Several methods are being researched to detect and characterize buried nanoscale structures in hard solid samples. The most common acoustic method is acoustic microscopy. An acoustic microscope is based on a single element transducer operating in pulse-echo mode. The acoustic waves are coupled into a sample using a liquid couplant (eg water) and the beam is focused using a geometric lens to obtain a good lateral resolution. Thus, the frequency is limited by the attenuation in the coupling layer (water 3.5\{dB}/{m} at 4 GHz) and the typically low transmission coefficients at the transducer-liquid couplant and liquid-sample interfaces. Here, we present a novel method for high frequency acoustic metrology of buried structures in solid samples. The concept consisted of a 4 GHz acoustic transducer integrated above the tip of a custom designed probe. It operated in pulse-echo mode, and used solid-solid contact with the sample without the need for liquid coupling layers. A prototype was built and successfully tested experimentally on samples consisting of silicon with 1D and 2D arrays ofmu\{m} sized features buried below 5-10{m} of PMMA or SiO2 top layers. Moreover, a good match was obtained between model predictions and measurements of the pulse-echo performance of the novel GHz acoustic metrology method. The technique features a penetration depth of O(10s ofmu\{m}), is nondamaging and is not hampered by optically opaque layers.

Optical communications will complement radio frequency (RF) communications in the coming decades to enhance throughput, power efficiency and link security of satellite communication links. To enable optical communications technology for intersatellite links and (bi-directional) ground to satellite links, TNO develops a suite of technologies in collaboration with industry, which comprises of terminals with different aperture sizes, coarse pointing assemblies and fast steering mirrors. This paper presents the current state of the development of TNO technology for optical space communications. It mainly focuses on the development of an optical head with an entrance aperture of 70 mm, an optical bench for CubeSats and coarse pointing assemblies (CPAs). By continuing these steps, world wide web based on satellite communications will come closer.