Description

The diffractometer unit is the core of HEiDi. It performs three central tasks:

• Positioning and orienting of the sample in the monochromatized primary beam,
• mounting of special sample environments, e.g. for temperature dependend measurements,
• positioning of the detector to collect the radiation diffracted by the sample.

Hardware

Mechanic
• Large acentric Euler cradle to mount the sample and its environments (400 mm diameter), turn angles χ and φ.
• goniometer to mount the Euler cradle, turn angle ω
• gonimeter to mount the detector holder, turn angle 2θ,
• diffractometer base with integrated guidance rail to the biological shielding on three air cushions for positioning.
Electric
• Step motors on all four axes,
• microstepping capable driver for all axes to supress resonances at slow movements,
• absolute encoders with a resolution of 12bit/degree (equivalent to about 0.00025°).

Control

• S7 controller with integrated cpu and Profibus interface,
• internal position control and correction via absolute encoders
• synchronous movement of all four axes is possible. This allows continous movements during the intensity detection (continous scan).