29 January 2015

Zero-lens microscopy

Visible light is good for seeing details down to a fraction of a micron. Below this limit, one uses X-rays, with a wavelength of the order of one Ångström. The problem is that there are no high-quality lenses for X-rays, and so, instead of direct images, one has to settle for scattering or diffraction patterns, much more difficult to interpret (but sometimes more useful).

If the magnifying glass is a one-lens optical instrument and the microscope is (schematically) a two-lens device, then an X-ray scattering setup does zero-lens microscopy!

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