Adaptive lenses enable compact, fast and quasi-motionless scanning in optical microscopy [1]. One drawback, however, is that the elements of an imaging system are usually optimized for a certain design-focal-length of the adaptive lens. In particular, spherical aberrations negatively influence the axial and lateral resolution as well as the signal strength in a confocal microscope. We address this problem using a novel fluid-membrane lens that is based on a piezo-glass composite membrane, where an ultrathin glass membrane is sandwiched between two piezo rings. With their two degrees of freedom, they can bend and buckle the membrane, enabling different rotated conic-section-like surfaces. An iterative control algorithm enables the simultaneous, independent tuning of the focal length and the induced spherical aberrations. We apply our adaptive lens in a confocal microscope that is extended with an additional phase measurement system to enable a wavefront-based control of the adaptive lens. Applying the aberration correction to a confocal measurement of a phantom yields an enhancement of
the axial resolution improvement compared to the uncorrected measurement. To investigate the usability of the system for biological specimen, we show confocal measurements at zebrafish embryos with reporter gene-driven fluorescence in the thyroid gland.
[1] Katrin Philipp, André Smolarski, Nektarios Koukourakis, Andreas Fischer, Moritz Stürmer, Ulrike Wallrabe, and Jürgen W Czarske, Volumetric HiLo microscopy employing an electrically tunable lens, Optics Express Vol. 24, Issue 13, pp. 15029-15041 (2016)
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