Making a microscope without a lens

URL

http://arstechnica.com/science/news/2011/03/making-a-microscope-without-a-lens.ars

Description

To create a high resolution image, you want the largest possible diameter combined with the shortest possible focal length. The result is a lens that collects light from a large cone of angles, allowing us to construct an image with more closely spaced features. Unfortunately, there is an upper limit to the combinations of lens diameter and focal length that limits resolution to about half the wavelength of the light used to image—so, for a visible light microscope with the best lenses and a few other tricks, the best resolution is about 200nm. This limit is called the diffraction limit. Superresolution refers to techniques that allow one to beat this limit.