Study of vision reading system based on digitized ruler

A machine vision reading system is designed in order to improve the performance of the reading system of macroscopical optical instruments. A digitized ruler with absolute code is adopted as the reference of the system, and the ruler is read by the reading system which is composed of optical system, CCD camera and computer. The reading system not only eliminates cumulative error of incremental ruler, but also realizes auto-aiming and auto-reading. The experiments demonstrate that the uncertainty of the reading system is 0.12 μm, which is improved above 5 times than macroscopical reading system.