X ray diffraction techniques are used to determine the crystallographic structure of matter. This technique is used in a wide variety of research fields like biology, pharmacology, medicine, solid state physics, and material chemistry. The (purely) mechanical 3-axis goniometers that are currently used have reached their limit of precision, namely the intersection point of the 3 rotation axes can be determined with a precision of at least 3 m. This precision is not accurate enough to maintain the center of a micro-crystal (studied for example by biologists) with respect to that intersection point. Besides, since these instruments cannot account for the effect of gravity, the mass of the sample is limited to about 500 g. We propose to develop a high precision 3 axis goniometer with a precision that should meet the actual requirements of researchers. The originalities of the concept are - the use of high-precision capacitive sensors in order to measure the deformations of the rotation axes caused by gravity; this will allow the electronic control of each axis relative position, and hence a much better precision of the instrument. - the desolidarisation of the fixed frame, which supports the sensors, from the constrained frame which supports the mechanics and the sample to be studied. This new concept should allow - to identify the intersection point of the three rotation axes with a precision less than 1 m. - to study samples with no mass limitation, and especially to use high pressure cells. The realisation of this goniometer will require the development of highly precise capacitive sensors and associated electronics, as well as the fabrication of high precision mechanical assemblies. The main objective of the project is to realise a prototype which will be tested in a synchrotron. The next stage will be the pro(luction in series of the goniometer and its commercialisation.
Funding SchemeEAW - Exploratory awards