Recently there has been resurging interest in beryllium telescopes ranging in aperture from 0.25-1.5 meter for various NASA space missions. The central theme for this discussion is axially symmetric, all beryllium telescope design forms that are part of advanced LIDAR altimetry systems used to measure the topography and relative density of surface and atmospheric features on the earth and on other planetary bodies. Similar NASA LIDAR missions have previously been sent to Earth’s orbit, the Moon, Mars, and are under consideration for other surveys within the solar system. Design considerations include achieving minimized mass simultaneous with demanding structural, thermal, and optical requirements on orbit after sustaining the rigors of space launch. Modern analysis tools and modeling techniques enable simulation of telescope wavefront errors resulting from environmental effects and the influences of bi-metallic bending from platings. Manufacturing considerations include progressive machining, diamond point turning, coordinate measurement machine profilometry, computerized grinding and polishing, brazing of complex beryllium structures, very thin electroless nickel plating, and other advanced manufacturing technologies imperative to successful visible–infrared optical performance. Recent design and manufacturing efforts on 0.60, 0.80, and 1.0 meter beryllium telescopes are profiled to illustrate the confluence of applicable design and manufacturing technologies.
An optical system capable of extremely high contrast imaging (about 10-10) at separations comparable to the
telescope's diffraction limit is critical for direct imaging of extrasolar terrestrial planets. The PIAA coronagraph
(Guyon 2003) based on pupil apodization by geometrical remapping of the flux in the pupil plane seems to be
especially adopted for the exoplanet imaging. Although this technique combines many of the advantages found
separately in other coronagraphs, two serious concerns remain unanswered: optics manufacturability and effects
of diffraction propagation. We describe here a hybrid PIAA/CPA (Classical Pupil Apodization) design in which
the apodization is shared between a remapping system (the main apodizer) and "classical" apodizers (auxillary
apodizers). In this scheme, optics become easier to manufacture and diffraction effects can be decreased to a
level consistent with a 10-10 PSF contrast in a wide spectral band. We show how the parameters of hybrid
PIAA/CPA system can be optimized and present some results of optical testing for the high optical quality
prototype of PIAA coronagraph.