<p>The aim of this master's thesis is to develop a method that fully automates a trimming step in the production of a fiber-optical power spectrometer, based on a unique Acusto-Optical Scanning Filter.</p><p>The filter is created by letting an ultrasonic mechanical pulse pass through a chirped Fiber Bragg Grating. The pulse introduces a disturbance in the grating, creating a thin optical transmission window in the otherwise reflective bandwidth. The high demands on the window requires a precise, unit dependent pulse form with unknown properties. Thus each unit needs to be trimmed to reach required performance.</p><p>The manual trimming is largely a trial and error process, that contains two performance tests. We redefine one, eliminating the need to reroute the optical path and reducing the number of fiber weldings. The tests are then quantified, allowing a figure of merit to be based on weighted performance values.</p><p>A brute force method, testing a large set of pulses, is implemented. The set is defined by the parameter space spanned by previously produced units. Due to the large space, the method is too time consuming. Instead it is used to measure the performance spaces of three units. An attempt to largely reduce the parameter space using PCA failed.</p><p>An alternating variables method that finds local performance optima in the parameter space is developed. By using a set of several starting points, the method tends to find several qualified pulses. The method is implemented and successfully verified by trimming new units.</p><p>Finally we propose where to focus improvements of the method in a production ramp up.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-121735 |
| Date | January 2009 |
| Creators | Forsslund, Ola |
| Publisher | Uppsala University, Signals and Systems Group |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, text |
| Relation | UPTEC F, 1401-5757 ; F09 047 |
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