material, such as plain glass or clean water, most photons do not interact with any molecules inside the material, and their paths stay the same. However, when light passes through a translucent material, such as frosted glass or opaque plastic, some of the photons get scattered, creating diffuse light. The more opaque a translucent material is, the more it scatters light, so heavily frosted plastic light diffusers scatter light more effectively than lightly frosted ones.
Prismatic plastic light diffusers are actually made of transparent materials, and diffuse light in a different way. When photons enter a prismatic light diffuser, they exist and re-enter the diffuser many times at many different angles due to the prismatic surface. After entering and exiting the diffuser multiple times, photons change their initial paths, and light becomes diffuse.