Engineering topics

Zissa, D. E.

Publications and source records attributed to Zissa, D. E..

5 records

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 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 NTRS1984

Signal-to-noise ratio for the wide field-planetary camera of the Space Telescope

Signal-to-noise ratios for the Wide Field Camera and Planetary Camera of the Space Telescope were calculated as a function of integration time. Models of the optical systems and CCD detector arrays were used with a 27th visual magnitude point source and a 25th visual magnitude per arc-sq. second extended source. A 23rd visual magnitude per arc-sq. second background was assumed. The models predicted signal-to-noise ratios of 10 within 4 hours for the point source centered on a signal pixel. Signal-to-noise ratios approaching 10 are estimated for approximately 0.25 x 0.25 arc-second areas within the extended source after 10 hours integration.

Zissa, D. E.↗

NASA NTRS1984

Optical contacting for gravity probe star tracker

A star-tracker telescope, constructed entirely of fused silica elements optically contacted together, has been proposed to provide submilliarc-second pointing accuracy for Gravity Probe. A bibliography and discussion on optical contacting (the bonding of very flat, highly polished surfaces without the use of adhesives) are presented. Then results from preliminary experiments on the strength of optical contacts including a tensile strength test in liquid helium are discussed. Suggestions are made for further study to verify an optical contacting method for the Gravity Probe star-tracker telescope.

Wright, J. J.↗

NASA NTRS1984

Optical analysis of the star-tracker telescope for Gravity Probe

A ray tracing modeling of the star tracker telescope for Gravity Probe was used to predict the character of the output signal and its sensitivity to fabrication errors. In particular, the impact of the optical subsystem on the requirement of 1 milliarc second signal linearity over a + or - 50 milliarc second range was examined. Photomultiplier and solid state detector options were considered. Recommendations are made.

Zissa, D. E.↗