A liquid crystal atmospheric turbulence simulator

Author(s): Lifa Hu, Li Xuan, Zhaoliang Cao, Quanquan Mu, Dayu Li, and Yonggang Liu

Abstract:

“In the paper, a method to calculate the time evolution turbulence wavefronts based on the covariance method is theoretically presented in detail. According to it, the time-evolution wavefronts disturbed by atmospheric turbulence were experimentally generated by our LC atmospheric turbulence simulator (ATS) based on liquid crystal on silicon (LCOS) with high pixel density, and measured with a wavefront sensor. The advantage of such a LC ATS over a conventional one is that it is flexible with considering the weather parameters of wind speed and Cn², and is relatively easy to control.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 25, pp. 11911-11918 (2006)
DOI: 10.1364/OE.14.011911

Direct measurement of the skew angle of the Poynting vector in a helically phased beam

Author(s): Jonathan Leach, Stephen Keen, Miles J. Padgett, Christopher Saunter, and Gordon D. Love

Abstract:

“We measure the local skew angle of the Poynting vector within a helically-phased, exp (il φ), beam using a Shack Hartmann wavefront sensor. It is the skew angle of the Poynting vector with respect to the beam axis that gives rise to the orbital angular momentum of a light beam. We confirm that this skew angle is l/kr, corresponding to an orbital angular momentum of lћ per photon. Measurement of orbital angular momentum in this way is an alternative to interferometric techniques giving a non-ambiguous result to both the magnitude and sign of l from a single measurement, without any restriction on the optical bandwidth.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 25, pp. 11919-11924 (2006)
DOI: 10.1364/OE.14.011919