White light emitting diodes (LEDs) are considered the headlamp light source of the future. Special collimator lenses are needed to distribute and focus the light from LEDs into headlamp beam patterns. Until now, the collimators have been made of glass or polymethyl methacrylate (PMMA) plastic. Now, Bayer MaterialScience and Light Prescriptions Innovators have invested in injection moulding equipment to make high-precision collimators from Macrolon, a polycarbonate material. Collimators have free-form surfaces and are designed asymmetrically in order to focus the light coming from an LED.
The lens contains considerable jumps in wall thickness, which makes it a challenge to produce in polycarbonate material. A two-cavity tool is used, which includes a complex mechanism for tempering necessary for the double-layer injection moulding.
Polycarbonate has a higher diffraction index and is more heat resistant than PMMA, so collimators can be made with reduced thickness. They can also be made in simpler one-part designs compared with multi-element glass implementations.
The first polycarbonate collimator lenses are on the Hyundai i-mode Concept Car, which premiered at the Geneva Motor Show.
