what is a stereoscopic microscope used for?

Answer 1

Stereoscopic microscopes have two eyepieces- like stereoes have two speakers. They are also called binocular or dissecting scopes. Because you have two eyepieces, you can see in 3D; there is depth to the image. Monocular microscopes with one eyepiece show a flat 2D image. If you want to see 3D images, use a binocular microscope.

Answer 2

You can use one to look at a solid object's surface, not just a slide. For example, an insect or tiny fossil tooth.