You have three types of diffusers: opal glass, ground glass, holographic. Which one is right for my application?

Edmund Optics® offers three types of diffusers. The major differences between them come down to distribution and transmission.

Distribution means the angular distribution of light as it leaves the surface of the diffuser. In other words, for each of the 180° that light can leave the surface, how much light travels in that direction. With Opal Diffusing Glass, each of the 180° gets about 1/180 of the light as it diffuses evenly in all directions. This is good for even distribution of light over a large area at a short distance. With Ground Glass Diffusers, more light goes straight through than out towards the edges which results in a bell curve shaped distribution; this is the ideal for most applications. Holographic Diffusers are specifically designed so that all the light leaves in a fairly even distribution at a specified angle. The advantage here is that by specifically designating the area of distribution, you can make the most of the light you have and not waste it at unwanted angles.

Transmission is a little more straightforward. Opal diffusing glass transmits about 30-40% of visible and NIR light. It does not transmit at all in the UV. This low transmission makes Opal diffusing glass the best choice only when you need its extremely wide and even distribution. Ground glass diffusers transmit about 40-50% of visible and NIR light and are available in UV fused silica which transmits about 40-50% of UV. The moderate transmission and distribution of ground glass diffusers make them the most popular choice for diffusers, as they are well suited for most applications. Holographic diffusers transmit greater than 85% of visible and NIR light and are also available in a UV version which transmits about 90% of UV, visible and NIR. This coupled with tightly controlled distribution make them the ideal choice for making the most of a small amount of light.