Flexible data collection
Key Features & Benefits
- Photon Counting – Zero Dark Noise
- No Dead Time Between Frames
- Spectroscopic Imaging
- No External Cooling System
- Compact Size
- 55 μm pitch
- 14,400 – 600 Hz depending on bit depth
- 5 – 17 keV Range
- 1, 6, 12 and 24 Bit Counter Modes
- Coherent X-ray Diffraction
- Bunch Synchronised Experiments
- Surface Diffraction
- Phase Contrast Imaging
- Pump and probe experiments
- Powder diffraction
- Multi energy imaging
- High speed real time imaging
- Scanning Transmission Electron Microscope
As the Merlin contains an integrated PC, it requires no external input other than mains power to run. In addition to its own intuitive graphical interface, the system also implements a TCP/IP based remote control function that allows easy integration with a users control systems.
Medipix3 was developed by an international consortium including CERN, DESY, ESRF and Diamond and provides a range of features that are unavailable in other hybrid pixel detectors, including continuous read-write, colour mode, 12 or 24 bit mode selection and all in 55µm pixels. See the datasheet below or the paper for more details.
Brookhaven National Laboratory NSLS-II
A research group lead by Hanfei Yan at Brookhaven National Laboratory’s National Synchrotron Light Source II have achieved spatial resolutions approaching 10 nm implementing the Medipix3 detector MerlinX for ptychography with multimodal scanning hard x-ray imaging. The multimodal imaging is realised by utilising simultaneously absorption-, phase-, and fluorescence-contrast mechanisms.
Their work is an important milestone in hard x-ray scanning microscopy, effectively eliminating the gap between demonstration of optical resolution under ideal experimental conditions and actual imaging resolution for routine scientific measurements.
A 512×512 MerlinX Medipix3 detector with a 55 micrometer pixel size was placed 0.5 metres downstream of the target and used to capture the absorption and phase images. At the same time a Vortex three-element silicon drift detector was used to capture the fluorescence image. By simultaneously utilising absorption-, phase- and fluorescence contrast mechanisms sufficient resolution was acquired to investigate an ionic-electronic conducting ceramic-based membrane material employed in solid oxide fuel cells, as well as membrane separations, revealing the existence of an emergent material phase and quantified the chemical complexity at the nanoscale.
Q. How can Merlin be calibrated?
A. Your Merlin system comes pre-calibrated. Should you wish to add more calibration points to a particular energy, this can be done through the LabView GUI and editing of a calibration text file. Details on how to do this are in the Manual.
Q. Does Charge Summing Mode increase dead time?
A. Yes, very slightly since there is additional logic here.
Q. How long is the cable from the PC to the detector head?
A. Up to 10 meters.
Q. Is it possible to access the FPGA memory directly?
A. No, the system writes to local disk and/or TCP/IP link
Hybrid Pixel Technology
Merlin is a new type of technology in the field of electron microscopy. It is a detector based on a hybrid pixel architecture. The detector assembly consists of a thick, highly resistive semiconductor sensor coupled to a Medipix3 chip. Incoming radiation generates charge in the sensor which diffuses under an applied bias to the CMOS circuitry of the individual pixels (via an array of micro-bump bonds). Each pixel contains >1100 transistors (within the 55 micrometer pitch), enabling on-chip counting of incident electrons and enhanced operation modes such as Charge Summing Mode (more about this later). The counting process consists of analogue comparison of the collected charge to a user selected energy threshold, and subsequent digital counting at 1 MHz if the threshold is exceeded. Thus, since the data readout relating the number of electrons counted by each pixel is digital, the Merlin detector operates free of readout noise. This is a feature unique to hybrid pixel technology and strongly differentiates it from analogue integrating detectors, such as CCD technology. Counting detectors are known to offer highest imaging performance in terms of modulation transfer function (MTF) and detective quantum efficiency (DQE). The Merlin detector has been shown combine ideal TEM performance at the low energies needed to study 2D materials such as graphene for 60keV electrons 1 with 1000’s per second frame rates.
Charge Summing Mode (CSM)
When an electron strikes near the edge of a pixel (illustrated left), the resulting charge may leak into neighbouring pixels, thus reducing the MTF. MERLIN has a unique capability where information is shared between adjoining clusters of four pixels, in what is known at the Charge Summing Mode. When charge spread occurs over the four adjoining pixels, MERLIN recognizes that this information belongs to one event on one pixel rather than up to 4 weaker events on 4 pixels. By reconstructing the event using the diffused charge data, MERLIN increases the resolution and ensures an accurate reading of the event giving improved results quality.
Data Binning in Merlin
MERLIN provides high versatility with a variety of intrinsically fast (due to highly parallelized digital readout) large dynamic range acquisition options, namely: 14,400 fps@1 bit depth, 2,400 fps @ 6 bit depth, 1,200fps @12 bit and 600fps@24 bit depth. These readout modes (unlike the speed-up strategies employed with CCD technology) are unbinned and therefore imply no reduction of pixel resolution or field of view. Moreover, due to the electron counting approach of the detection system as well as the fully digital readout, MERLIN adds zero noise allowing a Signal to Noise Ratio (SNR) as high as a 16.7 million:1.
Dead Time in Merlin
There is no dead time in data collection! The advanced pixel architecture implements two readout counters per pixel and provides a continuous read/write acquisition mode with zero detector dead time (CCD technologies rely on non active detector frame store areas to reduce detector dead time). The various acquisition modes, as well as many other input parameters for the optimisation of the MERLIN system, are easily chosen by a user friendly Graphical Interface as well as remotely controlled via TCP/IP protocol.
Installation of Merlin
The MERLIN system is really “Plug and Play”, with the detector simply connected by one or two cables, depending on the type of installation (static or retractable). The Medipix3 chip has a very low (<1 Watt) power consumption, requiring minimal cooling and no need for connection to microscope water supplies or to pneumatics. The readout electronics are connected to the detector head via a 10 meter cable, thus giving ultimate flexibility. Therefore, MERLIN installation is rapid and designed not to impact on other microscope services.
- Rueff, J.-P., Ablett, J. M., Ceolin, D., Prieur, D., Moreno, T., Baledent, V., Lassalle-Kaiser, B., Rault, J. E., Simon, M. & Shukla, A. (2015). J. Synchrotron Rad. 22, 175-179. “The GALAXIES beamline at the SOLEIL synchrotron: inelastic X-ray scattering and photoelectron spectroscopy in the hard X-ray range.”
- Hanfei Yan, Nathalie Bouet, Juan Zhou, Xiaojing Huang, Evgeny Nazaretski, Weihe Xu, Alex P Cocco, Wilson K S Chiu, Kyle S Brinkman and Yong S Chu. (2018) , , Multimodal hard x-ray imaging with resolution approaching 10 nm for studies in material science.”
- Yong Cai, Sugunya Monsalud, Rudolf Jaffé, Ronald D Jones,Journal of Chromatography A, Volume 876, Issues 1–2, 2000, Pages 147-155, “Gas chromatographic determination of organomercury following aqueous derivatization with sodium tetraethylborate and sodium tetraphenylborate: Comparative study of gas chromatography coupled with atomic fluorescence spectrometry, atomic emission spectrometry and mass spectrometry.”
- Hanfei Yan, Xiaojing Huang, Nathalie Bouet, Juan Zhou, Evgeny Nazaretski, and Yong S. Chu, “Achieving diffraction-limited nanometer-scale X-ray point focus with two crossed multilayer Laue lenses: alignment challenges,” Opt. Express 25, 25234-25242 (2017)
- Hiroshi Daimon. Science Journal of the Physical Society of Japan, 87, 061001 (2018) “Overview of Three-Dimensional Atomic-Resolution Holography and Imaging Techniques: Recent Advances in Local-Structure”.