Optical Performance of Large Ground-based Telescopes

Dierickx, Philippe

doi:10.1080/09500349214550551

Cited by 41 publications

(19 citation statements)

References 3 publications

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“…Following the work of Roddier (1981), the angular size in arcseconds of the FWHM of the images point spread function is given by Dierickx (1992) as:…”

Section: Principles Of Seeing Measurementmentioning

confidence: 99%

Antarctic site testing – microthermal measurements of surface-layer seeing at the South Pole

Marks

Vernin

Azouit

et al. 1996

Astron. Astrophys. Suppl. Ser.

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Abstract. -Results from experiments measuring the optical seeing in the surface layer at the South Pole Station are presented. Seeing measurements were taken over 49 data runs between April and August 1994, using microthermal sensors placed at 3 levels on a 27 m-high mast. The seeing contribution from this region was quite large in comparison with similar experiments performed at other sites, with a mean value measured over this period of 0.64 . However, there is often a significant decrease in the optical turbulence over the height of the mast, with mean values of 0.37 and 0.46 measured in the upper (17−27 m) and lower (7−17 m) sections respectively. These measurements coincide with a large and highly variable temperature inversion, the behaviour of which is often well correlated with the observed turbulence profile. The results can be roughly separated into four or five categories, characterised by the temperature inversion alone. Further analysis of the data should provide some predictive power about the likely optical turbulence profile of the surface layer in given observing conditions.

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“…Following the work of Roddier (1981), the angular size in arcseconds of the FWHM of the images point spread function is given by Dierickx (1992) as:…”

Section: Principles Of Seeing Measurementmentioning

confidence: 99%

Antarctic site testing – microthermal measurements of surface-layer seeing at the South Pole

Marks

Vernin

Azouit

et al. 1996

Astron. Astrophys. Suppl. Ser.

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show abstract

“…The CIR is similar to the Strehl ratio but includes the atmosphere; i.e., it is an intensity-based ratio, defined as the central intensity given by the aberrated telescope divided by the central intensity given by an equivalent perfect telescope [4] . Therefore, the CIR can be denoted as…”

Section: E Relation To Central Intensity Ratiomentioning

confidence: 99%

“…It is so because higher spatial frequency aberrations degrade many types of science more than lower frequency aberrations, even if they both have the same RMS WFE. The CIR [4] was developed to mitigate the problems associated with the larger optical errors of seeing-limited observations. However, as an extension to the Strehl ratio, it considers only the central intensity of the point spread function (PSF); therefore it is also insufficient for describing spatial contributions of telescope aberrations.…”

Section: Introductionmentioning

confidence: 99%

Analysis of normalized point source sensitivity as a performance metric for large telescopes

et al. 2009

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We investigate a new metric, the normalized point source sensitivity (PSSN), for characterizing the seeing-limited performance of large telescopes. As the PSSN metric is directly related to the photometric error of background limited observations, it represents the efficiency loss in telescope observing time. The PSSN metric properly accounts for the optical consequences of wave front spatial frequency distributions due to different error sources, which differentiates from traditional metrics such as the 80% encircled energy diameter and the central intensity ratio. We analytically show that multiplication of individual PSSN values due to individual errors is a good approximation for the total PSSN when various errors are considered simultaneously. We also numerically confirm this feature for Zernike aberrations as well as for the numerous error sources considered in the error budget of the Thirty Meter Telescope (TMT) using a ray optics simulator. Additionally, we discuss other pertinent features of the PSSN, including its relations to Zernike aberration, RMS wave front error, and central intensity ratio.

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“…However, for observations with large ground based telescopes without adaptive optics, where image degradation is dominated by atmospheric seeing, the Strehl Ratio is very small; its measurements and calculations are error prone. To resolve this problem, Dierickx [1] proposed a variant of the Strehl Ratio, called the Central Intensity Ratio (CIR), which is normalized to the PSF of the perfect telescope looking through the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

A convenient telescope performance metric for imaging through turbulence

Angeli

Seo

Nissly

et al. 2011

Optical Modeling and Performance Predictions V

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This paper provides an overview of the various image quality metrics used in astronomical imaging and explains in details a new metric, the Normalized Point Source Sensitivity. It is based on the Equivalent Noise Area concept, an extension of the EE80% metric and is intuitively linked to the required science integration time. As it was proved in recent studies, the PSSN metric properly accounts for image degradation due to the spatial frequency content of a given telescope aberration and the effects of various errors can be multiplicatively combined, like those expressed in Central Intensity Ratio. Extensions of the metric for off-axis imaging and throughput degradation are presented. Wavelength and spatial frequency dependence of PSSN are discussed. While the proper calculation of the PSSN metric requires the precise knowledge of the PSF of both the optics and atmosphere, there is a straightforward approximation linking PSSN to the Zernike decomposition of the OPD. Besides the summary of various aspects of the Point Source Sensitivity, the paper provides many numerical examples derived for the Thirty Meter Telescope.

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Optical Performance of Large Ground-based Telescopes

Cited by 41 publications

References 3 publications

Antarctic site testing – microthermal measurements of surface-layer seeing at the South Pole

Antarctic site testing – microthermal measurements of surface-layer seeing at the South Pole

Analysis of normalized point source sensitivity as a performance metric for large telescopes

A convenient telescope performance metric for imaging through turbulence

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