Glass diffusers - ground
These Ground-glass diffuser optical components are used for scattering incoming light and reduce directionality in the beam. Ground Glass Diffusers give a diffusion angle of ± 10º and are useful for focusing screens and for weak diffusion in illumination systems. Ground Glass Optical Diffusers are listed with three available materials components, LEGB, B270 and UV Fused Silica
Anti-Newton glass is also listed here which gives the weakest diffusion effect. This lightly-etched glass is used to support film enlargers etc. without interference rings (Newton’s rings) appearing.
Flashed Opal diffusers
These Opal Diffusers "White flashed opal", has a nearly lambertian characteristic (luminance independent of viewing angle). However because opal glass has a high degree of scatter it is very wasteful of energy. Scientific components such Opal Diffusers are useful in light boxes and illumination systems where strong diffusion is required.
These Plastic Screens have still greater diffusion than ground glass optical components, allowing an image to be back-projected on a large screen without `hot spot’, and have a grey tint to minimise reflection of ambient and scattered light. The 0.3mm PVC material, with a gain of 2.3, is normally stretched over a component rigid frame, where as the 3mmm acrylic (with gain of 3) is self-supporting.