Engineered Diffusers are advanced optical diffusers that are much more versatile than conventional diffusers.
With an engineered diffuser the beam radiance distribution can be changed into a distribution that is more uniform or homogeneous and in which light does not spread beyond the areas of interest.
This beam characteristic is better fitting to a vast majority of laser applications, be it in industry or in the medical field.
Depending on the type of input light, engineered diffusers can be of two families, which are the following:
- Broadband Diffusers
- Diffractive Diffusers
These two families of Engineered diffusers differ mainly in the operating principle behind each one. On the one hand, broadband diffusers are similar to micro lens arrays so their performance can be explained following the principles of ray theory.
Thus, the chromaticity, although it is present, is of minor concern. Thus, broadband diffusers are used when the input light is polychromatic.
A broadband diffuser is different from a micro lens array in that in the former the radius of curvature varies along the lenslet array. Thus, the shape of the final beam can be controlled with more accuracy.
The other type of engineered diffusers is the diffractive diffuser which works by harnessing the wave nature light. In other words, as its name implies, the input beam is altered by means of diffraction which can be regarded as a special case of self-interference.
Given the high chromaticity that is inherent to diffractive optical elements, diffractive diffusers are used only when the input light is monochromatic as it is the case of beams from laser systems.
The main use for engineered diffusers is as beam homogenizers. The input light beam traverses the engineered diffusers and then at the output plane a new beam distribution appears, and it covers a larger area and with good uniformity.
This sort of transformation is desirable, for example, in skin treatment in medicine. In this case the laser system will need less time as the treatment speed will be increased.
At the same time, the risk of inflicting harm like burning of the skin is also reduced due to the beam spread and the elimination of any hot spots on the original input beam.
Engineered diffusers can also be used with very high power laser systems such as annealing systems, surface hardening systems and other thermal treatments.
In this case the engineered diffuser is equipped with efficient anti reflective coatings that increases the throughput of the process while reducing the danger of high power reflected beams .
