ETA Diffractometer (WCR)
ETA X-ray diffractometer GE XRD 3003
With the X-ray diffractometer ETA structure depth gradient analysis (residual stress, texture, microstructure) can be performed in the angle dispersive diffraction mode (monochromatic primary X-rays) within the materials surface nearest region as well as within thin surface layers. Due to the complexity of the instrument it is not possible to operate this instrument without assistance. Booking the ETA diffractometer is only possible after prior consultation with the instrument responsible.
The ETA-diffractometer is a 5-circle diffractometer which was especially developed in a co-operation between the HZB and the company GE Inspection Technologies (formerly SEIFERT) in Ahrensburg. It enables the direct sample rotation around the diffraction vector by means of one single physical axis. Especially due to this additional degree of freedom for the sample orientation the ETA-diffractometer is well-suited for any kind of surface gradient analysis.
The diffractometer is based on the principle of the θ-θ diffractometer operating in the vertical plane. The inclination angle Ψ between the surface normal and ghkl is adjusted by means of an Eulerian cradle segment on a φ1-rotation table, the axis Φ1 of which is perpendicular to the Θ/Θ'-axes. Furthermore, a second φ2-rotation table Φ2 inside the Eulerian cradle segment enables texture as well as full sin2φ analysis. The sample positioning by means of a x-y-z translation table is controlled by a laser and CCD camera system.
As X-ray sources conventional long fine focus Cu- or Co-X-ray tubes are used. The diffracted intensity is recorded with a point detector (scintillation counter). For thin film stress analysis at grazing incidence, a special optical equipment consisting of a polycapillary semi lens in the primary beam and an equatorial soller slit (0.4°) in combination with a flat secondary monochromator (001-LiF) in the diffracted beam is used. For laterally resolved measurements a 100 µm monocapillary is available.
Measurement control and data processing are performed with the program RayfleX® delivered by GE Inspection Technologies, for the residual stress evaluation MATHEMATICA® 4.0 program packages are used which were developed in-house. The texture analysis is performed with the software Labotex®. For the microstructure analysis in-house developed software in MATLAB® can be used.
 Ch. Genzel. Entwicklung eines Mess- und Auswerteverfahrens zur röntgenographischen Analyse des Eigenspannungszustandes im Oberflächenbereich vielkristalliner Werkstoffe. Habilitationsschrift, Humboldt-Universität zu Berlin, 2000.