Study of resolution improvement of dimension measurement by linear CCD image sensor

摘要

In this paper, the principle using linear CCD to measure geometrical dimension is introduced, and the edge distribution of the light intensity under the practical noncoherent illumination and the diffraction light on the straight flange is theoretically analyzed. It is suggested that the discrete image signal output of CCD is smoothed and the zero-passing moment of the second derivative of the smoothed signal is detected to obtain the point of inflection on the light intensity distribution. An experimental installation has been designed. it is stated that the experiment can carry the resolution in one-fourth of a pixel size, for example, the resolution of a TCD132D image sensor with the pixel distance of 14$mu@m can carry about 3.6$mu@m.