3D reconstruction of 2D crystals from projections in real space

A new algorithm for 3D reconstruction of two-dimensional crystals from projections is presented, and applied to biological macromolecules imaged using electron microscopy. Its main departure from the traditional approach is that it works in real space, rather than in Fourier space, and is iterative. This approach has the advantage of making it convenient to introduce additional constraints (such as the support of the function to be reconstructed, which may be known from alternative measurements) and has the potential of more accurately modeling the electron microscope image formation process.