The MerlinX photon counting detector system utilises a Medipix3 ASIC. MerlinX is packing a lot in for its size. With a vast range of applications, MerlinX is a high performance X-Ray imaging detector.


Overview of the MerlinX

With a vast range of applications, Merlin is a high performance X-Ray imaging detector that requires no additional cooling system, and being around the size of a mobile phone, is easily installed into small spaces. The system is supplied with a LabView GUI to get you up and running quickly while TANGO and EPICS drivers have been written to allow you to integrate it into your system.

MerlinX is fast. Allocated to each of its 55µm pixels are 2 x 12 bit counters which allows continuous read/write with no dead time between frames. MerlinX is available with either as MerlinX – a single Medipix3 chip (256×256 pixels) or Merlin4X – a quad (512×512 pixels) system and has excellent sensitivity in the 5-17 keV range. The detector is installed at beamlines and laboratories globally, including several at NSLS-II, APS, DLS, PAL, SOLEIL, DLS, BSRF, and Spring-8.


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  • 55  μm pitch
  • 21,000 – 900 Hz depending on bit depth
  • 5 – 17 keV Range
  • 1, 6, 12 and 24 Bit Counter Modes
  • Continuous data collection
Hanfei_2018_50nm_au_particles_1x1um2FOV (1)

MerlinX data

Reconstructed phase image using the Medipix3 detector MerlinX at Brookhaven National Laboratory’s NSLS-II. of a Au nanoparticle array. Particle size is 50 nm and field of view 1 x 1 um^2.

Screenshot 2021-12-10 at 11.35.33

The MerlinX in Action

The video shows a Merlin4X (512 x 512 pixels, 28.2 x 28.2 mm) recording a rotating chopper at a frame rate of 1KHz with no deadtime

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Applications for the MerlinX

Quantum Detectors systems are designed with you in mind. We want to help you achieve results, here are some of the applications this system is capable of.



Ptychography is a subset of Coherent Diffractive Imaging (CDI) which uses a coherent energy source (in our case, electrons or X-rays) to illuminate a sample and retrieve the phase information on the sample from phase-retrieval analysis of the far-field diffraction pattern.

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Features of the MerlinX

Rapid Gapless Readout and high dynamic range

Within each pixel are two counters, which can be used simultaneously to give gapless readout – whilst one counter reads, the other reads out. This unique approach is of particular importance for beam sensitive samples – there is no gap in time for readout so every part of the exposure to the sample is being read and recorded. This feature and the speed of the detector can be used to record gapless multiframe films of dynamic effects and it can be also used to collect diffraction sample tilt series by continuous rotation of the goniometer, without loss of any photon data to the read-out. Due to the photon counting approach of the detection system as well as the fully digital readout, MerlinX adds zero noise allowing a Signal to Noise Ratio (SNR) within a single frame as high as 16.7 million to zero.

Flexibility of experimental approach

MerlinX provides high versatility with a variety of intrinsically fast – due to highly parallelised digital readout – large dynamic range acquisition options, namely: 18,000 fps@1 bit depth, 3,200 fps @ 6 bit depth, 1,600 fps @12 bit and 900 fps@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.

Effectively noise free

Each of MerlinX’s pixels contains >1100 transistors within the 55 micrometer pitch, enabling intelligent processes to occur on chip. Each incoming photon is evaluated, and if it is above a user specified threshold energy level, the signal is counted. If it is not, then it reads as zero. This feature allows for noise-free data collection. This is unique to hybrid pixel technology and strongly differentiates it from analogue integrating detectors, such as indirect CCD technology or CMOS.

Charge Summing Mode (CSM)

“Charge Summing Mode” (CSM) is a useful mode designed to allow for a better detection of particles striking close to the pixels’ edge and to alter charge spreading. For example, if the threshold is set to 70% of the beam energy, a photon striking the edge of the pixel may not be counted in a standard, single pixel mode. It will not deposit enough energy to trigger the count in any pixel. If CSM mode is active, the detector electronics will compare the charge in the neighbouring pixels and assign it to the pixel with the largest deposited charge. The sum of the deposited energies will be compared against the threshold. This maximises the DQE response of the detector.


MerlinX comes with everything you need to start collecting data. The MerlinX readout electronics are based on a National Instruments PXI FPGA system with custom control electronics. This is a robust, extensible and well supported platform with a long product lifetime. It integrates a separate high performance industrial grade PC and FPGA card. The detector head is connected by a high density cable link that can be up to 10m long allowing a significant degree of flexibility in the mounting of the system. MerlinX 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 other control systems such as TANGO and EPICS.

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Chris Hearn

Chris Hearn

Technical Sales Engineer

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