TOMCAT Endstations

The S-TOMCAT endstation 1 (ES1) is designed to accommodate a wide range of imaging experiments – from low- to high- spatial and temporal resolutions, standard absorption-contrast and single-distance propagation-based phase contrast tomographic microscopy. The endstation has been kept simple to promote ease of use. It is suited for small to large samples and is flexible to host a variety of user-specific sample environments and sample setups. It is equipped with an air-bearing Aerotech rotation stage (ABRT200) with a maximum rotation speed of 3600 degrees/s, enabling up to 20 Hz time-resolved tomographic experiments. An electrical slip ring provides easy connections for electric signals to the rotating sample or rig for up to 48 lines (1 A, 230V max). The rotation stage features a central aperture of 14 mm diameter to facilitate custom fluid connections to bespoke sample environments. 

The high-precision, rapid sample positioning axes are ideal to perform vertically stacked, or fully mosaic acquisitions of multiple overlapping scans to expand the measured sample volume. Fast and efficient detector positioning (possibly in combination with end station 2) allow for comprehensive multiscale tomography studies over a wide range of resolutions. 

Source distance, beam size, FOVs, etc

The endstation sits on a horizontal rail and can be positioned between ~19 m to 27 m from the source. The beam size at 25 mm from the source is 50 mm (horizontally) x 3-5 mm (vertically, depending on the energy mode). Various microscopes and cameras from the TOMCAT pool of detectors can be combined depending on the desired magnification, spatial resolution, field of view, X-ray energy to be used and the required acquisition speed. The maximum field of view (h x v) ranges from 0.4 mm x 0.3 mm to 22 mm x 3-5 mm and corresponding effective pixel sizes are 0.16 μm to 11 μm, respectively. Up to two or even three detector/microscope setups can be mounted in parallel, if a quick configuration switch is necessary.

Sample-to-detector distances

The maximum sample-scintillator distance is ~600 mm. This distance should be sufficient for most experiments, thanks to the high coherence of the beam and the high spatial resolution aimed at this endstation. The minimum achievable distance is limited by the sample dimensions, sample environment, and microscope geometry. 

Horizontal and vertical sample positioning

The vertical (Y-axis) travel range of the sample manipulator is ±37 mm and enables continuous scanning of ~70 mm tall samples, if they are optimally mounted with respect to the beam height. The horizontal cross (XX/ZZ) linear stages on top of the rotary stage has a range of ±25 mm, enabling motorized alignment in the beam and mosaic scanning of relatively large samples. The XX/ZZ stages can only operate up to 450 degrees/ sec (tomography experiments up to 2.3 Hz). If you have any concerns or are not sure whether your sample is compatible with this endstation, please contact the beamline staff. 

If feasible, your samples should be mounted on pins, which fit our 3.15 mm sample holder. For precise specifications, please consult: Sample holder specifications. 

If you are instead planning to bring your own sample holders, please check the information regarding the sample manipulator base plate for a seamless integration.

The second endstation (ES2) in the first experimental hutch (EH1) of I-TOMCAT is dedicated to high-throughput high spatial resolution tomographic microscopy, exploiting absorption contrast, simple edge-enhancement or single distance propagation-based phase contrast. Routinely, single, vertically stacked or mosaic scans can be performed at this endstation, as well as simple time-resolved experiments. 

The design of the endstation has been optimized with high image quality in mind. In this respect, stability is key. The sample manipulator and detector are therefore positioned on a granite base. The endstation has been kept simple to promote ease of use. It is equipped with an air-bearing Aerotech rotation stage (ABRX150) with a maximum rotation speed of up to 1500°/s, enabling a few Hz tomographic experiments.  

The endstation is suited for small- to medium-sized light samples, while the capacity to host sample environments is limited. For heavier and larger samples as well as for complex sample environments, explore the capabilities of the other endstations at I-TOMCAT (especially ES3) and S-TOMCAT. 

Distance from the source, beam size, FOVs, etc

The endstation is located at 33 m from the source. The maximum beam size at the sample position and therefore field of view (FOV) is ca. 1.5 x 1.5 mm². TOMCAT has a pool of microscopes and cameras, shared across the different endstations, which can be combined in different ways depending on the experiment, to achieve a wide range of FOVs, effective pixel sizes and temporal resolutions. Table 1 provides a summary of the most relevant combinations for this endstation, covering an effective pixel size from 0.17 to 1.1 um and a FOV from 0.75 x 0.4 to 1.5 x 1.5 mm². Up to 2 combinations can be mounted in parallel, if a quick configuration switch is necessary.

Table 1 – Effective pixel sizes and field of views (FOV) for microscope/camera combinations relevant for I-TOMCAT ES2. For more information on the single microscopes and cameras, please consult the TOMCAT Detectors page. 

Sample-to-detector distances

The maximum sample-scintillator distance is approximately 300 mm. This distance should be sufficient for most experiments, thanks to the high coherence of the beam and the high spatial resolution aimed at this endstation. If a single head microscope is used, samples can be positioned within a few mms from the scintillator screen. With the double head microscope (Microscope 6) restrictions apply for tall samples. 

Horizontal and vertical sample positions

The Y-axis travel range of the sample manipulator enables continuous scanning of ca. 70 mm tall samples, if they are optimally mounted with respect to the beam height. The maximum distance between the sample manipulator base plate and the region of interest should not exceed 110 mm. The horizontal cross linear stage on top of the rotary stage has a range of ±12 mm, enabling motorized alignment in the beam and mosaic scanning of relatively large samples. If you have any concerns or are not sure whether your sample is compatible with this endstation, please contact the beamline staff. 

If feasible, your samples should be mounted on pins, which fit our 3.15 mm sample holder. For precise specifications, please consult: Sample holder specifications  

If you are instead planning to bring your own sample holders, please check the information regarding the sample manipulator base plate for a seamless integration. 

Advanced imaging techniques

X-ray fluorescence (XRF) full-field radiography and tomography are in development and will be offered at this endstation in the near-to-mid future to gain chemical information on the investigated samples. The setup foresees an energy resolved 2D detector (e.g. Mönch) in combination with a pinhole in a camera obscura configuration. The spatial resolution will be around 5-25 um. Single projections will be acquired in a matter of seconds, full tomograms in a few minutes. If this technique is of interest for you, please contact the beamline staff for further information. Pilot experiments are possible. 

For high throughput experiments, studying many samples of the same kind, an automatic sample exchanger based on a robotic arm is foreseen, but not yet available.