Reduction of systematic errors in structured light metrology at discontinuities in surface reflectivity. (January 2019)

• Record Type: Journal Article
• Authors: Yue, Huimin; Dantanarayana, Harshana G.; Wu, Yuxiang; Huntley, Jonathan M.
• Is Part Of: Optics and lasers in engineering. Volume 112(2019)
• Page Start: 68
• Page End: 76
• Publication Date: 2019-01
• Subjects: Projected fringes -- Profilometry -- Edge detection -- Systematic errors -- Point spread function; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2018.08.002
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: Shape measured by structured light has large errors near jumps in reflectivity. Error source is imperfect fringe averaging within the camera's point spread function. Correction algorithm proposed; systematic errors reduced by up to 3×. Abstract: In measuring 3D shape with structured light techniques, systematic errors arise in the neighbourhood of discontinuities in reflectivity or geometry. A mechanism for this phenomenon is proposed, based on the finite size of the imaging system's point spread function. A theoretical analysis for the phase errors in a phase-shifting projected fringe system is given, from which a correction algorithm to minimise the systematic errors is presented. In this algorithm, a closed form expression for the errors based on the intensity values and the phase values in a neighbourhood excluding the affected region is used to remove the estimated error from the measured phase values within the affected region. Experiments on samples with both linear and circular discontinuities in reflectivity demonstrated respective reductions in systematic errors by factors of 2.5× and 3×.