Synchrotron is a significantly powerful X-ray source. Here, the X-rays are produced by highly accelerated electrons, emitting energy at X-ray wavelength when changing directions. These X-ray beams are steered to an experimental end-station with a beamline. In the end-station, they interact with matter, which helps in studying the properties of different materials. X-ray wavelength is much shorter compared to visible light, which makes it possible to probe much smaller structures (in nanometer range) compared to traditional microscopes.
Depending on their energies, X-rays have high penetration capabilities. Therefore, they are quite often used in imaging. The beams are highly focused, which makes sample positioning a major issue. Therefore, detection, triggering, and feedback of the sample position should be well sustained and documented.
The open source interface, BiSS-C is based on the RS422 protocol supporting signal transmission of up to 10 MHz . The option for processing external trigger signals, also supported up to 10 MHz, allows the synchronization for a number of devices. Considering the demand for synchronous data communication, attocube provides an IDS3010 with the BiSS-C interface that suits the standards of the Diamond Light Source and Omron/Delta Tau.
Error motions and vibration propagation are vital information for the motion accuracy in high precision systems for moving objects in nanometer ranges. Due to this, synchrotron facilities continue to upgrade and develop different components to keep pace with the most recent available technology. Recently, the beamline I08 upgraded the endstation using attocube interferometers IDS3010 with BiSS-C interface. An experimental setup at the Diamond Light Source is synchronously triggering and tracking the movement of eight different linear axes. The Delta Tau “GeoBrick” controller controls these eight axes. The Delta Tau “GeoBrick” controller ensures the accurate time stamped data from all eight axes, that is, the three IDS3010 devices.
Figure 1 shows a simplified version of the set up. It consists of three motion modules: a manual positioned at the bottom, on top of it a stepper motor for more coarse adjustments, and finally on top of that a piezo-based positioner for fine motions. All three modules can move in X-, Y-, and Z-direction. The complete setup consists of nine linear movements and is tracked by 8-axes consisting of M12/C1.6 high vacuum compatible sensor heads. Every motion needs to be tracked since the sample’s position is relevant for each movement of the three modules. Two kinds of error motions (parasitic movements) are relevant for the sample’s position: vibrations caused by moving the positioner that spread to connecting positioners and the sample, as well as uneven motions caused by non-parallel mountings between the positioners.
Figure 1. Rough sketch of the setup. The eight sensor heads M12/C1.6 are shown monitoring the 3 modules, each module consist of 3-dimentional X, Y, and Z movements. The complete setup is in high vacuum.
Figure 2 shows a measurement example, which only involves the X, Y, and Z piezo-based positioners in the upper module. The two parasitic movements are shown while moving the fine piezo positioner in the X-direction using 5 nm step sizes. The red line (X-axis) shows the positioner moving in one direction, after 10 steps, the positioner is moving back with one 50 nm step. The blue line (the Y-axis) shows the error motions of the fine positioner orthogonal to the motion of the positioner in the horizontal level.
The noised oscillations are caused by the vibration propagation emerging from the positioner’s motions. This line shows a linear offset of 10 nm for every step. This offset originates from the not perfect parallel mounting between the X- and Y- positioners. Using the information for the other axes, this non orthogonal mount can be compensated. The green line (Z-axis) shows the vertical movements of the fine positioner. Only the last step of 50 nm shows a considerable change of the vertical position, probably caused by a rapid vibration.
Figure 2. The blue curve shows the water surface and sensor head movements and the red curve represents the displacements measured on the side of the mirror after hitting the optical table with a hammer.
This synchronous motion capturing and data acquisition of different measurement axes was realized by the BiSS-C interface in addition to the picometer resolution provided by the IDS3010. This real-time interface facilitates the simultaneous triggering of multiple measurement axes. In this example, eight axes of three IDS devices were triggered for synchronous data acquisition. With the BiSS-C interface connected with the Master Control on the Delta Tau, one could read the eight incremental encoders from the positioners as well as the eight interferometer axes. It also gives the absolute positioners without the need to cross any reference axis.
 Official BiSS-C website: http://www.biss-interface.com/
 IDS3010 interfaces description http://attocube.com/attosensorics/ids-sensors/ids3010/
This information has been sourced, reviewed and adapted from materials provided by Attocube Systems AG.
For more information on this source, please visit Attocube Systems AG.