Lenses and mirrors are the traditional tools employed for creating directional beams, while simple diffusing materials are found wherever a uniform spread of light is called for. However, the efficiency of many optical control elements leaves a lot to he desired. Take fibre optic lighting as an example. The reason for its expense and inefficiency is that we struggle to build optical systems that can collect light efficiently from a lamp and inject it into the fibres. Similarly, the illumination of areas with total uniformity is difficult because the diffusing materials employed tend to absorb much of what they scatter. It is in this latter category that light shaping diffusers look set to radically change the way we deliver light uniformly over any given area, be it a mobile phone screen or across a football stadium.
Light shaping diffusers (LSDs) are remarkable structures that are holographically recorded with a randomised surface. They excel in three main areas high transmission efficiency, virtually unlimited beam shaping capability and total homogenisation of light. The list of applications seems endless, but first let's take a closer Iook at LSDs.
Manufactured from thin polycarbonate or polyester sheets, LSD’s have a very special pattern embossed into one side of the film. The holographically generated texture is completely randomised and this is what makes them such excellent diffusers. It ensures that they are not dependent on the wavelength of light, and that they work just as well on anything you point at them. You will get the same effect whether you use a laser pointer, an ordinary spotlight beam, or a 3,000W lighthouse beacon.

Applications

Taking the most elementary situation in which you would use a simple LSD in place of, say, a frosted glass plate, the LSD will deliver the same effect but with phenomenally high efficiency of light transmission. Ground glass and plastic diffusers, typically, let through 65 per cent of the light directed at them, so every time you try to get a soft lighting effect this way you can instantly say goodbye to a massive proportion of your light. By contrast, LSDs transmit up to 92 per cent of the incident radiation. Quite remarkable is the fact that they actually transmit more light than the material from which the film is made. The substrate only transmits 89 per cent light, however the holographically recorded surface has special antireflection properties, which coax more light to enter the material.
LSDs are offered in thin sheet form and come in a variety of diffusion angles from 0.2 90 degrees, depending on how much diffusion is required. The lower diffusion angles are particularly suitable for homogenising a beam of light and the illustrations (above) show how they remove hotspots and dark rings in the beam of a flashlight and an LED, as well as the homogenising effect on a filament image.