Abstract
We present here a study of the possibilities of standard bright field microscopy for studying cobalt layers 4 atomic planes thick: this microscopy is often used when qualitative information on many multilayer samples is needed. However, it is important to ascertain what conclusions can be drawn from the bright field images of such small objects without having to resort to a difficult quantitative analysis. We have compared experimental images obtained from ultrathin cobalt films to images calculated with or without defects, including the influence of thickness, defocus and tilt on the images.