Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 16: Poster Session I

BP 16.3: Poster

Tuesday, March 27, 2007, 17:00–19:30, Poster D

Fast and Light-Efficient Wavefront Sensing — •Marcel Andreas Lauterbach, Markus Rueckel, and Winfried Denk — Max Planck Institute for Medical Research, Department of Biomedical Optics, Jahnstr. 29, 69120 Heidelberg, Germany

Adaptive Optics can improve the image quality of confocal/multi-photon microscopic images by correcting wavefront distortions of the excitation beam. The wavefront distortions can originate from the sample itself and must be measured for correction. The wavefront sensing should be light-efficient to allow fast correction and to avoid photodamage in the biological sample during the measurement process.

We developed an interferometer-based virtual modal wavefront sensor (VMWS) that can be configured to measure, for example, Zernike coefficients directly. This sensor is particularly light efficient. Including up to Zernike mode 21, aberrations can be determined with a precision of about 0.17 rad (λ/37) using low resolution (65 * 65 pixels) images and only about 400 photons total.

The VMWS uses Phase Shifting Interferometry (PSI), for which we developed a new scheme ("Nonlinear PSI" (NPSI)), which makes faster measurements possible. It allows an almost arbitrary reference phase shift during the interferogram recording. We especially investigated the case of a sinusoidal phase shift. We show results of wavefront measurements and the comparison with theoretical considerations and envision the applicability of the VMWS and NPSI to confocal/multi-photon microscopy. VMWS and NPSI are not limited to microscopy but should be applicable whenever a reference wavefront is available.