Isoplanatic patch considerations for solar telescope multi-conjugate adaptive optics

Jacques Maurice Beckers

doi:10.1117/12.2055348

13 August 2014 Isoplanatic patch considerations for solar telescope multi-conjugate adaptive optics

Jacques Maurice Beckers

Proceedings Volume 9148, Adaptive Optics Systems IV; 914860 (2014) https://doi.org/10.1117/12.2055348
Event: SPIE Astronomical Telescopes + Instrumentation, 2014, Montréal, Quebec, Canada

Abstract

I compare recent site surveys for the future large 4-meter solar and 30-meter nighttime telescopes at the nearby Haleakala and Mauna Kea sites respectively. They show that the outstanding early morning image quality at the solar site corresponds indeed to that observed at the late night one at the nighttime site. That confirms the notion that daytime solar site heating only shows itself later in the morning. The nighttime survey includes observations of the refractive index structure function C_n ²(h) to high altitudes from which the radius of the isoplanatic patch (Ɵ₀) can be determined. At zenith (ζ = 0⁰) it equals 2.5 arcsec at 500 nm wavelength. For the early morning (best) seeing at the solar site, which occurs at ζ_sun = 75⁰ and the cos^1.6(ζ) dependence of Θ₀,that means an extremely small Ɵ₀ (0.26 arcsec). Such small values compromise Adaptive Optics (AO) solar correlation wavefront sensing for which areas are needed equal to about 8”× 8” I suggest options for measuring C_n²(h), and therefore Ɵ₀, during the day. These make use of the solar image as well as of daytime images of bright stars and planets. Some use the MASS technique on stars; some use the SHABAR technique using very large detector baselines on the Sun and shorter baselines on planets. It is suggested that these C_n²(h) measurements are made also during regular solar observations. In that way optimal solar observations can be planned using real-time Ɵ₀ observations by image selection and optimization of the MCAO configuration.

Citation Download Citation

Jacques Maurice Beckers "Isoplanatic patch considerations for solar telescope multi-conjugate adaptive optics", Proc. SPIE 9148, Adaptive Optics Systems IV, 914860 (13 August 2014); https://doi.org/10.1117/12.2055348

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available