W. Cichalewski

Analytical modelling and simulations of a MEMS micro-mirror - MATLAB implementation

This paper is devoted to the study of the static and dynamical behaviour of a ID torsion single crystal silicon micro-mirror. The aim is to create a parametric model of such mirror allowing to use a simple calculation program to avoid expensive and long FEM simulations. This study tries to put in place a modelling to define the best structure with regard to various specification by taking into account the technological possibilities and to simulate the experimental characteristics before the expensive technological process.

Real time control of RF fields using a MicroTCA.4 based LLRF system at FLASH

The Free Electron Laser in Hamburg (FLASH) is a large scale user facility, providing highly stable and brilliant laser pulses down to a wavelength of 4.1 nm. Essential for stable and reproducible photon beam is the precision control of the electron bunch parameters. The acceleration principle of the electron bunches at FLASH is based on superconducting RF technology (SRF), in which the RF fields are controlled by a digital low level RF (LLRF) system. This system has been recently upgraded to the Micro Telecommunication Computing Architecture (MicroTCA.4) to improve the performance of the field regulation. This paper presents the first measurements and operation experiences using this new electronic crate standard at a large scale research facility. RF field regulation is carried out by real time fast digital processing on several boards in a MicroTCA.4 crate, and slow automation routines running on a dual core i7 front-end CPU. Scalability and modularity of this system is one of the key parameters to meet the next steps, namely being the platform standard for the European X-ray free electron laser currently build at DESY.

Design and implementation of LLRF station software suite in Distributed Control System used in E-XFEL

The European XFEL project is a free electron linear particle accelerator located in Hamburg, Germany, currently being developed by DESY and to be launched later this year. The particle accelerator is controlled by RF control system, built as a chain of RF stations bound to cryomodules across the tunnel. Each RF station has a set of additional devices, that are used to control particular parts of the system. The core library for device module handling was designed using Distributed Objected Oriented Control System (DOOCS) framework as a base, and then it was extended by implementing component software pattern design, thus allowing simplified and universal way of handling communication with the hardware, as well as handling other tasks such as data validation and application logic. The library is implemented by using modern C++11/14 standards and utilizing Boost library features where necessary. The server applications utilize the library to provide common device access by using Chimera Tool Kit, as well as other register-based protocols like Simple Network Management Protocol (SNMP). In addition to the core library, two device-specific libraries were created to provide the flexibility of embedding them into third party DOOCS server applications if needed.

FPGA based RF and piezo controllers for SRF cavities in CW mode

Modern digital low level radio frequency (LLRF) control systems used to stabilize the accelerating field in facilities such as Free Electron Laser in Hamburg (FLASH) or European X-Ray Free Electron Laser (E-XFEL) are based on the Field Programmable Gate Array (FPGA) technology. Presently these accelerator facilities are operated with pulsed RF. In future, these facilities should be operated with continuous wave (CW) which requires significant modifications on the real-time feedbacks realized within the FPGA. For example, higher loaded quality factor of the cavities when operated in a CW mode requires sophisticated resonance control methods. However, iterative learning techniques widely used for machines operated in pulsed mode are not applicable for CW. In addition, the mechanical characteristic of the cavities have now a much more important impact on the choice of the feedback scheme. To overcome the limitations of classical PI-controllers novel realtime adaptive feed forward algorithm is implemented in the FPGA. Also, the high power RF amplifier which is an inductive output tube (IOT) for continuous wave operation instead of a klystron for the pulsed mode has major impact on the design and implementation of the firmware for regulation. In this paper, we report on our successful approach to control multi-cavities with ultra-high precision (dA/A<;0.01%, dphi<;0.02 deg) using a single IOT source and individual resonance control through piezo actuators. Performance measurements of the proposed solution were conducted at Cryo Module Test Bench (CMTB) facility.

Polish electronics in high energy physics & aerospace technology

The paper presents the way that colour can serve solving the problem of calibration points indexing in a camera geometrical calibration process. We propose a technique in which indexes of calibration points in a black-and-white chessboard are represented as sets of colour regions in the neighbourhood of calibration points. We provide some general rules for designing a colour calibration chessboard and provide a method of calibration image analysis. We show that this approach leads to obtaining better results than in the case of widely used methods employing information about already indexed points to compute indexes. We also report constraints concerning the technique. Nowadays we are witnessing an increasing need for camera geometrical calibration systems. They are vital for such applications as 3D modelling, 3D reconstruction, assembly control systems, etc. Wherever possible, calibration objects placed in the scene are used in a camera geometrical calibration process. This approach significantly increases accuracy of calibration results and makes the calibration data extraction process easier and universal. There are many geometrical camera calibration techniques for a known calibration scene [1]. A great number of them use as an input calibration points which are localised and indexed in the scene. In this paper we propose the technique of calibration points indexing which uses a colour chessboard. The presented technique was developed by solving problems we encountered during experiments with our earlier methods of camera calibration scene analysis [2]-[3]. In particular, the proposed technique increases the number of indexed points points in case of local lack of calibration points detection. At the beginning of the paper we present a way of designing a chessboard pattern. Then we describe a calibration point indexing method, and finally we show experimental results. A black-and-white chessboard is widely used in order to obtain sub-pixel accuracy of calibration points localisation [1]. Calibration points are defined as corners of chessboard squares. Assuming the availability of rough localisation of these points, the points can be indexed. Noting that differences in distances between neighbouring points in calibration scene images differ slightly, one of the local searching methods can be employed (e.g. [2]). Methods of this type search for a calibration point to be indexed, using a window of a certain size. The position of the window is determined by a vector representing the distance between two previously indexed points in the same row or column. However, experiments show that this approach has its disadvantages, as described below. * E-mail: A.Nowakowski@ire.pw.edu.pl Firstly, there is a danger of omitting some points during indexing in case of local lack of calibration points detection in a neighbourhood (e.g. caused by the presence of non-homogeneous light in the calibration scene). A particularly unfavourable situation is when the local lack of detection effects in the appearance of separated regions of detected calibration points. It is worth saying that such situations are likely to happen for calibration points situated near image borders. Such points are very important for the analysis of optical nonlinearities, and a lack of them can significantly influence the accuracy of distortion modelling. Secondly, such methods may give wrong results in the case of optical distortion with strong nonlinearities when getting information about the neighbouring index is not an easy task. Beside this, the methods are very sensitive to a single false localisation of a calibration point. Such a single false localisation can even result in false indexing of a big set of calibration points. To avoid the above-mentioned problems, we propose using a black-and-white chessboard which contains the coded index of a calibration point in the form of colour squares situated in the nearest neighbourhood of each point. The index of a certain calibration point is determined by colours of four nearest neighbouring squares (Fig.1). An order of squares in such foursome is important. Because the size of a colour square is determined only by the possibility of correct colour detection, the size of a colour square can be smaller than the size of a black or white square. The larger size of a black or white square is determined by the requirements of the exact localisation step which follows the indexing of calibration points [3]. In this step, edge information is extracted from a blackand-white chessboard. This edge information needs larger Artur Nowakowski, Wladyslaw Skarbek Institute of Radioelectronics, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warszawa, A.Nowakowski@ire.pw.edu.pl Received February 10, 2009; accepted March 27, 2009; published March 31, 2009 http://www.photonics.pl/PLP

Application of microelectronics in high energy physics and space technology

Department of Microelectronics and Computer Science of Lodz University of Technology has long traditions and high expertise in field of design of electronic systems of various kinds and for several applications. DMCS has expertise in design of PCB (Printed Circuit Board) based and ASIC (Application Specific Integrated Circuit) based analog, mixed-signal and digital system designs. DMCS design teams participated in numerous national and international scientific research programs and grants. A series of commercial contracts was also conducted in DMCS. Many of these works finished with introduction of new systems into scientific installations or putting new product into general markets. Several DMCS achievements have been successfully patented. Such extensive experience in connection with wide field of scientific activities, enabled application of DMCS capabilities to quite different and even unusual electronic system applications aimed at work in extreme environments.

Superconducting cryo-modules characterization for European XFEL - LLRF tests in AMTF

The paper describes achievements in LLRF based tests preparation for superconducting cryo-modules evaluation for European X-ray Free Electron Laser. The software for automatic cryo-modules characterization at the Accelerator Module Test Facility (AMTF) will be presented. In order to identify fundamental working parameters of the eight TESLA cavities cryomodules the scenario of several tests sequence has been proposed and implemented in AMTF. Main parameters like: cavities quenching levels verification, cavities Pi modes identification, slow and fast frequency tuners performance, fundamental power coupler performance, etc are evaluated. Basing on achieved data the decision about module acceptance for work in the linac is done. In this solution the MTCA.4 based LLRF system is used to control and verify cryo-string performance. Middle layer client servers implemented in this environment are responsible for providing tests initial conditions, testing and results archiving in the dedicated data base. Results of described tests are not only vital for module acceptance but are also important for future LLRF system set-up and configuration concerning module work in the accelerator tunnel.