A eucentric goniometer head sliding on an extended removable arc modified for use in cryocrystallography

Efficient crystal handling at cryotemperatures requires flexible tools. A standard goniometer head has been modified such that it retains eucentricity and allows any position between the coaxial and vertical orientations relative to a horizontal spindle axis, corresponding to the positions of data collection and crystal transfer, respectively. This is accomplished by a large arc on which slides the upper portion of the goniometer head containing all three translational and one rotational degree of freedom. The arc can be removed when the head is coaxial with the spindle. The head is designed to accept commercially available cryotools. In addition, a heat-shield assembly can be installed to prevent the formation of ice.