In most Atomic Force Microscopes (AFM), a piezoelectric tube scanner is used to position the sample underneath the measurement probe. Oscillations stemming from the weakly damped resonances of the tube scanner are a major source of image distortion, putting a limitation on the achievable imaging speed. This paper demonstrates active damping of these oscillations in multiple scanning axes without the need for additional position sensors. By connecting the tube scanner in a capacitive bridge circuit the scanner oscillations can be measured in both scanning axes, using the same piezo material as an actuator and sensor simultaneously. In order to compensate for circuit imbalance caused by hysteresis in the piezo element, an adaptive balancing circuit is used. The obtained measurement signal is used for feedback control, reducing the resonance peaks in both scanning axes by 18 dB and the cross-coupling at those frequencies by 30 dB. Experimental results demonstrate a significant reduction in scanner oscillations when applying the typical triangular scanning signals, as well as a strong reduction in coupling induced oscillations. Recorded AFM images show a considerable reduction in image distortion due to the proposed control method, enabling artifact free AFM imaging at a speed of 122 lines per second with a standard piezoelectric tube scanner.

To overcome data rate limitations of RF communication links with satellites, TNO and DLR envision optical free-space communication feeder links for next generation high throughput satellites. This paper provides a feasibility assessment of such links and the technology needed. The main results of the link budget and the turbulence modeling of terabit/s optical links are presented. Based on these parameters, requirements and status of the link-subsystems are discussed, and a roadmap is presented, aimed at achieving terabit per second optical feeder links.

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The orientational order in the nematic phase of p-quinquephenyl, the pentamer of p-phenylene, has been determined by means of birefringence measurements and by wide-angle X-ray scattering (WAXS). The experimentally determined order parameters are compared with the temperature-dependent order parameter predicted by the Maier-Saupe theory. The order parameters derived from the birefringence at different temperatures in the nematic phase of p-quinquephenyl were in excellent agreement with the Maier-Saupe predictions. The values calculated from the azimuthal profiles derived from WAXS measurements were significantly lower than those determined by the birefringence measurements, especially at higher temperatures. For the birefringence measurements, alignment of the director is achieved by using polyimide alignment layers, whereas director alignment for the WAXS experiments was achieved by a magnetic field. We assign the low overall order parameters that were measured by WAXS to a lower macroscopic orientational order. In addition, upon reinvestigating the mesophase behavior of p-quinquephenyl, a monotropic smectic A phase has been observed upon cooling at 390 °C, just before the crystallization temperature is reached.

Over the last decade TNO has developed a deformable mirror concept using electromagnetic actuators with the main advantages of having very low non-linearity and hysteresis, low power consumption, and high inherent reliability of the actuators. TNO recently started a program to redesign the electromagnetic actuator to improve the actuator efficiency, allowing higher actuator force per volume and per wattage. The increased actuator efficiency gives improvement of the DM performance in terms of dynamical performance, actuation range, and power dissipation. With this technology various applications in the fields of ground-based astronomy and space missions are targeted.