Full-field imaging at a fourth-generation synchrotron source is governed by a relatively small but very bright x-ray beam, as detailed in the publication linked below. Our approach is to provide fast imaging using the natural x-ray beam, with the eventual option to readily expand the x-ray beam using refractive optics in order to obtain a larger field of view when needed. Details of the setup for full-field microtomography in terms of the specific equipment are listed below.
Publication
Detection system
ForMAX is equipped with a high-resolution full-field microtomography 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. The microscope can accommodate 2X, 5X, 7.5X, 10X and 20X magnification objectives, as listed in the table below together with details of field-of-view and effective pixel sizes. These are 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 installation of refractive lenses for producing a larger beam at the sample position.
sCMOS cameras
Two different sCMOS cameras are available for use at ForMAX, the Andor Zyla 5.5 and the Hamamatsu ORCA Lightning. We are also commissioning a faster sCMOS camera, the Photron FASTCAM Nova S16. 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. The principal specifications of each camera are as follows:
| 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) | 75 Hz @ 16-bit; 100 Hz @ 12-bit | 30 Hz @ 16-bit; 121 Hz @ 12-bit | 16 kHz @ 12-bit |
Sample manipulation
ForMAX is equipped with a modular configuration of sample stages from LAB Motion Systems, consisting of the following specific stages from top to bottom in the stack:
- 2-axis horizontal (X–Z) sample alignment stage (+/- 6 mm translation range for each axis; maximum load capacity 10 kg)
- Air bearing rotary stage, model RT150ST (maximum rotation speed 725 rpm; maximum load capacity 43 kg)
- Rotary union
- Vertical (Y) stage, model 5103.A20-40 from Huber (+/- 20 mm translation range)
- Linear (Z) stage, from Föhrenbach (375 mm full travel range)
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 a one-to-one correspondence between pins 1-15 of each connector.
Fluid slip ring
The rotary union module of the sample stage configuration allows passage of fluids (gases, liquids, dispersions) through the rotary axes to the sample environment on top.