Characterization of freeform optics in automotive lighting systems using an Optical-Geometrical Feature Based Method

L. B. Kong, Chi Fai Cheung, J. B. Jiang, Suet To, Wing Bun Lee

Research output: Journal article publicationJournal articleAcademic researchpeer-review

14 Citations (Scopus)


The use of freeform optics has been more widespread. It is difficult to evaluate the optical performance of the freeform optics due to its geometrical complexity. This paper presents a novel method named Optical-Geometrical Feature Based Method (OGFM) for the characterization of freeform optics. The method attempts to establish the relationship between the geometrical features of freeform surfaces (e.g. the surface roughness and form error) and their corresponding optical performance. Hence, the optical performance of the freeform optics can be evaluated by the measurement of the geometrical features which is relative easy to be carried out as compared to the optical performance tests conducted in automotive lighting systems. A series of simulation experiments have been conducted on the freeform optics in an automotive lighting system. The results show that the geometrical errors in micrometer scale appear not to have significant effect on the optical performance of the freeform optics. However, the optical performance is adversely affected when the geometrical form error increases from more than tens of micrometers scale to sub-millimeters scale. The successful development of the proposed OGFM provides an important means for the optimization of manufacturing tolerance, the selection of appropriate optics manufacturing process, and the evaluation of the optical performance evaluation of the freeform optics.
Original languageEnglish
Pages (from-to)358-363
Number of pages6
Issue number4
Publication statusPublished - 1 Feb 2011


  • Advanced optics manufacturing
  • Automotive lighting
  • Freeform optics
  • Geometrical features
  • Optical performance
  • Surface characterization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering
  • Atomic and Molecular Physics, and Optics


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