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Different applications of aspheric optics and their related fabrication methods are firstly summarized and then discussed using Carl Zeiss examples. This is done in order to highlight the potential and challenges of fabricating aspheric optics. The need to stimulate new ideas for extending manufacturing capabilities, process improvements and new fabrication technologies will also be outlined.

Since 1974 X-ray optics and optical ground support equipment for various national and international X-ray and EUV- missions have been designed, manufactured, tested and delivered by Carl Zeiss/Oberkochen. The range of X-ray optics includes mirror systems for ASTRO 8, ROSAT and ABRIXAS, as well as mandrels for SAX, JET-X, WFXT, XMM, Constellation-X and XEUS. An example for high quality EUV- systems is the Wolter II mirror system for SOHO-CDS. We will give a retrospect to previous programs, report about recently performed and finished X-ray optics, as well as we will give an outlook for future contributions.

The Joint European X-Ray Telescope, JET-X, is one of the core instruments of the scientific payload of the Russian SPECTRUM-X astrophysics mission due for launch in 1995. JET-X is designed to study the emission from X-ray sources in the band from 0.3 to 10 keV, particularly to meet primary scientific goals in cosmology and extragalactic astronomy. JET-X consists of two identical, coaligned X-ray imaging telescopes, each with a spatial resolution of 30 arcsecond (Half Energy Width, HEW) or better. Each telescope is composed of a nested array of 12 mirrors with an aperture of 0.3 m and a focal length of 3.5 m. The mirror shells have Wolter I geometry and are replicated by an electroforming process for which Carl Zeiss manufactured the 12 monolithic Nickel coated aluminum mandrels. In order to determine the mandrel limited HEW, several measurement and analysis steps including raytracing calculations are performed. The major contributions to the error budget, axial slopes and roundness errors, as well as the position of the focus are investigated. The results are reported and discussed.

The Coronal Diagnostic Spectrometer (CDS) is one of the key-instruments on the ESA-cornerstone mission SOHO, scheduled for launch in 1995. It is designed to study the solar corona in the EUV. The engineering model (EM) of the Wolter-Schwarzschild-II entrance optics of the spectrometer has been manufactured and assembled at Carl Zeiss. The on-axis resolution of the system is specified to 2 arcsec half-energy-width which sets very stringent limits on the figuring and alignment tolerances. In connection with the rather large sagittal depths of the generatingprofiles, the strong curvature differences and the overall geometric dimensions very high demands had to be set onthe fabrication-, metrology- and assembly-techniques, e.g. : Computer controlled polishing was used to finish theprimary mirror; a contour-line-measuring device with 1.25 nm resolution and a dynamical range of several mm hadto be developed; a dedicated assembly set-up allows for mirror-movements in the range of 5Onm, necessary for thealignment in connection with a sufficient stiffness during the glueing of the system.

XMM is a highly nested (58 individual shells) Wolter-I type X-ray telescope with a focal length of 7.5 m. The specified resolution (HEW) is 30 (goal 20) arcsec. In order to qualify single mirror shells and align and assemble the whole mirror module in a reasonable time it is inevitable to apply fast test and strongly converging alignment procedures. By means of two scanning laser beams intra- and extrafocal images of two mirror shells will be registered on a CCD-camera coupled to an image processing PC. One of the mirrors is already glued and serves as a reference while the second one has to be aligned yet. From the data axial and lateral focus positions as well as focus dimensions are calculated. A feed back loop then activates a set of actuators coupled to the mirror to be aligned. In an iterative way the alignment status of this mirror will be optimized. Finally, this mirror is cemented under optical control. First results from a basic test setup with only one mirror will be presented.