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5 – ANALYSIS,

5 – ANALYSIS, CALCULATIONS AND EXPERIMENTS and the equality FV CA = P , the resulting FH length can be calculated with (4.2) to l = h 3 2fEb ≈ 13 mm. (5.2) P This length does not exceed the MSTS dimension requirement. But the defined thick- ness reaches the limit for blades manufactured by wire-cut EDM. Considering the technological limitations, the aspect ratio for l ≈ 13 mm follows to aF H = l h ≈ 260. (5.3) However, this ratio distinctly exceeds the maximum allowed ratio of aF H ≈ 60 dis- cussed in section 4.1.6. The MSTS design shall therefore be progressed in terms of the linear stage with necked down flexures. 5.5 Parallel Blade Stage VCA Based on the presented calculations, a test shutter consisting of a cylindrical single coil VCA and a stage with two parallel blades was constructed. The VCA parameters correspond to the values listed in table 5.2. As FH structure, a steel band with a thickness of 50 µm was cutted, folded and glued. Figure 5.5 shows the test shutter, where the cylindric magnet can be identified on the right side of the coil. The performed static measurements confirmed the calculated parameters. Further- more, the damping ratio could be measured, which is laborious to determine by means of FEM calculations. The test shutter setup shows a very weak damping ratio. This causes dozens of decaying oscillations of the FH structure when measuring the step response. So, a control electronics with well adjusted parameters will be inevitable for the MSTS. Albeit the simple construction of this test shutter, a lot of useful measurement data could be gathered and used for the MSTS design progress. Furthermore, the study an analysis results in terms of using a flexible hinge structure driven by a moving magnet VCA could be physically proved. A necessary step of improvement is to increase the first eigenfrequency for achiev- ing the required switching mode by broadening the blade thickness. Therefore, a higher Lorentz force will be needed for reaching an adequate stroke. Optimizing the different VCA parameters however rapidly voilated the requirements and boundary conditions. Thus, an alternative to the single coil VCA had to be found for the MSTS. 36

F VCA / mN 50 40 30 20 10 0 −10 −20 −30 −40 5 – ANALYSIS, CALCULATIONS AND EXPERIMENTS −50 −6 −4 −2 0 x / mm 2 4 6 Figure 5.4: Result of the single coil VCA force distribution measurement. A maximum Lorentz force of FV CA ≈ 43 mN can be generated with IC = 0.2 A. The magnet’s axial center must therefore be displaced to x ≈ ±2 mm relative to the coil’s axial center (x = 0). Figure 5.5: Photo of the test shutter consisting of a cylindrical single coil VCA and a stage with two parallel blades. 37

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