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Proceedings Paper

Fabricating subcollimating grids for an x-ray solar imaging spectrometer using LIGA techniques
Author(s): Reid A. Brennen; Michael H. Hecht; Dean V. Wiberg; Steven Manion; William D. Bonivert; Jill M. Hruby; Marcus L. Scholz; Timothy D. Stowe; Thomas W. Kenny; Keith H. Jackson; Chantal G. Khan Malek
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Paper Abstract

We are fabricating sub-collimating X-ray grids that are to be used in an instrument for the High Energy Solar Spectroscopic Imager (HESSI), a proposed NASA mission. The HESSI instrument consists of twelve rotating pairs of high aspect ratio, high Z grids, each pair of which is separated by 1.7 meters and backed by a single Ge detector. The pitch for these grid pairs ranges from 34 micrometers to 317 micrometers with the grid slit openings being 60% of the pitch. For maximum grid X-ray absorbing with minimum loss of the solar image, the grid thickness-to-grid-slit ratio must be approximately 50:1, resulting in grid thicknesses of 1 to 10 millimeters. For our proof-of-concept grids we are implementing a design in which a 34 micrometers pitch, free-standing PMMA grid is fabricated with 20 micrometers wide slits and an 800 micrometers thickness. Stiffeners that run perpendicular to the grid are placed every 500 micrometers . After exposure and developing, metal, ideally gold, is electrodeposited into the free-standing PMMA grid slits. The PMMA is not removed and the metal in the slits acts as the X-ray absorber grid while the PMMA holds the individual metal pieces in place, the PMMA being nearly transparent to the X-rays coming from the sun. For optimum imaging performance, the root-mean-square pitch of the two grids of each pair must match to within 1 part in 10000 and simultaneous exposures of stacked sheets of PMMA have insured that this requirement is met.

Paper Details

Date Published: 26 September 1995
PDF: 12 pages
Proc. SPIE 2640, Microlithography and Metrology in Micromachining, (26 September 1995); doi: 10.1117/12.222650
Show Author Affiliations
Reid A. Brennen, Jet Propulsion Lab. (United States)
Michael H. Hecht, Jet Propulsion Lab. (United States)
Dean V. Wiberg, Jet Propulsion Lab. (United States)
Steven Manion, Jet Propulsion Lab. (United States)
William D. Bonivert, Sandia National Lab. (United States)
Jill M. Hruby, Sandia National Lab. (United States)
Marcus L. Scholz, Stanford Univ. (United States)
Timothy D. Stowe, Stanford Univ. (United States)
Thomas W. Kenny, Stanford Univ. (United States)
Keith H. Jackson, Lawrence Berkeley National Lab. (United States)
Chantal G. Khan Malek, Louisiana State Univ. (United States)

Published in SPIE Proceedings Vol. 2640:
Microlithography and Metrology in Micromachining
Michael T. Postek, Editor(s)

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