Illumination system development using design and analysis of computer experiments

Janos C. Keresztes, Bart De Ketelaere, Jan Audenaert, Richard John Koshel, Wouter Saeys

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

Computer assisted optimal illumination design is crucial when developing cost-effective machine vision systems. Standard local optimization methods, such as downhill simplex optimization (DHSO), often result in an optimal solution that is influenced by the starting point by converging to a local minimum, especially when dealing with high dimensional illumination designs or nonlinear merit spaces. This work presents a novel nonlinear optimization approach, based on design and analysis of computer experiments (DACE). The methodology is first illustrated with a 2D case study of four light sources symmetrically positioned along a fixed arc in order to obtain optimal irradiance uniformity on a flat Lambertian reflecting target at the arc center. The first step consists of choosing angular positions with no overlap between sources using a fast, flexible space filling design. Ray-Tracing simulations are then performed at the design points and a merit function is used for each configuration to quantify the homogeneity of the irradiance at the target. The obtained homogeneities at the design points are further used as input to a Gaussian Process (GP), which develops a preliminary distribution for the expected merit space. Global optimization is then performed on the GP more likely providing optimal parameters. Next, the light positioning case study is further investigated by varying the radius of the arc, and by adding two spots symmetrically positioned along an arc diametrically opposed to the first one. The added value of using DACE with regard to the performance in convergence is 6 times faster than the standard simplex method for equal uniformity of 97%. The obtained results were successfully validated experimentally using a short-wavelength infrared (SWIR) hyperspectral imager monitoring a Spectralon panel illuminated by tungsten halogen sources with 10% of relative error.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSPIE
Volume9579
ISBN (Print)9781628417456, 9781628417456
DOIs
StatePublished - 2015
Event18th Conference of Novel Optical Systems Design and Optimization - San Diego, United States
Duration: Aug 10 2015Aug 12 2015

Other

Other18th Conference of Novel Optical Systems Design and Optimization
Country/TerritoryUnited States
CitySan Diego
Period8/10/158/12/15

Keywords

  • computer experiments
  • fast flexible designs
  • Gaussian Kriging model
  • Gaussian Process
  • illumination design
  • non-imaging optics
  • optimization
  • SWIR hyperspectral imaging.

ASJC Scopus subject areas

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

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