Development of Annular Optics for the Inspection of Surface Defects on Screw Threads Using Ray Tracing Simulation

광선추적을 사용한 나사산 표면결함 검사용 환형 광학계 개발

Lee, Jiwon;Lim, Yeong Eun;Park, Keun;Ra, Seung Woo

  • Received : 2016.02.15
  • Accepted : 2016.04.24
  • Published : 2016.06.03


This study aims to develop a vision inspection system for screw threads. To inspect external defects in screw threads, the vision inspection system was developed using front light illumination from which bright images can be obtained. The front light system, however, requires multiple side images for inspection of the entire thread surface, which can be performed by omnidirectional optics. In this study, an omnidirectional optical system was designed to obtain annular images of screw threads using an image sensor and two reflection mirrors; one large concave mirror and one small convex mirror. Optical simulations using backward and forward ray tracing were performed to determine the dimensional parameters of the proposed optical system, so that an annular image of the screw threads could be obtained with high quality and resolution. Microscale surface defects on the screw threads could be successfully detected using the developed annular inspection system.


Vision inspection;Annular optical system;Omnidirectional inspection;External screw threads;Ray tracing


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