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Proceedings Paper

Time-resolved two-wavelength contouring of adaptive fluidic PDMS-lenses
Author(s): Thomas Hansel; Ruediger Grunwald; Günter Steinmeyer; Uwe Griebner; Florian Schneider; Ulrike Wallrabe
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Paper Abstract

We present a synthesized sub-ps dual-wavelength laser source for digital holographic interferometry with a wide reconstruction range. The developed laser source generates two spectrally separated parts within one pulse. The sub-ps pulse duration desensitizes the holographic setup to environmental impacts. A center wavelength distance of only 12 nm with a high contrast was demonstrated by spectral shaping of the 50 nm broad seed spectrum of a CPA Ti:sapphire laser system centered at 800 nm. Time-resolved two-wavelength contouring requires the simultaneous and separable recording of two holograms. In general, a single CCD-camera is applied, and the spectral separation is realized by different reference wave tilts, which requires ambitious interferometric setups. Contrary to this, we introduce two CCD-cameras for digital holographic recording, thus essentially simplifying the interferometric setup by the need of only one propagation direction of the reference wave. To separate the holograms for the simultaneous recording process, a Mach-Zehnder interferometer was extended by a polarization encoding sequence. To study our approach of time-resolved digital holographic two-wavelength contouring, an adaptive fluidic PDMS-lens with integrated piezoelectric actuator served as test object. The PDMS-lens consists of an oil-filled lens chamber and a pump actuator. If a voltage is applied to the piezoelectric bending actuator the fluid is pumped into the lens chamber which causes a curvature change of the 60-μm thick lens membrane and thus a shift of the focal length. The dynamic behavior of the PDMS-lens, driven at a frequency of 1 Hz, was investigated at a frame rate of 410 frames per second. The measured temporal change of the lens focal length between 98 and 44 mm followed the modulation of the piezoelectric voltage with a 30 V peak-to-peak amplitude. Due to the performed time-resolved two wavelength contouring, we are able to extract the optical path length differences between center and perimeter of the lens. From the calculated phase difference maps we estimated large optical path differences of larger than 10 μm, corresponding to more than 15 times of the source wavelength.

Paper Details

Date Published: 19 May 2009
PDF: 9 pages
Proc. SPIE 7358, Holography: Advances and Modern Trends, 735809 (19 May 2009); doi: 10.1117/12.820698
Show Author Affiliations
Thomas Hansel, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (Germany)
Ruediger Grunwald, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (Germany)
Günter Steinmeyer, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (Germany)
Uwe Griebner, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (Germany)
Florian Schneider, Albert-Ludwigs-Univ. Freiburg (Germany)
Ulrike Wallrabe, Albert-Ludwigs-Univ. Freiburg (Germany)


Published in SPIE Proceedings Vol. 7358:
Holography: Advances and Modern Trends
Miroslav Miler; Miroslav Hrabovský, Editor(s)

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