A special man-made 2-D bar code ruler is applied to the CCD image measurement of 2-D micro-displacement of close quarters object in this paper. The bar code ruler is a set of concentric annulus in which the widths of them are based on cosine rule. In measuring process, the ruler is attached to the object, moving with it, and the relatively fixed CCD collects the image data of the bar code before and after the movement. From analysis of phase shifts of those image data, we can get the measuring results. Besides that the measurement precision is affected by quantization, the size of pixels and interspaces between pixels, there are other factors which can cause distorted image data and in turn result in errors in results. By comparison of the decussating form and the concentric annular form of the bar code, we can see that though not all the image data of the whole annulus make contribution to the calculation of phase shifts, the latter form plays a great role in practical application for it ensures the precondition which makes it possible to get correct measurement and detect the distorted image data.

Date Published: 20 September 2002
PDF: 6 pages
Proc. SPIE 4919, Advanced Materials and Devices for Sensing and Imaging, (20 September 2002); doi: 10.1117/12.471897

Published in SPIE Proceedings Vol. 4919:
Advanced Materials and Devices for Sensing and Imaging
Jianquan Yao; Yukihiro Ishii, Editor(s)