- Photon Counting Eliminating Dark Noise
- Zero Dead Time Between Franmes
- Spectroscopic Imaging
- No External Cooling System
- Compact Size
- 55 μm
- 1200 Frames Per Second
- 1 μs Exposure Time
- 5 – 17 keV Range
- 12 and 24 Bit Counter Modes
Merlin is capable of taking 1200 frames per second in burst mode and 100 frames per second in continuous mode. Allocated to each of its 55µm pixels are 2 x 12 bit counters which allows continuous read/write with no dead time between frames. With 2 threshold levels per pixel, up to 8 thresholds can be set by creating a super-pixel (combining 4 pixels together). Stepping through the resulting threshold images allows easy interpretation of the intensity of X-Ray absorption at user defined energy levels. Merlin is available with either a Single medipix3 chip (256×256) or Quad (512×512) system and has excellent sensitivity in the 5-17 KeV range. The detector is already installed on 5 beamlines at Diamond Light Source and has had successful trials at other synchrotrons.
Coherent X-ray Diffraction
Bunch Synchronised Experiments
Phase Contrast Imaging
Pump and probe experiments
Multi energy imaging
High speed real time imaging
Scanning Transmission Electron Microscope
The Merlin readout electronics are based on a National Instruments PXI FPGA system with some additional custom control electronics. This is a robust, extensible and well supported platform with a long product lifetime. It integrates an embedded high performance industrial grade PC and FPGA card with 512GB dedicated RAM. 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.
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.
What is Medipix 3RX
Medipix3 is a 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.
WHAT IS CHARGE SUMMING MODE?
When a photon strikes near the edge of a pixel, the resulting charge may leak into neighbouring pixels by diffusion, sometimes below the threshold level. In some detector systems this information is mis-interpreted as lower energy photons on the pixels. Merlin is different and makes use of Medipix’s Charge Summing Mode. 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 ensures an accurate reading of the event giving improved results quality.
FREQUENTLY ASKED QUESTIONS
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.
The following video shows a Quad Merlin (512 x 512 pixels, 28.2 x 28.2mm) recording a rotating chopper at a frame rate of 1KHz with no deadtime.
- Pixel Size 55 x 55 μm
- Readout Time (continuous/12/24 bit) 0 μs / 850 μs / 1.8 μs
- Maximum Frame Rate (burst / continuous) 1.2 kHz / 100 Hz
- Dynamic Range 24 bit max
- Maximum Trigger Response Jitter 20 ns
- Threshold Range 5 keV upwards
- Exposure Time minimum 1 μs, no practical maximum
- Communication TCP / IP protocol
- Trigger 3.3 / 5 V TTL pulse
Merlin Paper Merlin: a fast versatile readout system for Medipix3