Does the Scanning Electron Microscope Have an Objective Lens?

Abstract

Abstract No, Virginia, there is no objective lens in the Scanning Electron Microscope. There is much confusion about the lenses in a scanning electron microscope (SEM). All of the lenses in a SEM are condenser lenses. The fact that some scanning electron microscope manufacturers have labelled the controls for the final condenser “objective lens” is misleading and this may have contributed to the confusion. To get some perspective on this matter, observe your compound light microscope. Starting with the light source, the first lens encountered is the condenser lens (the lens that handles the light before it interacts with the specimen). Next the light interacts with the specimen on a microscope slide. Then the light enters the objective lens (the first lens the light enters after interacting with the specimen) and finally the light travels through the ocular lens and then it enters your eye.