Abstract

Automated assembly and quality control require reliable systems for the detection of the position and the orientation of complicated objects. Correlation methods are well suited, but they are affected by structured backgrounds, varying illumination conditions, and textured or dirty object surfaces. Using fringe projection to exploit the three-dimensional topography of objects, we improve the performance of a nonlinear joint transform correlator. Positioning of noncooperative objects with subpixel accuracy is demonstrated. Additionally, the tilt angle of an arbitrarily shaped object is measured by projection of object-adapted fringes that produce a homogeneous fringe pattern in the image plane. An accuracy of better than 1° is achieved.

© 1998 Optical Society of America

Fringe-adjusted joint transform correlation

Mohammad S. Alam and Mohammad A. Karim
Appl. Opt. 32(23) 4344-4350 (1993)

Three-dimensional joint transform correlator

Joseph Rosen
Appl. Opt. 37(32) 7538-7544 (1998)

Grazing holographic projection of object-adapted fringes for shape measurements with enhanced sensitivity

E. U. Wagemann, M. Schönleber, and H.-J. Tiziani
Opt. Lett. 23(20) 1621-1623 (1998)

Distortion-invariant fringe-adjusted joint transform correlation

Mohammad S. Alam, Xue-wen Chen, and Mohammad A. Karim
Appl. Opt. 36(29) 7422-7427 (1997)

Improved feature extraction by use of a joint wavelet transform correlator

Boon Yi Soon, Mohammad S. Alam, and Mohammad A. Karim
Appl. Opt. 37(5) 821-827 (1998)