Determination of a laser source temporal-spatial degree of coherence

1982 ◽  
Vol 13 (5) ◽  
pp. 289-292 ◽  
Author(s):  
P Bouchaud ◽  
N G Gaggioli
Keyword(s):  
Laser Source ◽  
Degree Of Coherence ◽  
Spatial Degree

SOLUTION FOR THE PHOTOACOUSTIC WAVE EQUATION WITH A SINGLE SPATIAL DEGREE OF FREEDOM, BEER'S LAW ABSORPTION OF RADIATION AND MECHANICAL BARRIERS

2013 ◽  
Vol 27 (18) ◽  
pp. 1350135 ◽  
Author(s):  
F. HERRERÍAS-AZCUÉ ◽  
A. GONZÁLEZ-VEGA ◽  
J. TORRES-ARENAS ◽  
G. GUTIÉRREZ-JUÁREZ
Keyword(s):  
Wave Equation ◽  
Reflection Coefficient ◽  
Degree Of Freedom ◽  
Beer's Law ◽  
Pressure Peak ◽  
Spatial Coordinates ◽  
Spatial Degree ◽  
Beer’S Law ◽  
Sample Width ◽  
Plane Sample

A photoacoustic model with one degree of freedom in the spatial coordinates for a plane sample is studied. The model proposed considers a sample with Beer's law absorption immersed in a fluid with different acoustical impedance. An analytical solution for this problem is given. It is shown that the generated PA wave is composed of a pressure peak followed by a reflected and inverted pulse with diminished magnitude. It is also remarked that the form described for the pulse has a periodicity related to the sample's width and attenuated by the reflection coefficient. It is noted that, due to this attenuation, information about the sample's width is more easily detected at the irradiation side. Border cases are taken for equal impedances and infinite sample width.

scholarly journals Direct Position Determination of Noncircular Sources with Multiple Nested Arrays: Reduced Dimension Subspace Data Fusion

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yang Qian ◽  
Dalin Zhao ◽  
Haowei Zeng
Keyword(s):  
Data Fusion ◽  
Linear Array ◽  
Degree Of Freedom ◽  
Search Problem ◽  
Positioning Accuracy ◽  
Position Determination ◽  
Spatial Degree ◽  
Reduced Dimension ◽  
Nested Arrays

Direct position determination (DPD) of noncircular (NC) sources with multiple nested arrays (NA) is investigated in this paper. Noncircular sources are used to expand the dimension of the received signal matrix, so the number of identifiable information sources and the accuracy of direct position determination are improved. Furthermore, nested array increases spatial degree of freedom. In this paper, the high-dimensional search problem of noncircular sources is investigated. Therefore, we propose algorithm dimension reduction subspace data fusion (RD-SDF) to reduce complexity and increase positioning accuracy. Simulation results show that the proposed RD-SDF algorithm for multiple nested arrays with noncircular sources has improved positioning accuracy with higher spatial degree of freedom than SDF, Capon, and two-step algorithms with uniform linear array and circular sources (CS).

Perfect distribution of four-photon entangled states over an arbitrary collective noise channel by spatial degree of freedom

2013 ◽  
Vol 308 ◽  
pp. 304-308 ◽  
Author(s):  
Li Dong ◽  
Xiao-Ming Xiu ◽  
Hong-Zhi Shen ◽  
Ya-Jun Gao ◽  
X.X. Yi
Keyword(s):  
Degree Of Freedom ◽  
Entangled States ◽  
Collective Noise ◽  
Spatial Degree

On the Assessment of Nonlocal Climate Feedback. Part I: The Generalized Equilibrium Feedback Assessment*

2008 ◽  
Vol 21 (1) ◽  
pp. 134-148 ◽  
Author(s):  
Zhengyu Liu ◽  
Na Wen ◽  
Yun Liu
Keyword(s):  
Spatial Resolution ◽  
Sampling Error ◽  
Climate Feedback ◽  
Small Scale ◽  
Climate Feedbacks ◽  
Sst Variability ◽  
Multivariate Generalization ◽  
Potential Difficulty ◽  
Generalized Equilibrium ◽  
Spatial Degree

Abstract A statistical method is developed to assess the full climate feedback of nonlocal climate feedbacks. The method is a multivariate generalization of the univariate equilibrium feedback assessment (EFA) method of Frankignoul et al. As a pilot study here, the generalized EFA (GEFA) is applied to the assessment of the feedback response of sea surface temperature (SST) on surface heat flux in a simple ocean–atmosphere model that includes atmospheric advection. It is shown that GEFA can capture major features of nonlocal climate feedback and sheds light on the dynamics of the atmospheric response, as long as the spatial resolution (or spatial degree of freedom) is not very high. Given a sample size, sampling error tends to increase significantly with the spatial resolution of the data. As a result, useful estimates of the feedback can only be obtained at sufficiently low resolution. The sampling error is also found to increase significantly with the spatial scale of the atmospheric forcing and, in turn, the SST variability. This implies the potential difficulty in distinguishing the nonlocal feedbacks arising from small-scale SST variability. These deficiencies call for further improvements on the assessment methods for nonlocal climate feedbacks.

scholarly journals Experimental demonstration of multiple dimensional coding decoding for image transfer with controllable vortex arrays

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Long Zhu ◽  
Andong Wang ◽  
Mingliang Deng ◽  
Bing Lu ◽  
Xiaojin Guo
Keyword(s):  
Dimensional Space ◽  
Image Transfer ◽  
Light Modulator ◽  
Mode Amplitude ◽  
Data Coding ◽  
Coding Schemes ◽  
Amplitude Data ◽  
Spatial Degree ◽  
Flexible Generation ◽  
Vortex Array

AbstractVortex beams carrying orbital angular momentum (OAM), which featuring helical phase front, have been regarded as an alternative spatial degree of freedom for optical mode coding and multiplexing. For most reported OAM-based mode coding schemes, data information is only encoded by different OAM mode states. In this paper, we introduce a novel design technique to construct vortex array phase grating (VAPGs) for the flexible generation of vortex arrays, and employ the proposed VAPGs to realize multi-dimensional space/mode/amplitude coding/decoding. By designing VAPGs with different parameters and loading them on to a single spatial light modulator (SLM), we successfully generate vortex array with different mode states and relative power in the experiments. Moreover, a 10-bit multi-dimensional space/mode/amplitude data coding/decoding scheme for image transfer in free-space link with a zero bit-error-rate is experimentally demonstrated, which confirm the feasibility of our proposed VAPG-based coding/decoding scheme.

scholarly journals Experimental Demonstration of Multi-dimensional Coding/decoding for Image Transfer with Controllable Vortex Arrays

2021 ◽  
Author(s):  
Long Zhu ◽  
Andong Wang ◽  
Mingliang Deng ◽  
Bing Lu ◽  
Xiaojin Guo
Keyword(s):  
Dimensional Space ◽  
Image Transfer ◽  
Light Modulator ◽  
Mode Amplitude ◽  
Data Coding ◽  
Coding Schemes ◽  
Amplitude Data ◽  
Spatial Degree ◽  
Flexible Generation ◽  
Vortex Array

Abstract Vortex beams carrying orbital angular momentum (OAM), which featuring helical phase front, have been regarded as an alternative spatial degree of freedom for optical mode coding and multiplexing. For most reported OAM-based mode coding schemes, data information is only encoded by different OAM mode states. In this paper, we introduce a novel design technique to construct vortex array phase grating (VAPGs) for the flexible generation of vortex arrays, and employ the proposed VAPGs to realize multi-dimensional space/mode/amplitude coding/decoding. By designing VAPGs with different parameters and loading them on to a single spatial light modulator (SLM), we successfully generate vortex array with different mode states and relative power in the experiments. Moreover, a 10-bit multi-dimensional space/mode/amplitude data coding/decoding scheme for image transfer in free-space link with a zero bit-error-rate is experimentally demonstrated, which confirm the feasibility of our proposed VAPG-based coding/decoding scheme.

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