T. Hadjimichael

Design and fabrication of refractive nulls for testing the segmented mirrors of the Constellation-X spectroscopy x-ray telescope (SXT)

We designed a refractive null lens for (visible) optical testing of the segmented mirrors for the Constellation-X spectroscopy x-ray telescope. We explored two solution families and identified the trade-offs. We also present some initial results of the realization of one solution family.

Toward a complete metrologic solution for the mirrors for the Constellation-X Spectroscopy x-ray telescope

We present an overview update of the metrologic approach to be employed for the segmented mirror fabrication for Constellation-X spectroscopy x-ray telescope. We compare results achieved to date with mission requirements. This is discussed in terms of inherent capability versus in-practice capability. We find that all the needed metrics for the mirrors are in hand but that they are currently limited by the mounting of the mirrors themselves.

Testing of the mirrors for the Constellation-X spectroscopy x-ray telescope with a refractive null

We present an introduction to the use of a refractive null lens for testing grazing incidence x-ray mirrors for the Constellation-X mission. The singular role of mirror mounting in glass shell mirror metrology is also touched upon. We compare results achieved to date with mission requirements along with some of the unique properties of the null lens. Additionally, uses beyond mirror metrology are briefly discussed.

Progress toward a complete metrology set for the International X-ray Observatory (IXO) soft x-ray mirrors

We present an overview update of the metrologic approach to be employed for the segmented mirror fabrication for the IXO soft x-ray telescope. We compare results achieved to date with mission requirements. This is discussed in terms of inherent capability versus in-practice capability. We find that all the needed metrology equipment are in hand but that a number of the needed quantities remain too uncertain relative to mission requirements. This is driven by the mounting of the mirrors themselves. We then discuss some plans for addressing the mirror mounting issues. Finally, we also briefly discuss some promising mandrel metrology techniques.

Cryogenic metrology for the James Webb Space Telescope Integrated Science Instrument Module alignment target fixtures using laser radar through a chamber window

The James Webb Space Telescope Integrated Science Instrument Module utilizes two fixtures to align the Optical Telescope Element Simulator (OSIM) to the coordinate systems established on the ISIM and the ISIM Test Platform (ITP). These fixtures contain targets which are visible to the OSIM Alignment Diagnostics Module (ADM). Requirements on these fixtures must be met under ambient and cryogenic conditions. This paper discusses the cryogenic metrology involving Laser Radar measurements through a chamber window that will be used to link photogrammetry target measurements used during ISIM structure cryogenic verification and the ADM targets, including evaluation of distortion introduced from the window.

An alignment procedure for multi-element precision cylinder lenses and modular enclosure to house them

We present a method for the precision alignment of cylinder lenses which has been employed for the null lenses used to test the segmented mirrors for the IXO x-ray telescope. We also present a design for a housing for such a lens.

Large volume, optical and opto-mechanical metrology techniques for ISIM on JWST

The final, flight build of the Integrated Science Instrument Module (ISIM) element of the James Webb Space Telescope is the culmination of years of work across many disciplines and partners. This paper covers the large volume, ambient, optical and opto-mechanical metrology techniques used to verify the mechanical integration of the flight instruments in ISIM, including optical pupil alignment. We present an overview of ISIMs integration and test program, which is in progress, with an emphasis on alignment and optical performance verification. This work is performed at NASA Goddard Space Flight Center, in close collaboration with the European Space Agency, the Canadian Space Agency, and the Mid-Infrared Instrument European Consortium.

Ambient optomechanical alignment and pupil metrology for the flight instruments aboard the James Webb Space Telescope

While efforts within the optics community focus on the development of high-quality systems and data products, comparatively little attention is paid to their use. Our standards for verification and validation are high; but in some user domains, standards are either lax or do not exist at all. In forensic imagery analysis, for example, standards exist to judge image quality, but do not exist to judge the quality of an analysis. In litigation, a high quality analysis is by default the one performed by the victorious attorney’s expert. This paper argues for the need to extend quality standards into the domain of imagery analysis, which is expected to increase in national visibility and significance with the increasing deployment of unmanned aerial vehicle—UAV, or “drone”—sensors in the continental U. S.. It argues that like a good radiometric calibration, made as independent of the calibrated instrument as possible, a good analysis should be subject to standards the most basic of which is the separation of issues of scientific fact from analysis results.

Constellation-X Mirror Technology Development

As NASAs next major space X-ray observatory, the Constellation-X mission (Bookbinder et al. 2008) requires mirror assemblies with unprecedented characteristics that cannot be provided by existing optical technologies. In the past several years, the project has supported a vigorous mirror technology development program. This program includes the fabrication of lightweight mirror segments by slumping commercially available thin glass sheets, the support and mounting of these thin mirror segments for accurate metrology, the mounting and attachment of these mirror segments for the purpose of X-ray tests, and development of methods for aligning and integrating these mirror segments into mirror assemblies. This paper describes our efforts and developments in these areas.

Simple method of aligning cylindrical air-spaced elements

A simple method is found to align multielement cylindrical lenses. The method employs only equipment found in most optical shops: a precision flat mirror and a Fizeau interferometer. A combination of narrow reflection in- terferograms from the lens surfaces, combined with cat-eye double-pass interferograms, is employed to align the elements.