Bionic optimization of the cast iron structure
All BESSY II undulator supports are cast iron structures. Regarding the functional surfaces the pieces are optimized by minimizing simultaneously the stress and the mass of material. The complexity of the objects can be much higher as compared to a welded support frame. The latest undulator design (5m APPLE II) is based on a single piece of cast iron which simplifies machining and assembling of the complete support and drive system. Efficient production procedures are possible employing wooden forms which can be used for many casts
Gap measurement system for high reproducibility
An absolute linear encoder is used as gap measurement system. It is located right above the electron beam excluding any measurement error due to a magnet girder roll during gap or shift movement (Abbe comparator error).