Holographic lenses for lighting Holography is a relatively young discipline of physics established in late 1940s. Straightforward reasons can be given to explain this late kick-off: (i) a revolutionary view of light and matter was needed, and (ii) robust and stable light sources were necessary. Everyone encounters holograms every day, for example the security marks on bank notes and credit, debit and ID cards, where you can see symbols that change as they are tilted. However, this is not all. As holography required deeper insight it also allows for unconventional optical elements, for example the “flat lens”, i.e. an un-curved, smooth and thin lens, which can be used for narrowing the beam angle in spot luminaires. Our collaboration with Dr. Norbert Tarjányi from the Department of Physics at the University of Žilina led to our first functional prototype of a holographic (positive) lens. Photos of the lens are shown in Figure 1.
Figure 1: side (left), oblique (center), front view (right) of the holographic lens.
The focusing capability of the lens was evaluated using Lumileds LEDs. The obtained footprint of green and PC-amber Rebel LEDs can be seen in the Figures 2 and 3.
lm
Figure 3: Footprint of the PC-amber LED
Figure 2: Footprint of green LED.
The performance of the obtained holographic lens is not ready for use in a luminaire. Future work is focused on improvingthe performance of holographic lenses, in particular to increase the diameter and shorten the focal length.
www.ilumtech.eu
info@ilumtech.eu