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End date: 2015 × Subject: Adaptive optics ×

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    Adaptive micro axicons for laser applications
    (Les Ulis : EDP Sciences, 2015) Wallrabe, Ulrike; Brunne, Jens; Treffer, Alexander; Grunwald, Ruediger; Bellouard, Yves
    We report on the design, fabrication and testing of novel types of low-dispersion axicons for the adaptive shaping of ultrashort laser pulses. An overview is given on the basic geometries and operating principles of our purely reflective adaptive MEMS-type devices based on thermal or piezoelectric actuation. The flexible formation of nondiffracting beams at pulse durations down to a few oscillations of the optical field enables new applications in optical communication, pulse diagnostics, laser-matter interaction and particle manipulation. As an example, we show first promising results of adaptive autocorrelation. The combination of excellent pulse transfer, self-reconstruction properties and propagation invariance of nondiffracting beams with an adaptive approach promises to extend the field of practical applications significantly.
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    The Wave-Front Correction System for the Sunrise Balloon-Borne Solar Observatory
    (Dordrecht [u.a.] : Springer Science + Business Media, 2010) Berkefeld, T.; Schmidt, W.; Soltau, D.; Bell, A.; Doerr, H.P.; Feger, B.; Friedlein, R.; Gerber, K.; Heidecke, F.; Kentischer, T.; von der Lühe, O.; Sigwarth, M.; Wälde, E.; Barthol, P.; Deutsch, W.; Gandorfer, A.; Germerott, D.; Grauf, B.; Meller, R.; Álvarez-Herrero, A.; Knölker, M.; Pillet, V.M.; Solanki, S.K.; Title, A.M.
    This paper describes the wave-front correction system developed for the Sunrise balloon telescope, and it provides information about its in-flight performance. For the correction of low-order aberrations, a Correlating Wave-Front Sensor (CWS) was used. It consisted of a six-element Shack - Hartmann wave-front sensor (WFS), a fast tip-tilt mirror for the compensation of image motion, and an active telescope secondary mirror for focus correction. The CWS delivered a stabilized image with a precision of 0.04 arcsec (rms), whenever the coarse pointing was better than ± 45 arcsec peak-to-peak. The automatic focus adjustment maintained a focus stability of 0.01 waves in the focal plane of the CWS. During the 5.5 day flight, good image quality and stability were achieved during 33 hours, containing 45 sequences, which lasted between 10 and 45 min. © 2010 The Author(s).