We present two piezo-actuated adaptive prisms with apertures of 8 mm based on a bi-axial continuously tiltable glass window on top of an optical fluid, enabling fast scanning applications in a compact, linear axial design. One prism with a device size of 58 by 51 mm is optimized for scan angles of ±6.4° and response times of 2.5 ms. A second compact prism uses spiral-shaped actuators to achieve a reduced device diameter of 33 mm at slightly compromised maximum scan angles of ±4.0° with response times of approximately 4 ms. We show the design and FEM-based optimization of the prisms, their fabrication and the characterization of the scan angles and of the dynamic behavior. Finally, we also demonstrate the linearity of the system and discuss a simple control model.

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⁻¹ 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.

We present the development of a dual-mode imaging platform that combines optical microscopy with magnetic resonance microscopy. Our microscope is designed to operate inside a 9.4T small animal scanner with the option to use a 72mm bore animal RF coil or different integrated linear micro coils. With a design that minimizes the magnetic distortions near the sample, we achieved a field inhomogeneity of 19 ppb RMS. We further integrated a waveguide in the optical layout for the electromagnetic shielding of the camera, which minimizes the noise increase in the MR and optical images below practical relevance. The optical layout uses an adaptive lens for focusing, 2 × 2 modular combinations of objectives with 0.6mm to 2.3mm field of view and 4 configurable RGBW illumination channels and achieves a plano-apochromatic optical aberration correction with 0.6μm to 2.3μm resolution. We present the design, implementation and characterization of the prototype including the general optical and MR-compatible design strategies, a knife-edge optical characterization and different concurrent imaging demonstrations.

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. In this paper, we introduce a fully refractive microscope capable of three-dimensional scanning, which employs the combination of an adaptive lens, an adaptive prism, and a tailored telecentric f-theta objective. Our results show that this microscope is capable to perform flexible three-dimensional scanning, with low scan-induced aberrations, at a uniform resolution over a large tuning range of X=Y=6300 μm and Z=480 μm with only transmissive components. We demonstrate the capabilities at the example of volumetric measurements on the transgenic fluorescence of the thyroid of a zebrafish embryo and mixed pollen grains. This is the first step towards flexible aberration-free volumetric smart microscopy of three-dimensional samples like embryos and organoids, which could be exploited for the demands in both lateral and axial dimensions in biomedical samples without compromising image quality.

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. In order to use the impedance of the actuation coils as a measurement parameter, we first obtained the optimal measurement frequency that is well separated from the actuation frequencies and at the same time provides the best compromise between sensitivity to the position and robustness. We then developed a combined actuation and measurement driver, and correlated its output signal to the mechanical state of the prism using a defined calibration sequence. We demonstrate that we can reliably measure the state of each actuator and determine the tilt angle of the prism with an accuracy of $\pm 0.1$${}^{\circ }$ in the polar angle over a range of $\pm 4$${}^{\circ }$ and $\pm 20$ mrad in the azimuthal angle.

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. This method requires only inexpensive components: a light source, two lenses, and a camera sensor; it is suitable for real-time monitoring, and it is essentially unlimited in the range of refractive indices.