We now need to try to answer a series of questions that should arise.

- (a) What happens in the general case if we ignore the phase and try to recombine with just the intensities?
- (b) How can we by-pass or otherwise solve the problem of the phases that cannot be measured?
- (c) How can the statements made in section 2 about focusing be reconciled with the solutions of the phase problem which we have just listed and described under (b)?
- (d) What determines the accuracy of reproduction of the image?
- (e) What complications are introduced by the fact that crystals are three dimensional?

**Copyright © 1997 International Union of Crystallography**