Share Email Print
cover

Proceedings Paper

Corrals, hubcaps, and crystal balls: some new designs for very-wide-angle visible-light heliospheric imagers
Author(s): Andrew Buffington; Pierre Paul Hick; Bernard V. Jackson; Clarence M. Korendyke
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Emerging techniques allow instruments to view very large sky areas, a hemisphere or more, in visible light. In space, such wide-angle coverage enables observation of heliospheric features form close to the Sun to well beyond Earth. Observations from deep-space missions such as Solar Probe, Stereo, and Solar Polar Sail, coupled with observations near Earth, permit 3D reconstruction of solar mass ejections and co-rotating structures, discovery and study of new comets and asteroids, and detailed measurements of brightness variations in the zodiacal cloud. Typical heliospheric features have 1 percent or less of ambient brightness, so visible-light cameras must deliver < 0.1 percent photometry and be well protected from stray background light. When more than a hemisphere of viewing area is free of bright background-light sources, we have shown that corral-like structures with several vane-like walls reduces background light illuminating to wide-angle optical system by up to ten orders of magnitude. The optical system itself typically provides another five orders of surface-brightness reduction. With CCDs as the light-detection device, images of point-like sources must cover typically 100 pixels to average down sub-pixel response gradients and provide the above 0.1 percent photometry. With present-day CCDs this requires images of order 1 degree in angular size. Tolerating such large images in turn enables wide-angle sky coverage using simple reflecting and refracting optical systems such as convex spherical reflectors, toroids and thick lenses. We show that combining these with light- reducing corrals yields practical, light-weight instruments suitable for inclusion on deep-space probes.

Paper Details

Date Published: 2 November 1998
PDF: 10 pages
Proc. SPIE 3442, Missions to the Sun II, (2 November 1998); doi: 10.1117/12.330266
Show Author Affiliations
Andrew Buffington, Univ. of California/San Diego (United States)
Pierre Paul Hick, Univ. of California/San Diego (United States)
Bernard V. Jackson, Univ. of California/San Diego (United States)
Clarence M. Korendyke, Naval Research Lab. (United States)


Published in SPIE Proceedings Vol. 3442:
Missions to the Sun II
Clarence M. Korendyke, Editor(s)

© SPIE. Terms of Use
Back to Top