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Korsch, D.

Publications and source records attributed to Korsch, D..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Experimental evaluation of the ring focus test for X-ray telescopes using AXAF's technology mirror assembly, MSFC CDDF Project No. H20

A test method particularly suited for X-ray telescopes was evaluated experimentally. The method makes use of a focused ring formed by an annular aperture when using a point source at a finite distance. This would supplement measurements of the best focus image which is blurred when the test source is at a finite distance. The telescope used was the Technology Mirror Assembly of the Advanced X-ray Astrophysis Facility (AXAF) program. Observed ring image defects could be related to the azimuthal location of their sources in the telescope even though in this case the predicted sharp ring was obscured by scattering, finite source size, and residual figure errors.

Zissa, D. E.↗
NASA NTRS1986

Comparison of large aperture telescopes with parabolic and spherical primaries

Quasi-Cassegrain-type four-mirror telescopes are compared to conventional two-mirror Cassegrain telescopes for use as high performance, very large aperture space telescopes. Spherical and parabolic primaries with continuous as well as segmented surfaces are considered. Imaging characteristics and misalignment sensitivities serve as the principal criteria of comparison. The evaluation shows that parabolic primaries yield superior wide-field performance, whereas spherical primaries hold distinct advantages regarding manufacturability and regarding certain alignment aspects in the case of segmentation.

Korsch, D.↗
NASA NTRS1986

Test Method for X-Ray Telescopes

Telescopes and X-ray telescopes in particular, tested with nearby point sources of radiation. When point-source rays enter telescope through annular entrance pupil (and under conditions of spherical aberration), ring image produced. Deviation of ring image from perfect circular shape reveals misalinements and surface inaccuracies in telescope. Although particularly suited for grazing-incidence types of systems, this test method applied to other types of optical systems.

Korsch, D.↗
NASA NTRS1985

An optical technology study on large aperture telescopes

The difficult and crucial problem of selecting a suitable telescope concept for an advanced space observatory was examined. To this end two and four mirror telescopes were analyzed and compared. Both configurations are very practical and structurally similar. Parabolic primary and spherical primary four mirror telescope were compared with respect to their performance and the alignment sensitivities of the three correction mirrors. A 1 meter class afocal telescope system with lag angle compensation, to be used in a LIDAR experiment, was examined.

Korsch, D.↗
NASA NTRS1985

Test method for telescopes using a point source at a finite distance

A test method for telescopes that makes use of a focused ring formed by an annular aperture when using a point source at a finite distance is evaluated theoretically and experimentally. The results show that the concept can be applied to near-normal, as well as grazing incidence. It is particularly suited for X-ray telescopes because of their intrinsically narrow annular apertures, and because of the largely reduced diffraction effects.

Griner, D. B.↗
NASA NTRS1985

Nearly Anastigmatic X-Ray Telescope

Proposed X-ray telescope made of many concentric reflecting rings, each of which consists of two portions of cone. Proposed design is variation on conventional grazing incidence X-ray telescope, which has just one twosegment reflecting element but suffers from excessive astigmatism and field curvature. Using many short elements instead of single long element, new design gives nearly anastigmatic image.

Korsch, D.↗
NASA NTRS1984

Coherent optical system of modular imaging collectors (COSMIC) - An approach for a large aperture high angular resolution telescope in space

Very high angular resolution can be achieved in UV/optical astronomy through interferometers in space. A concept analysis of COSMIC, which may be placed into orbit by the Space Shuttle in the late 1990's, is discussed. The photon-collecting area is three times larger than that of Space Telescope (ST), and exceeds its resolution by approximately an order of magnitude. Several alternative configurations are presented to scope the extent of design approaches which may be achievable within the transportation capability of the Space Shuttle.

Davis, B.↗
NASA NTRS1984

Near anastigmatic grazing incidence telescope

A performance capability assessment is presently conducted for short versus long grazing incidence telescope designs, in view of the observation that the field curvature and astigmatism that are the primary residual aberrations of a Wolter-type incidence telescope can be substantially reduced through mirror length reduction. A major advantage of the short element telescope is that, if sufficiently short, both the paraboloid and hyperboloid surfaces may be fabricated as a single piece; this significantly facilitates the task of alignment.

Korsch, D.↗
NASA NTRS1980

Error budget analysis for advanced X-ray Astrophysics Facility (AXAF)

The AXAF telescope was analytically investigated during the period from September 1979 to March 1980. The results of a performance evaluation in the presence of aligment errors and surface defects, a sensitivity analysis of every individual subsystem, and a diffraction analysis of the telescope assembly are presented.

Korsch, D.↗
NASA NTRS1980

Super-size space telescope

A class of space telescopes for astronomical observations with a resolution and collecting capability more than one order of magnitude better than what is expected from the 2.4 m Space Telescope is discussed. To this purpose aplanatic two-mirror systems of coplanar primary/secondary mirror arrangements with approximately 45 deg angles of incidence and an overall diameter of about 100 m have been designed and analyzed. The main advantages of these systems are their compactness and the associated minimization of the moment of inertia in two axes. Two opposing secondary arrangements, one forward-reflecting and the other backward-reflecting are analyzed and compared.

Korsch, D.↗
NASA NTRS1979

AXAF optical technology analysis

A grazing incidence telescope with six nested subsystems is investigated through the effects of misalignment and surface deformations on it's image quality. The axial rms-spot size serves as measure for the image quality. The surface deformations are simulated by ellipsoidal and sinusoidal deviation elements. Each type of defect is analyzed in the single two-element system. The full nested system is then analyzed in the presence of all possible defects on all twelve elements, whereby the magnitude of the defects is randomized within a given upper limit.

Korsch, D.↗
NASA NTRS1979

Influence of alignment and surface defects on the performance of X-ray telescopes

The effects of misalignment and surface deformations on the image quality of a grazing incidence telescope with six nested subsystems are investigated. The axial rms-spot size serves as a measure for the image quality. The surface deformations are simulated by ellipsoidal and sinusoidal deviations from the ideal surface. Misalignments are tilts, decenters, and despaces of the individual elements. The effects of each type of defect are analyzed in a single two-element system. The full nested system is then analyzed in the presence of all possible defects on all 12 elements, whereby the magnitude of the defects is randomized within a given upper limit.

Korsch, D.↗
NASA NTRS1979

Design of stigmatic grazing incidence telescopes with non-parabolic primaries

A two-mirror grazing-incidence telescope having a non-parabolic primary, and designed to be free of spherical aberration has been investigated. A method for determining the second surface equation is described, when the surface equation for one mirror is given. Application to grazing incidence systems such as used in X-ray and planed for EUV astronomy is discussed. Of special interest is the design of a secondary mirror when the hyperboloid of a conventional Wolter type I system is taken as the primary.

Winkler, C. E.↗
NASA NTRS1978

Three-mirror space telescope, volume 2

The anastigmatic three mirror telescope for STARSAT, a space astronomy facility, was redesigned and reoptimized in order to improve the optical system and increase its versatility. A more compact system was obtained by decreasing the primary focal ratio from 2.2 to 2.0. A high performance Rowland spectrograph that uses only a total of three reflections and does not interfere with the imaging process, was successfully incorporated into the telescope so that it could be a permanent part of the system. The usefulness of this telescope concept as a high resolution coronagraph is examined.

Korsch, D.↗
NASA NTRS1977

Performance analysis of grazing incidence imaging systems

An exact expression relating the coordinates of a point on the incident ray, a point of reflection from an arbitrary surface, and a point on the reflected ray is derived. The exact relation is then specialized for the case of grazing incidence, and first order and third order systematic analyses are carried out for a single reflective surface and then for a combination of two surfaces. The third order treatment yields a complete set of primary aberrations for single element and two element systems. The importance of a judicious choice for a coordinate system in showing field curvature to clearly be the predominant aberration for a two element system is discussed. The validity of the theory is verified through comparisons with the exact ray trace results for the case of the telescope.

Winkler, C. E.↗
NASA NTRS1977

Primary aberrations for grazing incidence

Beginning with exact relations between object and image coordinates for a single reflective surface, a systematic analysis of general grazing incidence systems is presented. A complete set of primary aberrations for single-element and two-element systems is developed. The importance of a judicious choice for a coordinate system in showing field curvature to be clearly the predominant aberration for a two-element system is discussed. The validity of the theory is verified through comparisons with the exact ray-trace results for the case of a telescope.

Winkler, C. E.↗
NASA NTRS1977

Anastigmatic three-mirror telescope

A three-mirror telescope arrangement that can be corrected for four aberrations (coma, spherical aberration, field curvature, and astigmatism) is described. Geometric spot size is less than 0.1 sec of arc, in an easily accessible flat field of 1.5 deg. The primary-secondary configuration is Cassegrain-like, with the real image formed closely behind the primary. This secondary image is re-imaged by a tertiary mirror at roughly unit magnification. A small, flat mirror at the exit pupil, located between primary and tertiary, folds the light rectangularly away from the telescope axis. The shape of the large image area is helpful in space applications where several instruments may share the focal plane.

Korsch, D.↗