LATTICEPATCH – an interactive graphics program to design data measurement strategies for area detectors

LATTICEPATCH is an interactive graphics program used to evaluate strategies for measuring X-ray diffraction data with area detectors. It is written in C and runs on the Silicon Graphics IRIS Series 3000 computers. It displays, at designated resolution, a sphere in reciprocal space and indicates the area(s) on its surface that both satisfy the Bragg condition and are projected onto the detector surface(s) during φ and ω rotations of the goniostat. The user can determine an efficient strategy for obtaining a unique set of data by changing interactively the goniostat settings. The orientation of the crystal may be changed to accommodate the use of several crystals. Symmetry operations may be invoked to produce equivalent scans and the reciprocal-space representation may be rotated about the x, y and z axes of the screen. The relevant calculations are discussed, the program is described and the development of strategies in several cases using LATTICEPATCH is examined.