Determination of the Orientation of a Randomly Placed Crystal from a Single Oscillation Photograph

A technique is described to determine the orientation of a crystal from a single oscillation photograph. This procedure is particularly useful for crystals that are so radiation sensitive that stills can be taken neither before nor after the single oscillation data exposure. It also ensures optimal use of synchrotron radiation, as all available time is then used to collect data photographs, while no time is wasted in obtaining setting photographs or in correcting the crystal orientation. The method is based on correlating the unique set of calculated normals to reciprocal-lattice planes with the observed zone axes on the oscillation film. Although the method was developed to allow processing of films taken of radiation-sensitive Mengo virus crystals, it can equally well be used to analyze any film of a crystal with unknown orientation.