Measurements of Scattered Light from Mirrors and Lenses

Hostetter, G. R.; Pätz, Daniel; Hill, H. A.; Zanoni, C. A.

doi:10.1364/ao.7.001383

Cited by 9 publications

(2 citation statements)

References 6 publications

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“…Lens a is the best lens of a set described in Leinert and Kluppelberg. 16 The lens b results were presented by Hostetter et al 14 This lens was of ''coronagraph quality.'' The lens c results were taken from the data presented by Smartt 15 and represent the average of two ''coronagraph quality'' lenses.…”

Section: Implications Of the Visible Scattered Light Measurements Formentioning

confidence: 98%

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Measurement of near‐specular visible‐wavelength scattered light from two superpolished ‘‘coronagraph quality’’ mirrors

et al. 1996

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Several coronagraphs with mirror objectives are planned or have been constructed for terrestrial and space-based observatories. To justify the nontraditional choice of an internally occulted, reflective design for the inner coronal channel of the large-angle spectrometric coronagraph (LASCO) instrument constructed for the Solar Heliospheric Observatory satellite, we measured the near-specular (0.09 to 1.25 deg) scatter of two superpolished, spherical coronagraph mirrors with a unique geometry scatterometer. The visible stray light emanating from defectfree portions of the best mirror was measured to be 3.5ϫ10 Ϫ7 B/B ᭪ (coronal brightness relative to the mean solar brightness) at 2R ᭪ (heliocentric distance in solar radii) and 2ϫ10 Ϫ7 B/B ᭪ at 3R ᭪ . These levels are well below typical sky brightnesses of ϳ10 Ϫ5 B/B ᭪ present at mountaintop observatories with clear skies. This stray light level would allow spectroscopic differencing observations of visible coronal emission lines (ϳ4ϫ10 Ϫ8 B/B ᭪ at 2R ᭪ for coronal green line features) well into the inner corona from a space-based platform. An aspheric mirror with better performance than this stray light has been installed in the LASCO flight instrument. We describe the scatterometer apparatus, detail the experimental results, and present a comparison between predicted coronagraph stray light levels and nominal coronal signal levels. © 1996 Society of Photo-Optical Instrumentation Engineers.

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Section: Implications Of the Visible Scattered Light Measurements Formentioning

confidence: 98%

“…Mirror a was the best mirror measured by Leinert and Kluppelberg. 16 Mirror b was a ''coronagraph quality'' superpolished flat mirror measured by Hostetter et al 14 Mirror c was the average of three mirrors measured by Smartt. 15 These mirrors were fabricated for use in a balloon-borne, infared externally occulted coronagraph.…”

Section: Figmentioning

confidence: 99%