From Light Blade to Lens: Optical Plastics in Action

Over two meters long, weighing almost two kilograms, molded in a single shot – and certainly not made of glass: how optical plastics are shaping vehicles, luminaires, and displays today is best illustrated by concrete components.

These highly transparent plastics – above all PMMA (acrylic glass) and polycarbonate – have long since moved out of the lab and into series production. Three examples show how differently they are used: in automotive lighting design, in general lighting, and in headlights.

A good example is the "light blade" at the rear of the Lucid Gravity: more than two meters long, weighing almost two kilograms, and – according to Röhm – the world's largest single-piece taillight at the time of the award. Supplier FORVIA HELLA molds the component in a single operation from PLEXIGLAS, Röhm's branded PMMA. In 2024, it won first prize at the SPE Automotive Award (Electronical/Optical Part category). According to the manufacturer, two properties are key: the plastic guides light along its full length, and it is so UV- and weather-resistant that the light graphic is designed to retain its true color throughout the car's lifespan. 

The trend is moving toward continuous light bands spanning the full width of the vehicle, illuminated logos, and ambient lighting in the interior. PMMA is used, for example, in the slim rear light graphic of the new Mercedes-Benz CLA, the saber-shaped taillight of the electric SUV IM LS7, and the illuminated emblems of the Opel Grandland Electric, CUPRA Tavascan, and SEAT – with SEAT even featuring colorfully illuminated air vents. How such a component is made could be seen at K 2025: at the booth of machine manufacturer ENGEL, an 850-millimeter-wide cover was produced using in-mold decoration (IMD), in which a functional film is embedded directly into the plastic within the mold. The film comes from manufacturer Leonhard Kurz – one example of how closely material, machinery, and finishing now work together.

A second field of application is professional lighting. Here, what matters most is how cleanly and clearly the plastic transmits light. Luminaire manufacturer Zumtobel produces the lenses for its TECTON light band system from PLEXIGLAS; according to the company, more than 39,000 kilometers of it have been installed worldwide. For the second generation of the device, "the high optical purity and the very high molding accuracy in injection molding" were decisive, says Global Product Manager Maximilian Macha. According to Röhm, the material transmits up to 92 percent of light.

This allows light to be directed precisely: so-called double-split lenses distribute it in a largely glare-free way across four different beam widths – from a wide angle for open areas to a narrow beam for tall shelving aisles. Together with a matching LED driver, the system achieves, according to Zumtobel, up to 210 lumens per watt and a service life of 100,000 hours. For applications with high continuous heat, there is the special grade PLEXIGLAS Optical HT, from which Lena Lighting produces the lenses for the Tiara LED Pro street light.