Fried’s coherence length measurement of dynamic Kolmogorov type turbulence using autocorrelation function

2021 ◽  
Author(s):  
Lekshmi S S R ◽  
Dinesh Narayana Naik ◽  
C S Narayanamurthy
Keyword(s):  
Autocorrelation Function ◽  
Experimental Verification ◽  
Coherence Length ◽  
Random Phase ◽  
Length Measurement ◽  
Zehnder Interferometer ◽  
Phase Plate ◽  
Kolmogorov Type ◽  
Laboratory Environment ◽  
Quantitative Characteristics

Abstract A new method to find Fried’s coherence length of a dynamic Kolmogorov type turbulence in laboratory environment is reported in this paper. This method utilises autocorrelation function obtained from the quantitative characteristics of a rotating pseudo random phase plate in one of the arms of Mach-Zehnder interferometer. Theoretical formalism and experimental verification are presented.

scholarly journals Beam-smoothing effect in broad-band random-phase irradiation

1993 ◽  
Vol 11 (2) ◽  
pp. 385-390 ◽  
Author(s):  
I. Matsushima ◽  
Y. Owadano ◽  
Y. Matsumoto ◽  
I. Okuda ◽  
T. Tomie ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Optical System ◽  
Random Phase ◽  
Broad Band ◽  
Laser Fusion ◽  
Phase Plate ◽  
Smoothing Effect ◽  
Broad Bandwidth ◽  
A New Technique ◽  
Focusing Lens

A new technique to achieve smooth laser irradiation profiles on laser fusion targets is evaluated numerically and experimentally. In this technique, smoothing is obtained by using a spectral dispersing optic and a random-phase plate placed in front of a focusing lens employing the broad-bandwidth of KrF lasers. Experimental results and numerical calculations agree well, verifying that this simple optical system is effective for smooth irradiation on targets.

Laser wander effect in turbulence simulation system with random phase plate

2011 ◽  
Vol 23 (8) ◽  
pp. 2044-2036
Author(s):  
甘新基 Gan Xinji ◽  
郭劲 Guo Jin ◽  
徐抒岩 Xu Shuyan
Keyword(s):  
Random Phase ◽  
Simulation System ◽  
Phase Plate ◽  
Turbulence Simulation

Design and analysis of a novel random phase plate for uniform illumination

1998 ◽  
Author(s):  
Zengshui Liu ◽  
Runwen Wang ◽  
Huijie Huang ◽  
Dunwu Lu
Keyword(s):  
Random Phase ◽  
Phase Plate ◽  
Uniform Illumination

Broadband Random Phase Diffuser for Ultrasonic Imaging

1979 ◽  
Vol 1 (4) ◽  
pp. 325-332
Author(s):  
Gerard A. Alphonse ◽  
David Vilkomerso
Keyword(s):  
Solid Angle ◽  
Random Phase ◽  
Ultrasonic Imaging ◽  
Standing Waves ◽  
Acoustic Imaging ◽  
Point Sources ◽  
Phase Plate ◽  
Reflected Waves ◽  
Large Aperture ◽  
The Waves

In reflective imaging, waves must be scattered by the object over a broad solid angle so that some of the reflected waves impinge upon the collecting aperture. Surfaces such as biological specimens under study in acoustic imaging are considered smooth at the wavelengths used (e.g., 1 mm) and therefore act as specular reflectors. In order to obtain reflection over a broad spatial range, large aperture, sector or compound scanning are used. In certain types of systems, diffuse insonification is sometimes used by imaging a raster of random phase points onto the surface. However interference between the waves from these point sources produces random fringes or “speckle-like” patterns overlaying the image. In optics these fringes have been reduced by rotating the diffuser. A similar approach has been taken here. This paper describes a simple random phase plate having two levels, 0° and 180 phase that can, by rotation, change the relative phases of the diffuse insonification points so as to reduce the speckle-like effect in the image. The temporal bandwidth of the random phase plate is narrow because of standing waves in it. To reduce standing waves the diffuser is intimately coupled to a wedged transducer. This combination is used to obtain diffuse insonification with broad spatial and temporal bandwidth.

Analysis of Spherical Target Illumination with Partially Coherent Light through Random Phase Plate

1998 ◽  
Vol 37 (Part 1, No. 10) ◽  
pp. 5560-5568 ◽  
Author(s):  
Kouji Tsubakimoto ◽  
Masahiro Nakatsuka ◽  
Noriaki Miyanaga ◽  
Takahisa Jitsuno
Keyword(s):  
Random Phase ◽  
Phase Plate ◽  
Coherent Light ◽  
Spherical Target ◽  
Partially Coherent ◽  
Partially Coherent Light

scholarly journals Pulsation of laser–plasma interaction explained by density ripple buildup and relaxation for understanding smoothing by random-phase plate, ISI, and broadband

1991 ◽  
Vol 9 (2) ◽  
pp. 381-395 ◽  
Author(s):  
Gu Min ◽  
H. Hora
Keyword(s):  
Laser Plasma ◽  
Laser Field ◽  
Bragg Reflection ◽  
Random Phase ◽  
Turnaround Time ◽  
Phase Plate ◽  
Direct Drive ◽  
Plasma Interaction ◽  
Laser Plasma Interaction ◽  
Plasma Corona

In recent years experimental results about the pulsation of reflectivity or 3ω/2 harmonics from laser-irradiated plasma with a period of 10–20 ps initiated a reconsideration of a broad field of phenomena of laser-plasma interaction. We present here numerical results from a very general hydrodynamic computation showing that the pulsation is due to a standing-wave-produced density ripple in the widespread plasma corona causing these after 2 ps at Laue-Bragg reflection at very low density, followed by a hydrodynamic relaxation of the ripple. This cycle has a turnaround time of about 6–10 ps and immediately explains the observation of pulsation. The suppression of pulsation and the achievement of smooth direct drive is then understood by a washing-out process of the ripples when using the random-phase plate (RPP) or broadband irradiation, or by just preventing the buildup of the ripple at the induced spatial incoherence (ISI), where coherence of the laser field is 1 or 2 ps only.

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