Demonstration of a portable system for daytime optical turbulence profile measurements

Abstract

ABSTRACT Measurements of the optical turbulence profile are critical for selecting a potential new solar observational site or for characterizing an existing solar observatory. To measure the turbulence distribution to a moderate altitude above an existing observatory, current techniques use a large facility telescope with an aperture size larger than 1.0 m. This limits their application, especially in surveys to find a new potential site where no large facility telescope is available and where a portable measurement device is needed for such measurements. To address the above issues, we propose a new technique, termed the Advanced Multiple Aperture Seeing Profiler (A-MASP), which uses solar granulation to measure the daytime optical turbulence profile. The A-MASP is a portable system and thus can fully address the fundamental limitation of current optical turbulence profile measurement techniques. The A-MASP consists of two small telescopes, each with an aperture of the order of 100 mm, which can measure the turbulence profile to an altitude up to 20 km. Here, we present our A-MASP development work and its initial on-site measurements at the Big Bear Solar Observatory. In a proof-of-concept experiment, it was successfully demonstrated that the A-MASP can reliably measure the turbulence profile up to 12 km with a vector separation of 0.7 m between the two telescopes. The A-MASP could be used for future surveys to find potentially good observational sites.