Full-field imaging at a fourth-generation synchrotron source is defined by a relatively small but very bright x-ray beam, as detailed in the publication linked below. Currently we are limited to the natural x-ray beam, although we are looking into options for expanding it. In terms of dynamics, in turn, our rotation stage and CMOS camera limit tomoscopy to 20 Hz or slower; for faster dynamics radioscopy or XMPI may be suitable. Technical details of the setup are listed below.
Publication
Detection system
ForMAX is equipped with a high-resolution full-field detection system consisting of two main components, an optical microscope and a sCMOS camera (detector). The x-ray image formed by the transmission (and refraction) of the x-ray beam through the sample is converted by a scintillator into visible light. This visible light image is then magnified by the optical microscope. The magnified image is recorded digitally by a high sensitivity visible light sCMOS camera.
Optical microscope
The ForMAX endstation features a high-resolution white-beam optical microscope from Optique Peter, with a triple objective lens configuration allowing the selection of three different magnifications by motorised switching of the objective heads. We typically employ a 10x magnification objective, but the microscope can also accommodate 2X, 5X, 7.5X, and 20X objectives, as listed in the table below together with details of field-of-view and effective pixel sizes (calculated for the Andor Zyla 5.5 camera with a pixel size of 6.5 µm). The measured resolution is also provided as guidance.
| Magnification | Field-of-view (h x v, mm2) | Pixel size (µm2) | Resolution (µm2) |
| 2X * | 8.3 x 7.0 | 3.25 x 3.25 | |
| 5X * | 3.3 x 2.8 | 1.30 x 1.30 | 2.6 x 2.6 |
| 7.5X * | 2.2 x 1.9 | 0.87 x 0.87 | |
| 10X | 1.7 x 1.4 | 0.65 x 0.65 | 1.3 x 1.3 |
| 20X | 0.8 x 0.7 | 0.33 x 0.33 | 1.0 x 1.0 |
* Note: The field-of-view given by these objective magnifications will be achieved with the eventual installation of secondary beam-expanding optics.
sCMOS cameras
Three different sCMOS cameras are available for use at ForMAX; the Andor Zyla 5.5, the Hamamatsu ORCA Lightning, and the Photron FASTCAM Nova S16, as detailed in the table below. All cameras are coupled to the optical microscope via a dual camera port configuration, allowing selection of the camera by motorised switching of the camera port. The choice of camera depends principally on the requirements of the experiment in terms of the desired field-of-view and the achievable pixel size, in relation to the objective magnification, and acquisition speed. In practice, the Andor Zyla and the Photron FASTCAM are in active use.
| Camera | Andor Zyla 5.5 | Hamamatsu ORCA Lightning | Photron FASTCAM Nova S16 |
| Number of pixels | 5.5M | 12M | 1M |
| Sensor size (h x v) | 2560 x 2160 pixels | 4608 x 2592 pixels | 1024 x 1024 pixels |
| Pixel size (h x v) | 6.5 x 6.5 µm2 | 5.5 x 5.5 µm2 | 20 x 20 µm2 |
| Maximum frame rate (full frame) | 40 Hz @ 16-bit; 100 Hz @ 12-bit | 30 Hz @ 16-bit; 121 Hz @ 12-bit | 16 kHz @ 12-bit |
Sample manipulation
Microtomographic imaging
ForMAX is equipped with a modular stack of sample stages from LAB Motion Systems (from bottom to top):
- Linear stage, from Föhrenbach (375 mm full travel range)
- Vertical stage, model 5103.A20-40 from Huber (+/- 20 mm translation range)
- Rotary union, allowing passage of fluids (gases, liquids, dispersions) through the rotary axes to the sample environment on top
- Air bearing rotary stage, model RT150ST (maximum rotation speed 725 rpm; maximum load capacity 43 kg)
- 2-axis horizontal sample alignment stage (+/- 6 mm translation range for each axis; maximum load capacity 10 kg)
The stack of stages also encompass an electrical slip ring, that passes power and electrical control signals from underneath to the top of the rotary stage. Underneath the rotation stage users can connect to the electrical feedthrough using a female DSUB-15 HD connector and on top using a male Lemo FPG.1B.316 or FGG.1B.316 type connector, with the following correspondence between pins (DSUB – Lemo): 1-1, 2-11, 3-10, 4-9, 5-8, 6-7, 7-6, 8-5, 9-4, 10-3, 11-2, 12-12, 13-16, 14-15, 15-14.
X-ray multi projection imaging
For XMPI we also offer a modular 3-axis stack from Huber (from bottom to top):
- 2-axis horizontal stage, model 5102.25 (+/- 25 mm translation range for each axis)
- vertical stage, model 5103.A20-40 (+/- 20 mm translation range)
- optical breadboard on top (M6 25×25 mm centred hole pattern) to facilitate mounting of sample holders or environments