Düsseldorf 2007 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 43: Optische Messtechnik
Q 43.2: Vortrag
Mittwoch, 21. März 2007, 14:15–14:30, 5E
Simultaneous generation of two spectrally separeted ultrashort pulses for 2-lambda contouring with digital holography — •Thomas Hansel1, Günter Steinmeyer1, Rüdiger Grunwald1, Uwe Griebner1, Claas Falldorf2, Jan Müller2, Christoph von Kopylow2, and Werner Jüptner2 — 1Max-Born-Institut, Max-Born-Strasse 2a, D-12489 Berlin, Germany — 2Bremer Institut für angewandte Strahltechnik BIAS, Klagenfurter Str. 2, D-28359 Bremen, Germany
Digital holographic shape measurements 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 sub-50 fs Ti:sapphire laser system was modified to emit two pulses with a variable spectral separation around 800 nm. The spectrum of a single fs-pulse of the laser system was altered by a prism line and a variable double slit, resulting in two distinct wavelength peaks. Each pulse had a spectral width of about 13 nm, and the spectral difference could be chosen within the 50 nm bandwidth (FWHM) of the original pulse spectrum. A Michelson-type interferometer was then applied to perform 2-lambda-contouring. The phases of the holograms and the difference phases are calculated numerically. The resulting image contains a fringe pattern that can be interpreted as contour lines of the topology of the object. Results for distinct stationary objects are presented. The possibility to record two holograms at once using two synchronized CCD-cameras is discussed.