A dither signal imposition to enhance an image in a scanning electron microscope

In obtaining an image in a scanning microscope many kinds of noise are involved. This noise has a large influence on the image of the sample. In this research, we propose a method for improving image quality by applying dither signal injection. This method involves minimizing the noise that occurs in scan control circuits, which injects both noise and electron beams emitted in the course of A/D (analog to digital). The collected secondary electrons are multiplied through a photo multiplier tube (PMP) and then are converted to digital through an A/D converter. At this point, distortion occurs during the A/D process, which appears as white noise. We propose to minimize this white noise by using dither.