camBox – FPGA accelerated Image Processing for SwissFEL

SwissFEL_BeamProfile_02The Paul Scherrer Institute (PSI) in Villigen is planning the construction of a new X-ray light source, the so called Swiss Free Electron Laser (Swiss FEL). Thanks to its high time resolution (10-15s), the dynamic processes in solid state bodies as well as molecules shall be researched.

For Swiss FEL ray diagnostics, a novel image producing measuring system is being developed, in short called „camBox“, which captures the electron ray using 2D cameras, processing the images locally in real time. The relevant ray parameters as for instance the position or the width are being sent to the computer in the control room with a minimal latency.


Together with the PSI, a development plan has been established and worked out up to phase 3 ():

  1. Requirements and specifications hard- & software, algorithms, interfaces
  2. Design study → Evaluation of 5 solutions including a corresponding result
  3. Prototype development focusing on time savings → VME-FPGA-platform using standard components.
  4. Industrialization focusing on cost optimization → Linux PC with a independently developed FPGA-accelerator.

Since the beginning of 2013, the camBox prototype, engineered by SCS, is being tested at the PSI Institute. The project started in 2011.

Technical qualities of the camBox

Abbildung: camBox Architektur und Image Processing Pipeline

The camBox assumes the following tasks :

  • Analysing the ray profiles of camera pictures at frame rates up to 100Hz.
    • Correction of imaging artifacts:
      • Cosmics, Salt & Pepper noise
      • Offset- and background levels
      • Camera rotations: ± 5°, ±90°, 180°
  • Calculation of ray parameters
    • Ray profiles along the camera axis: x-profile, y-profile
    • Ray position: for example via the Center-of-Mass (CoM) or the brightest pixel
    • Width of ray: for example via Full-Width-%-maximum (FW%M), curve fitting
  • Support of the camera interface GigE Vision
  • Synchronisation via Event & Timing Logic of SwissFEL
  • Interface to EPICS
Abbildung: Hauptmodule der camBox (v.l.n.r): FPGA-Beschleuniger, Kamerainterface, VME Carrier






User Benefit

The camBox measures characteristic parameters of the SwissFEL electron ray in real time and transmits the collected data with a short latency to ray diagnostics located in the control center. These diagnostic data represent important control parameters for the control center – for the commissioning, the opting, the operation and the maintenance of the SwissFEL.

Further Use

The acceleration of image processing using FPGAs can typically be applied in cases where the speed of multi core processors or GPU solutions is insufficient. Also, FPGA-developments belong to our core competencies.

Contact person at SCS
Christof Bühler

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