Engineered Diffuser Technology
Thorlabs and RPC Photonics are proud to introduce a diffuser and beam shaping technology that is able to address the drawbacks of alternative technologies and to provide significant performance enhancements for applications such as lithographic systems, efficient solid-state lighting, displays, backlighting, display brightness enhancement, and projection screens.
This new concept, which we call Engineered Diffusers™, differs from other technologies in many ways. Contrary to random diffusers such as ground glass, opal glass, and holographic elements, Engineered Diffusers™ require control of each scatter center, generally in the form of microlens units. For instance, holographic diffusers can be seen as a random arrangement of lenslets. However, the lens-like features are created by the holographic exposure process and are controlled only in a statistical sense; individual microlens units are not individually manipulated, which helps to explain the inability of holographic diffusers to control light distribution and profile. In an Engineered Diffuser™, on the other hand, each microlens unit that forms the diffuser is individually specified with respect to its sag profile and location in the array. At the same time, to ensure that the diffuser is robust to input beam variations and does not produce diffraction artifacts, the distribution of microlenses is randomized according to probability distribution functions chosen to implement the desired beam shaping functions. Therefore, the Engineered Diffuser™ retains the best properties of both random and deterministic diffusers to implement general beam shaping functions with high performance.
Comparison of Engineered Diffusers with Alternative Diffuser Technologies
Commonly used diffuser technologies include prismatic glass integrating bars, ground glass, opal glass, holographic diffusers, and diffractive diffusers. Prismatic glass integrating bars, though sometimes used in high end systems, are limited in capability, are expensive, and occupy a great deal of precious space. Ground and opal glass scatter light equally in all directions but offer limited light-control capabilities. In addition, efficiency is often very poor with these simple diffusers. A holographic diffuser is a step ahead of these diffusers and enables the production of simple light distribution patterns. Holographic diffusers, however, have limited control over the light distribution pattern. In general, only round or elliptical patterns can be produced and only with non-uniform intensity variation, typically of a Gaussian nature. In terms of general beam shaping capability, diffractive elements can shape an input beam arbitrarily. These are mostly limited to monochromatic applications with coherent light sources. Diffractive elements are also limited to narrow diffusion angles due to fabrication limitations, can be strongly sensitive to input beam variations, and present the well-known problem of zero order, a bright spot co-linear with the incident beam. In many applications the zero order is unacceptable and the requirement of single wavelength operation is very restricting.
Engineered Diffusers™ provide the advanced light-control capabilities and high transmission efficiencies that most alternative diffusers cannot. Features of an Engineered Diffuser™ include the ability to spread light with specified divergence angle, control the spatial distribution of light, and control the intensity profile of the diffuse light.
For more information on the technology behind our Engineered Diffusers™, please read our Optical Diffusers Catalog Presentation.