3-D electron microscopy and incomplete angular coverage: a restoration scheme based on projections onto convex sets

The author treats the problem of calculating the 3-D structure of a biological specimen from its images obtained in a transmission electron microscope. In general, this process is accomplished by tilting the specimen inside the microscope, collecting the tilted images, and using these data as input to a 3-D reconstruction algorithm. However there is an unavoidable limit for the maximum tilt angle that can be achieved. Methods to recover the missing information are thus fundamentally needed. The author presents an approach based on projections onto convex sets (POCS) as it has been applied to a subviral particle, and comments on the obtained results