Digital holographic two-wavelength contouring of high speed MEMS using ultrashort laser pulses

Konferenz: MikroSystemTechnik - KONGRESS 2007
15.10.2007 - 17.10.2007 in Dresden, Germany

Tagungsband: MikroSystemTechnik

Seiten: 4Sprache: EnglischTyp: PDF

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Hansel, Thomas; Steinmeyer, Günter; Grunwald, Rüdiger; Griebner, Uwe (Max-Born-Institut, Max-Born-Strasse 2a, D-12489 Berlin, Germany)
Falldorf, Claas; Kopylow, Christoph von (Bremer Institut für angewandte Strahltechnik BIAS, Klagenfurter Str. 2, D-28359 Bremen, Germany)
Bonitz, Jens; Kaufmann, Christian (Technische Universität Chemnitz, Reichenhainer Str. 70, D-09107 Chemnitz, Germany)

Single-shot digital holographic shape measurements of high-speed MEMS using femtosecond laser pulses are reported. To perform contouring of very fast moving objects the simultaneous generation of at least two spectrally separated ultrashort pulses is required. A chirped-pulse Ti:sapphire laser amplifier was modified to emit two femtosecond pulses of high spectral contrast at a separation of 10-15 nm. A Michelson-type interferometer was employed to perform stroboscopic two-wavelength-contouring. To record the two holograms of the MEMS with a resonance frequency of 0.5 kHz at once a multiplexing technique is applied. The phases of the holograms and the difference phases are numerically calculated. The resulting image contains a fringe pattern which allows to deduce the contour lines of the topology of the MEMS. Measurements of dynamic deformation at the MEMS resonance frequency are presented.