The Microscope

The Compound Microscope Compound microscopes use two or more lenses to magnify objects. Compound light microscopes, use compound lenses and light to magnify objects. The lenses bend or refract the light, which makes the object beneath them appear closer.

The principle of the compound microscope The principle of the compound microscope. The passage of light through two lenses forms the virtual image of the object seen by the eye.

The Scanning Electron Microscope The scanning electron microscope (SEM) bombards a specimen with a beam of electrons instead of light to produce a highly magnified image from 100x to 100,0000x. Its depth of focus is some 300 times better than optical systems at similar magnification. The bombardment of the specimen’s surface with electrons normally produces X-ray emissions that can be used to characterize elements present in the material under investigation.

A schematic diagram of a scanning electron microscope displaying the image of a gunshot residue particle. Simultaneously, an X-ray analyzer detects and displays X-ray emissions from the elements lead (Pb), antimony (Sb), and barium (Ba) present in the particle.