In this work, AlN and nanocrystalline diamond thin films as well as multi-layer structures on their basis are characterized towards their mechanical properties. In particular, the Young's modulus E and the residual stress s are obtained by wafer bow measurements of thin films as well as by bulge experiments and vibration measurements of freestanding membranes. Depending on the growth conditions, the AlN thin films, deposited by reactive magnetron sputtering, revealed values of s $ þ300 up to þ400 MPa and E $ 370 GPa, while the diamond films, grown by microwave plasma CVD, showed values of s $ À60 to þ60 MPa and E $ 870 up to 1000 GPa. The values and the accuracy of the characterization techniques used are discussed and their limits are demonstrated.

Blazed transmission gratings have become crucial components in many hybrid optical systems. Shadowing effects are known to occur at their passive blaze facets, which may impair the system's efficiency performance. For optical designs, it is desirable to have a simple but accurate description of this phenomenon. We show that the efficiency reduction in low diffraction orders is dominated by a linear dependence on the ratio of wavelength to grating period rather than a quadratic dependence as proposed in extended scalar theory. The strength of the electromagnetic shadowing will be determined using rigorous diffraction methods and discussed with respect to imaging optical components. Results are compared to existing ray-optical models.

New observations show a small difference between the sun's polar and equatorial limb darkening functions. This excess equatorial brightness varies in time and can be of sufficient magnitude to account for the solar oblateness inferred by Dicke and Goldenberg from their measurements. This removes the serious consequence of their work for Einstein's general theory of relativity. The problems of a solar-edge definition and the derivation of a solar mass quadrupole moment are discussed.

We present design and realization concepts for thin compound eye cameras with enhanced optical functionality. The systems are based on facets with individually tunable focus lengths and viewing angles for scanning of the object space. The active lens elements are made of aluminum nitride (AlN)/nanocrystalline diamond (NCD) membranes. This material system allows slow thermally actuated elements with a large deformation range as well as fast piezoelectric elements with a smaller deformation range. Due to the extreme mechanical stability of these materials, we are able to realize microoptical components with optimum surface qualities as well as an excellent long-term stability. We use facets of microlenses with 1 mm in diameter and a tunable focusing power to compensate for the focus shift for different viewing angles during the scanning procedure. The beam deflection for scanning is realized either by laterally shifting spherical elements or by a tunable microprism with reduced aberrations. For both actuators we present a design,fabrication concept and first experimental results

An f/100, 12.2-m focal length photoelectric telescope designed specifically for daytime astrometry of objects near the sun is now operative at its Tucson, Arizona, site. The design goal was to achieve accuracies of order 0.001 sec of arc in field position measurements of stars. To accomplish this, many features reducing systematic and random errors are employed, including Schupmann medial telescope optics, compensation for lateral color aberration, apodization for reduction of diffracted light, and use of an accurately measured solar diameter for calibrating the field.