LASI Laboratory for Advanced Sensors and Instrumentation
Timing Systems based on Optical Technology
The main goal was to develop and to study technical possibilities for developing of equipment for precision time and frequency transfer for synchronizing different physical experiments and measurements. Modern technology favors the transfer of such signals using optical fibers. Glass optical fibers have many excellent physical properties but also a few drawbacks. The most expressed drawback for example is thermal elongation of the fiber that significantly changes propagation delay time. External influences on the electronics that is converting electrical into optical signal or vice-versa additionally decrease the quality of the signal, being transferred. The negative effects have to be taken into account by the proposed equipment. They have to compensated and/or completely eliminated. An additional goal is the integration of the developed equipment with the requirements from the users, in particular with innovative sensors and corresponding electronics and optics. A demanding equipment was needed for signal observation and measurement in this project (spectrum analyzers, signal source analyzers, polarization dispersion meters). Some of this equipment was owned by COBIK, the rest was borrowed from the founders of COBIK. Nevertheless, the laboratory has enough expertize and equipment available to develop entirely new electronic, microwave and electro-optical systems.
|Improvements of the reference signal transfer system||Development of a single-fiber reference signal transfer system|
|Upgrade of the reference signal transfer system with a fiber spool, used for slow temperature drift compensation.|
|Testing of a directly modulated laser source|
|Testing of new concepts of reference sygnal transfer||Transition to higher frequencies|
|Compensation of optical path changes for an arbitrary signal transfer|
|Testing of chain of multiple optical signal delivery points|
|Fast compensation of optical path changes
(new activity, patent request filed-in)
|High stability phase detector
(new activity – prototype developed)
|Optical fiber wounding machine for demanding optical systems (new activity – innovation reported)|
|Long-term stable and low-noise 3 GHz reference signal generator||Reduction of the close-in phase noise|
|Study of operation and performance of higher (5th, 7th) overtone low-noise oscillators|
|Reduction of oscillator's slow drift|
|Testing of a low-noise oscillator with a fiber-optics delay line (new activity)|
Figure 1: A prototype of an improved low-noise oscillator
Figure 2: A prototype of fast compensation for optical path changes
Figure 3: A prototype of a high-stability phase detector
Distributed System Techniques
The main goal of the research activities was a better understanding of the main building blocks of the distributed control system architecture. The comparative analysis with the non-distributed architecture revealed the economical and technical differences. It is expected that fully synchronized distributed sampling and processing systems would make integration of instrumentation for large facilities easier and also more economical. The research was focused towards general solutions to the problems mentioned above, but at the same time it had to refer to a more specific case (transfer of high-speed acquired signal). A significant part of the research activities was dedicated to evaluation and selection of optical and electro-optical components that are to will be used in the distributed systems. New evaluation and measurement methods for these components needed to be developed first. A prototype system was intended to demonstrate simultaneous transfer of the reference and acquisition signal over the same fiber. This system automatically measures and compensates differences in path length from the central point to peripheral acquisition units.
In this project, mostly equal tools and instrumentation are used as in the »Timing System based on Optical Technologies«.
|Identification and developement of building blocks for the distributed processing||Concept selection and development of a deterministic, low-latency connection for distances up to 2 km|
|Upgrade to the synchronization system (TSTO) between the units to be able to transfer absolute time|
|Selection and building a prototype of data transfer to a distance up to 2 km using a non-deterministic connection.|
|Implementation of the system for the absolute time mark distribution.|
|Phase shifter with a reduced influence of electronic components – a digital method for the reference signal phase change (new activity, patent request filed-in)|
Figure 4: Block diagram of a distributed processing system
Figure 5: Test of optical components, intended for use at simultanous transfer of multiple signals over single optical fiber.
Sampling with Embedded Super-Computing
The main goal of the research activities was to increase the processing capacity of the high performance sampling units, which produce high data rates due to fast sampling of multiple channels. The existing solutions with custom FPGA designs are superior to other solutions in terms of latency and speed, but tend to be non-economical in terms of development time, power consumption and component costs. The optimal solution to our problem was to combine the sampling unit with an embedded computational unit. The latter approach was much more economical with only slightly higher latency. The goal of the research on the combined sampling-processing architecture is to increase the capacity of digital signal processing by a factor of 10 to 100 regarding the effort, invested into programming. The application of a selected processing architecture based on a research of performance of various architectures (FPGA, DSP, GPU, combination of those). A test of operation of a graphical processing unit (GPU) in processing of real-time sampled signals has been performed.
Equipment, required in this project consists of FPGA development boards, GPU units (two already owned by COBIK) and equipment for acquisition and analysis of fast digital signals.
|Processing unit architectures for specific algorithms to be used with aims of applying advanced programming methods, reduction of data rates and connecting the processing units to the sampling units.
||Selection of architectures for specific algorithms. Selection of interfaces and connections to the acquisition units.|
|A prototype project using the selected processing units and interfaces|
Figure 6: A test of a GPU, connected to the acquisition unit
Single Cristal Diamond based Sensors
A single-crystal diamond (SCD) material is suitable for application of new sensors, in particular of the photon beam position (X-BPM) sensor, operating at the accelerating structure RF frequency (a few 100 MHz). Research included procedures for classification of material, research in homogeneity, surface treatment, lithography and metallization fields and manufacturing of micro connectors. The main goals of the research was to define SCD sensor’s technology basis, to define concepts of signal acquisition and detection of relevant sensor’s characteristics changes, to find surface characteristics of chemically activated mono-crystal diamond. Most of these procedures are already implemented in semiconductor technology. With diamond material these procedures are more demanding because of its specific characteristics (high mechanical durability, chemical inertia and other extreme characteristics).
|Extension of the photon beam position measurement unit family. Gain of technological expertise for the application of SCD in biosensors.||Development of material characterization and development of technology of surface treatment and metal deposition to the SCD raw material|
|Development of X-BPM sensor|
|Transfer of technological expertise to the biosensors area|
Figure 7: Encapsulated prototype of X-BPM sensor
Figure 8: X-BPM sensor stand during a live test on a beamline
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