LEDs have replaced nearly all different kinds of traditional light sources. The reason is quite simple: LED illumination fulfills customer requirements in terms of efficiency, size and longevity. Nevertheless, with LED new topics arise for optic manufacturers. LED optics require special handling of lighting mixing and diffusion for smooother light distributions and a better color mixing. One approach, especially when used with refractive optics, is an adapted surface treatment which can be realized both as rough or periodic structures. We offer both methods to our customers:
Rough surfaces can be realized with sandblasting or electrical discharge machining. Both the tools for glass production and the final glass part can be treated.
For better light control we also offer surface structures build up by regular or quasi-regular arrangements of spherical scatter elements.
For hot-forming, where glass is pressed from the liquid phase, we can realize gratings with lattice constants down to 500 μm. Typical surface deviations are in the range of 5 μm, which allows for good light control.
Figure 1: Directly pressed micro structure: hexogonal grating with lattice constant of 500 μm. Microscope image of the surface. False color diagram of surface profile.
We also implemented a post processing, where surface structures are imprinted onto the glass surface. With this technology we are able to replicate lattice constants below 50 μm and surface deviations of only 1 μm.
Figure 2: Imprinted micro structure: semi random arrangement with average distance of 50 μm. Microscope image of the surface. False color of surface profile.
Surface structuring fetches plenty of interest in the market as there are many applications: lenses with smooth light distributions, diffusion disks for LED/laser and light guides with superior color mixing.