The design of critical automotive lamp reflectors, e.g. headlamps and fog lamps, is dominated by trial-and-error methods and rules-of-thumb, supported by optical ray-tracing tools like ASAP etc. In many cases these reflectors are designed by aiming small sections to construct the required illumination distribution, which is a time-consuming task and in which case it is very difficult to maintain a continuous reflector surface. The design method presented here is a more structured approach in which the total available front surface is divided in a few relatively large sections, each section designated to produce a certain part of the required light distribution. An optimizing algorithm is used to optimize the separate polynomial reflector sections in combination with a specific burner. In the final step, the separate sections are put together to form a more-or-less continuous reflector surface. Some iteration afterwards is still required because the intersection lines of the polynomial surfaces will generally change the original section boundaries. The design of a front fog reflector lamp is used as a carrier to demonstrate the approach. Three reflector sections are used to design a high-efficiency fog lamp. The light distribution has an excellent horizontal cut-off that basically meets the SAE requirements.

Date Published: 3 November 2003
PDF: 9 pages
Proc. SPIE 5173, Current Developments in Lens Design and Optical Engineering IV, 517306 (3 November 2003);

Published in SPIE Proceedings Vol. 5173:
Current Developments in Lens Design and Optical Engineering IV
Pantazis Z. Mouroulis; Warren J. Smith; R. Barry Johnson, Editor(s)