Methods of tolerancing injection-molded parts for illumination systems

Mark E. Kaminski, R. J. Koshel

Research output: Contribution to journalConference articlepeer-review

8 Scopus citations


Injection-molded optical components are used often for commercial illumination systems. This paper discusses methods of how to model the tolerance aspects of such components. Tolerance aspects include surface roughness, source-to-optic position and rotation errors, and surface slope errors. It is noted that all of these tolerance investigations cannot correctly account for errors in the injection-mold process. A method to model deformations induced in the injection-mold process is proposed. The method is based on the laser scan of an injection-molded part, which allows the rebuilding of the surface from the point cloud. This method, while quite accurate, is time consuming, so a second algorithm based upon approximation with a Harvey scatter model is developed that takes over an order of magnitude less in time. It is shown that the approximate model provides results within a few percent if comparisons are done in the far field. Near-field results require the rebuild method that uses the measured point cloud. Additionally, illumination systems comprising multiple interactions with the component surface (e.g., lightpipes) can use the approximate Harvey model.

Original languageEnglish (US)
Pages (from-to)61-71
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2003
EventDesign of Efficient Illumination Systems - San Diego, CA, United States
Duration: Aug 4 2003Aug 5 2003


  • Harvey model
  • Illumination
  • Injection molding
  • Nonimaging optics
  • Optical design
  • Tolerancing

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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