Publications by authors named "U Wallrabe"

Conventional microscopes have a high spatial resolution and a low depth-of-field. Light field microscopes have a high depth-of-field but low spatial resolution. A new hybrid approach uses information from both systems to reconstruct a high-resolution light field [Appl.

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Various techniques in microscopy are based on point-wise acquisition, which provides advantages in acquiring sectioned images, for example in confocal or two-photon microscopy. The advantages come along with the need to perform three-dimensional scanning, which is often realized by mechanical movement achieved by stage-scanning or piezo-based scanning in the axial direction. Lateral scanning often employs galvo-mirrors, leading to a reflective setup and hence to a folded beam path.

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We present a simple method to determine the refractive index of fluids that is suitable for real-time integrated measurements by imaging a collimated beam through a fluid volume and determining its diameter on a CMOS sensor. Our experimental results agree with the prediction of our analytical model, and the resulting refractive index agrees with the measurements obtained with a commercial refractometer with an RMS deviation of just ±0.003.

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We present a compact adaptive glass membrane lens for higher order wavefront correction and axial scanning, driven by integrated segmented piezoelectric actuators. The membrane can be deformed in a combination of rotational symmetry providing focus control of up to ± 6 m and spherical aberration correction of up to 5 wavelengths and different discrete symmetries to correct higher order aberrations such as astigmatism, coma and trefoil by up to 10 wavelengths. Our design provides a large clear aperture of 12 mm at an outer diameter of the actuator of 18 mm, a thickness of 2 mm and a response time of less than 2 ms.

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We demonstrate a method for self-sensing of a magnetically actuated prism that can be used, e.g., in a feedback-loop without the need of additional sensors.

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