Hacker News Reader

At that resolution, is there an application for which you think your microscope is better than an optical one?

Not that it really matters, I'm impressed even if there isn't such an application.

The "f number" of the SEM is about 200, so it's depth of field is much larger than an optical microscope or camera. Also, the SEM signal of bright and dark areas is made of electrons, which can travel in curved paths and around corners. This gives the SEM image an appearance that is distinct from light images, and is helpful when viewing 3d objects for ease of feature recognition as well as aesthetic quality. Even at low magnification, SEM is often more useful. Thanks!

An SEM with a backscatter detector can be used to image changes in material. Backscatter is proportional to atomic number. A common sample to measure is the solder diffusion depth into the copper on a pcb. The first time I imaged such a sample was mind opening in the sense of understanding why you can't remove all the solder from copper, some of the solder is in the copper.

Reply on news.ycombinator.com