Extremely high-contrast cut-off line design with lens array

Conventionally, the optical design of a low-beam headlamp is more complex than that of general lighting systems due to the requirement of producing a high-contrast cut-off line. In this report, we present a simple yet robust design approach for bicycle low-beam headlamps using a cylindrical lens array (CLA), or lenticular lens, in combination with reflective optics. First, a reflector is employed to generate a beam with a triangular or trapezoidal intensity profile—wide at the top and narrow at the bottom. The CLA then reshapes this beam by horizontally stretching it to achieve the desired light distribution. Based on this method, we design and fabricate an LED headlamp that satisfies two vehicle headlamp regulations (K-mark and ECE R113). The proposed optical design is inherently robust, delivering a smooth and uniform light pattern while effectively mitigating artifacts and quality degradation caused by reflector fabrication errors and surface discontinuities in multi-segment designs.