OPTIMUS TKD Detector Head

Bruker’s high performance eFlash EBSD detector series can now be configured with the OPTIMUS^™ TKD detector head which was specifically designed for best sample-detector geometry for on-axis Transmission Kikuchi Diffraction analysis (TKD) in SEM. The detector head not only acquires Kikuchi patterns with unmatched sensitivity, but even provides access to SAED (Selected Area Electron Diffraction) like patterns.

Orientation mapping with at least 2 nm spatial resolution

The horizontal phosphor screen's position beneath a sample has two major advantages compared to the vertical standard setup:

one order of magnitude stronger signal
lowest possible gnomonic projection distortions

The significantly stronger signal allows to acquire orientation maps with small apertures thus enabling improved spatial resolution. Results on various materials indicate an effective spatial resolution of 2 nm or better when using a high-end FE-SEM. Working at low acceleration voltages down to 5 kV is also possible. This helps to reduce the mean free path and thus to increase the yield of Kikuchi diffraction signal. This is extremely useful when analyzing thin and “lightweight” samples. Distortions caused by gnomonic projection are a common issue in EBSD and especially affect TKD analysis when using the vertical phosphor screen.

However, OPTIMUS^™ TKD allows to exactly match the phosphor screen's center with the pattern center thus enabling ideal geometric conditions, better even than what standard EBSD geometry offers. The resulting Kikuchi patterns have minimum distortions which significantly improve band detection and subsequent indexing accuracy.

OPTIMUS™ detector head in working position beneath the electron transparent sample.

ARGUS^™ FSE imaging system

OPTIMUS^™ TKD is equipped with the ARGUS^™ imaging system that enables brilliant Dark and Bright Field like imaging with details down to nanometer scale, practically transforming your SEM into a "low-kV TEM". ARGUS^™ can be used to display individual dislocations and networks of dislocation walls in deformed materials. The Dark Field like images show 3D information on boundary plane position and inclination.

Ease of use

Every existing eFlash detector can be fitted with the OPTIMUS^™ TKD detector head. The exchange can be easily done in less than 10-15 minutes by a trained user. This allows an easy and fast switch between EBSD and TKD mode whenever needed. OPTIMUS^™ TKD features Bruker's advanced collision protection system: in the unlikely event of collision the detector immediately retracts at a speed of 10 mm/s which significantly reduces the risks of any damage. The OPTIMUS^™ TKD detector head seamlessly works with Bruker’s TKD Professional Toolkit for SEM including TKD sample holder, the XFlash^® EDS detector series for simultaneous TKD/EDS measurements and the ESPRIT 2 analytical software suite.

Raw orientation map without data cleaning shows annealing twin domains in fcc crystals (A). The map was acquired at a speed of 140 fps from a Gibeon iron meteorite using 1 nA probe current and 30 kV EHT.

Detail of raw orientation map without data cleaning. It shows annealing twin domains in fcc crystals just 6 to 9 nm wide.

OPTIMUS™ TKD detector with ARGUS™ direct electron detection system for brilliant dark and bright field imaging.

Color coded dark field image acquired from a heavily deformed pure Al sample. The insert shows individual dislocations.

Color coded dark field image acquired from a heavily deformed (ARB) Al alloy sample. The highlighted area shows 3D details. The position and inclination of the boundary plane between grains is visible through the sample thickness.

Pattern quality map and corresponding raw orientation map acquired at 100 fps with a 4 nm step size from a FIB prepared Au sample using ~0.6 nA probe current and 28 kV EHT. The effective spatial resolution is at least 3 nm.

Color coded dark field image acquired from a FIB prepared SiC sample. The image depicts a heavily twinned microstructure with some twins being less than 10 nm wide.

Bright field (left) and corresponding dark field image (right) acquired simultaneously from heavily deformed (ARB) Al alloy sample showing the presence of precipitates at the grain boundaries.