Measurement of the refractive-index structure constant,C2n, and its profile in the ground level atmosphere by moiré technique

Saifollah Rasouli; Mohammad Taghi Tavassoly

doi:10.1117/12.683873

28 September 2006 Measurement of the refractive-index structure constant, C_n², and its profile in the ground level atmosphere by moire technique

Saifollah Rasouli, Mohammad Taghi Tavassoly

Author Affiliations +

Proceedings Volume 6364, Optics in Atmospheric Propagation and Adaptive Systems IX; 63640G (2006) https://doi.org/10.1117/12.683873
Event: SPIE Remote Sensing, 2006, Stockholm, Sweden

Abstract

Atmospheric turbulence may have strong impact on astronomical imaging, aerial surveying, terrestrial geodesy, optical ranging, and wireless optical communication. Major effects are beam broadening, irradiance fluctuations (scintillation), and angle-of-arrival (AA) fluctuations. The interesting effects of atmospheric turbulence for optical propagation studies are the variation (gradient and fluctuations) of refractive index. The corresponding refractive- index structure constant, C_n², is the parameter most commonly used to describe the strength of atmospheric turbulence. Besides, the Modulation Transfer Function of the atmosphere is measurable by C_n². Good image quality requires C_n² being as small as possible. In this work we present an easily applicable and accurate method, based on moire technique, for the measurement of C_n² and its profile in the ground level atmosphere. In this method from a low frequency sinusoidal amplitude grating, installed at certain distance from a telescope, successive images are recorded and stored in a computer. By rotating one of the image by +θ, say 4°, and multiplying its transmission function by the transmission functions of the other images which have been rotated by -θ, a large number of moire patterns are produced. By finding the traces of the moire fringes in the patterns, the fluctuations of the image grating lines are obtained. Which correspond to AA fluctuations distribution. From the AA fluctuations distribution in successive patterns, C_n² and its profile in vertical direction are deduced. This technique renders to measure some other atmospheric parameters which are discussed in the report.

Citation Download Citation

Saifollah Rasouli and Mohammad Taghi Tavassoly "Measurement of the refractive-index structure constant, C_n², and its profile in the ground level atmosphere by moire technique", Proc. SPIE 6364, Optics in Atmospheric Propagation and Adaptive Systems IX, 63640G (28 September 2006); https://doi.org/10.1117/12.683873

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