Analysis And Implementation Of Non-Kolmogorov Phase Screens Appropriate To Structured Environments

Goldring, Thomas; Carlson, L. W.

doi:10.1117/12.951750

Cited by 12 publications

(11 citation statements)

References 6 publications

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“…The phase distribution can be derived from the power spectrum by using the method reported in Ref. 7. With a little difference in the notation and expression, the phase distribution derived by using that method is…”

Section: Generating Irregular Phase Distributionsmentioning

confidence: 99%

Turbulence simulation plate based on irregular micro-optical structures fabricated by a mask-moving technique

et al. 2008

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A laboratory turbulence simulation based on irregular microoptical structures has been studied. The phase distributions are derived from Kolmogorov spectra with different Fried parameters r 0 by using the fast Fourier transform technique. A mask-shifting method has been invented for generating the designed irregular phase on a quartz substrate. The fabricated element is rotated by a motor to construct a turbulence generator. The dynamic phase produced by the generator is measured in real time with Shack-Hartmann sensor. The resulting power spectrum and the Fried parameter agree with the expected ones. Some issues associated with the simulation of turbulence are discussed.

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Section: Generating Irregular Phase Distributionsmentioning

confidence: 99%

Turbulence simulation plate based on irregular micro-optical structures fabricated by a mask-moving technique

et al. 2008

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“…A full two transverse dimensional model is in the process of development and will be reported on in the near future. For propagation through a medium with constant index of refraction n and any given initial beam, one solves the paraxial equation 0' 82, 2ik-+ -i + k2(n2 -1)t,h = 0 (8) äz äx where 1/) is a complex amplitude representing the beam, z is the direction of propagation, 2; 15 the transverse direction, and k = 2ir/A for A the wavelength. This can be efficiently computed for a propagation step z z z0 + Ez using a pseudospectral method.…”

Section: Variance Of the Index Of Refractionmentioning

confidence: 99%

“…Along with (4), (5), and (7) we construct the following The propagation of a laser beam through a disturbed environment is simulated using the well known "multiple phase screen" approach which will be briefly described here in the case of one transverse dimension (but see [8] for a more complete exposition) . A full two transverse dimensional model is in the process of development and will be reported on in the near future.…”

Section: Variance Of the Index Of Refractionmentioning

confidence: 99%

Propagation studies in a disturbed ionospheric environment

Huba

Goldring

1990

SPIE Proceedings

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“…The phase screens were generated using a white noise filtering approach [19,20,30,31]. Phase screens possessing the von Karman spectrum with outer scale Lo = 100 m were simulated using this method so that ensemble of phase screens has the power spectrum 0.00969ft,C;…”

Section: Simulation Descriptionmentioning

confidence: 99%

“…The phase screens were created in 2N x 2N arrays, and the center N x N section was extracted to avoid problems arising from the fact that autocorrelation of the phase is an even function [31]. While this approach to phase screen generation has been widely used [19,20,30,31,32], this approach is known to produce phase screens which are affected by truncation of the power spectrum at both high spatial frequencies, due to finite sample spacing Aa;, and at low spatial frequencies, due to finite array size N. We adopt this phase screen generation technique here because of its speed of operation, and because of reasonable agreement between theory and simulation [19].…”

Section: Simulation Descriptionmentioning

confidence: 99%

Scintillation Control for Adaptive Optical Sensors

Roggemann¹

1999

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Public Reporting burden for this collection of information is estimated to average 1 hour per response, including the time and maintaining the data needed, and completing and reviewing the collection of information. Send comment regarding information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for infom 1204, Arlington, VA 22202-4302, and Michigan Technological University (MTU) has been investigating strategies for overcoming the effects of scintillation on adaptive optical imaging and laser beam projection systems which must operate in the presence of extended path turbulence. The approach originally proposed under this contract involved using two deformable mirrors to fully conjugate the received or transmitted beam. Our investigations into this concept have shown that implementation details associated with the use of real adaptive optical hardware will likely limit the effectiveness of the two deformable mirror technique. As a consequence, an alternative approach using one deformable mirror was developed, and its performance was investigated. This technique exploits the fact that, under strong scintillation conditions, information about the phase of the beacon field is incorporated in the intensity of the beacon field. Hence, deformable mirror commands which are consistent with all of the intensity measurements available to an adaptive optical system are processed using a new nonlinear optimization-based algorithm. Our studies of the performance of this technique have shown that under conditions of saturated scintillation this new approach significantly outperforms the standard centroid-based processing of the Hartmann sensor measurements. An experiment conducted at MTU has demonstrated the ability to predict a laser intensity pattern in a distant target plane using Hartmann sensor measurements of the field reflected from a deformable mirror. One accepted journal article, and one submitted journal article have resulted from this work, along with three conference papers. In addition, this work forms the basis of a program which is now being conducted with the Airborne Laser Technology Division. that implementation details associated with the use of real adaptive optical hardware will likely limit the effectiveness of the two deformable mirror technique. As a consequence, an alternative approach using one deformable mirror was developed, and its performance was investigated. This technique exploits the fact that, under strong scintillation conditions, information about the phase of the beacon field is incorporated in the intensity of the beacon field. Hence, deformable mirror commands which are consistent with all of the intensity measurements available to an adaptive optical system are processed using a new nonlinear optimization-based algorithm. Our studies of the performance of this technique have shown that under conditions of saturated scintillation this new approach significantly outperforms the standard centroid-based processing of the Hartmann sen...

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Analysis And Implementation Of Non-Kolmogorov Phase Screens Appropriate To Structured Environments

Cited by 12 publications

References 6 publications

Turbulence simulation plate based on irregular micro-optical structures fabricated by a mask-moving technique

Turbulence simulation plate based on irregular micro-optical structures fabricated by a mask-moving technique

Propagation studies in a disturbed ionospheric environment

Scintillation Control for Adaptive Optical Sensors

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