The silicon LAMBDA system is specifically designedfor synchrotron experiments requiring high spatial resolution, high sensitivity and extremely high speed. This makes it well-suited to applications such as XPCS, time-resolved measurements, ptychography, SAXS, Diamond anvil cells and imaging.LAMBDA is based on the Medipix3 readout chip, developed at CERN. By using single-photon-counting circuitry, this provides effectively noise-free operation, which is particularly critical for achieving a high image quality during fast measurements and discriminating against fluorescence. This photon-counting feature is combined with a small pixel size (55 µm) for high-resolution imaging, and flexible in-pixel circuitry.
Different operation modes
The LAMBDA system can be operated in a variety of modes:High-speed readout mode at up to 2000 frames per second, with no dead time between images24-bit counter depth mode, with 1 ms readout time between imagesEnergy binning mode; photon hits are divided into two user-defined energy bins. This can be used, for example, to discriminate between the first beam harmonic and higher harmonics.The LAMBDA readout electronics, developed at DESY, make it possible to read out a large 750K module at 2000 frames per second rate using high-speed optical links.
LAMBDA with High-Z sensor is well suited for energies above 20 keV
X-Spectrum has developed versions of the LAMBDA system where the silicon sensor is replaced with one of the “high-Z“ materials, Gallium Arsenide (GaAs) or Cadmium Telluride (CdTe), which provide greater detection efficiency at high X-ray energies. With these sensors, the LAMBDA system combines efficient hard X-ray detection with zero noise, high spatial resolution and high speed. In particular, the 2000 frames per second readout of a high-Z LAMBDA system is more than 1000 times faster than a typical flat-panel detector, enabling time-resolved hard X-ray experiments on millisecond timescales.
Sensor material: Gallium Arsenide or
As shown to the right, Cadmium Telluride has higher quantum efficiency than Gallium Arsenide at higher X-ray energies, so it is the natural choice for experiments at 60 keV and above. However, CdTe also strongly re-emits fluorescence photons around 25-30 keV when illuminated with higher-energy photons, which can reduce the detected signal and slightly blur the image. So, GaAs is beneficial in the 25 – 50 keV range. After flat-field correction, GaAs sensors also deliver better image uniformity.
Pixel design: High resolution (55 µm) or colour imaging (110 µm)
All our detectors are available with a fine pixel pitch of 55 µm and the capability to divide photon hits into two energy bins. Upon request we provide colour imaging versions of the LAMBDA system, which increase the maximum number of energy bins to 8, at the expense of a larger pixel size of 110 µm. Please contact us for details.
The detector unit is provided with a compact power supply and most systems require only air cooling, making it convenient to mount the camera on movable stages. The detector can be externally triggered during operation.During operation, the LAMBDA system is controlled by a server PC, which processes and stores images received from the detector. The detector can be controlled and monitored at the beamline using the Tango control system. Images are saved using the HDF5 format, which saves an entire image series to a single file along with image metadata. This approach makes it possible to perform high-speed imaging without creating excessive numbers of files. The file can then be accessed by standard functions in C, Python, MATLAB, IDL and other languages.To customers that what to implement their own control systems we provide a hardware library that allows to control the camera from many operating systems..