If a microscope’s resolution is limited by the wavelength of the light it uses, why don’t we use very short wavelength light instead of electrons or other particles for studying very small objects? — SJ, Philadelphia, PA
Ultraviolet light isused in microscopy to achieve higher resolution than can be obtained with visible microscopes. But beyond ultraviolet light comes X-rays and it’s difficult to build imaging optics for X-rays. There are some X-ray microscopes, but they aren’t nearly as common and practical as electron microscopes. The electrons in electron microscopes have very short wavelengths (atomic and subatomic length scales) and yet electron optics are easy to build. So while very short wavelength electromagnetic waves can be made, they’re just not practical for microscopy.