Study of saturable absorber materials for Q-switching dye laser

Q-switching is a technology widely used in lasers to generate short pulses with high peak powers. In practice, Q-switching can be realized with various methods including mechanically by rotating mirror, actively either by acousto-optic or electrooptic method, or passively using a saturable absorber. The first two techniques have their own problems especially the spinning machine and the driver to get a shorter pulse duration. Therefore, passive Q-switch was chosen in this study because it requires less optical element inside the laser cavity and no outside driving circuitry and makes this technique simple and relatively cheaper compared to the other two techniques. Passive Q-switching is a better choice for those applications where compactness of the laser is a prime requirement. The objective of this project is to study and characterize the suitable material to be saturable absorber for passive Q-switching laser. The dye laser was utilized as a source of Q-switching laser. As a preliminary, the laser was calibrated to determine the best performance of laser beam. Various materials including 3, 3’- Diethyloxadicarbocyanine Iodide (DODCI), 1,3'-Diethyl-4, 2’-quinolyloxacarbocyanine Iodide (DQOCI) and 1,1'-Diethyl-4, 4’-carbocyanine Iodide (Cryptocyannine) and Chromium-doped Yttrium Aluminium Garnet (Cr4+: YAG) crystal are employed as a saturable absorber material. The pulse width, the single pulse energy and the peak power of the Q-switched laser output are measured. Two of the tested materials namely 1,3'- Diethyl-4, 2’-quinolyloxacarbocyanine Iodide (DQOCI) and Chromium-doped Yttrium Aluminium Garnet (Cr4+: YAG) crystal demonstrate a good performance to be a saturable absorber. The output characteristics of the passive Q-switch laser possess a uniphase of TEM00 mode

An easy to use bluetooth scatternet protocol for fast data exchange in wireless sensor networks and autonomous robots

We present a Bluetooth scatternet protocol (SNP) that provides the user with a serial link to all connected members in a transparent wireless Bluetooth network. By using only local decision making we can reduce the overhead of our scatternet protocol dramatically. We show how our SNP software layer simplifies a variety of tasks like the synchronization of central pattern generator controllers for actuators, collecting sensory data and building modular robot structures. The whole Bluetooth software stack including our new scatternet layer is implemented on a single Bluetooth and memory chip. To verify and characterize the SNP we provide data from experiments using real hardware instead of software simulation. This gives a realistic overview of the scatternet performance showing higher order effects that are difficult to be simulated correctly and guaranties the correct function of the SNP in real world applications

Bluetooth Configuration of an FPGA: An Application to Modular Robotics

Self-reconfigurable modular robotics represents a new approach to robotic hardware. Instead of being designed as a huge centralized system, the “robot ” is composed of many simple, identical, interacting modules. With the help of some computation, sensing and communication capabilities, self-reconfiguring robots should be able to adapt their morphology to the environment in order to fulfill a desired task. The Biologically Inspired Group (BIRG) of the Swiss Federal Institute of Technology in Lausanne (EPFL) has developed a brand new Modular Robot called YaMoR. Each module contains an FPGA, a Bluetooth board, a power board, two batteries and a servo-motor. Assembling the modules together, a centralized Java application can supervise the overall movement via Bluetooth. The aim of the current semester project is to study the unexploited programming potential of the Bluetooth board, containing an ARM core, some Flash and some SRAM. In particular, we show how we can configure the FPGA board wirelessly. ii Acknowledgements First and foremost, I am deeply indebted to my supervisor, Andres Upegui. His encouragement, support, and advice have been immensely valuable. Moreover, he was always available when I needed help or suggestions. Special thanks go to Alessandro Crespi for his great help in electronics and in practical computing. I also owe a great debt to Andre Badertscher for his electronic work on the YaMoR modules and for the maintenance of the LSL lounge. Without him, I would have taken much more time on the solvering of the PCBs. I am also grateful to all the LSL team for their friendship and availability. It is really a pleasure to come every day at the laboratory when the atmosphere is so warm. A great thanks goes to Professor Auke Jan Ijspeert, who is always motivating people to work hard and consciously, by showing his interest. Finally, I have to thank all the people who have initiated this project, especiall

Learning to move in modular robots using central pattern generators and online optimization,”

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