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1 September 2006 Characterization of novel optical fibers for use in laser detonators
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A system for launching flyers using a Q-switched Nd: YAG laser has been developed for shock initiation of secondary explosives. Flyers have been launched at velocities approaching 6 km s-1. Optical fibers are used to transport the optical energy from the laser to the detonator. The launch of these flyers with sufficient velocity requires a fluence in the region of 35 J cm-2, significantly above the damage threshold of most optical fibers. This damage is typically caused by laser absorption at the input face due to imperfections in the surface polishing. A variety of optical fibers with high quality input faces have been tested at fluences up to 50 J cm-2, and their damage thresholds and beam profiles have been measured. The standard fiber used in this system is a low hydroxyl (-OH) content, 400μm diameter core silica fiber, with CO2 laser polished faces. In addition to this, fibers tapering down to 300μm and 200μm core diameter were investigated, as a means of increasing the efficiency of the system, along with mechanically polished fibers. The fiber currently enters the detonator body from the rear. Depending on the application, it may be required for the fiber to enter from the side. To facilitate this, fibers with a machined output face, designed to produce an output at approximately 90 degrees to the fiber axis were tested. Finally, a 2:1 fiber splitter was tested, as a first step to enable simultaneous firing of several detonators. Multiple initiation points are desirable for applications such as programmable initiation, and it is intended to study fiber splitters with a higher split ratio, such as 4:1 and 8:1. The results of these experiments are presented, and assessments made of suitability for transmission of high-power Qswitched Nd:YAG laser pulses.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. D. Bowden, R. C. Drake, and C. A. Singleton "Characterization of novel optical fibers for use in laser detonators", Proc. SPIE 6287, Optical Technologies for Arming, Safing, Fuzing, and Firing II, 628701 (1 September 2006);

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