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A phase screen simulation method for light propagating in short distance in underwater turbulent flow

A phase screen, close-range technology, applied in design optimization/simulation, instrumentation, calculation, etc., can solve the problem that the phase screen model cannot truly simulate the turbulence characteristics, and the multi-layer phase screen does not consider the phase screen correlation.

Inactive Publication Date: 2019-08-23
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to solve the shortcoming that the correlation between the phase screens is not taken into account in the multi-layer phase screen of the prior art, so that the phase screen model cannot truly simulate the characteristics of the turbulent flow, and proposes a method for light near underwater turbulent flow. Phase Screen Simulation Method for Distance Propagation

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  • A phase screen simulation method for light propagating in short distance in underwater turbulent flow
  • A phase screen simulation method for light propagating in short distance in underwater turbulent flow
  • A phase screen simulation method for light propagating in short distance in underwater turbulent flow

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specific Embodiment approach 1

[0028] Specific Embodiment 1: The phase screen simulation method of light propagating in close distance in underwater turbulent flow in this embodiment, as shown in figure 1 shown, including the following steps:

[0029] Step 1) Input the initial image, and the initial image is used to generate phase screens with mutual correlation; the pixel value of the pixel in the initial image is used to represent the phase value; the pixel value and the relative difference of each pixel in the initial image are obtained by Labeled as known values; a specific number and position of pixel points in the original image and phase screen are chosen as fiducials, and each row and column has the same number of fiducials.

[0030] The initial image is Figure 3(a), each square is a pixel point, and the initial image also belongs to the phase screen, and each three points in the figure are marked as reference points, and there are 9× in Figure 3(a) 9 = 81 fiducials. The pixel values ​​and relativ...

specific Embodiment approach 2

[0056] Embodiment 2: The difference between this embodiment and Embodiment 1 is that the three-dimensional covariance matrix prediction model is used to calculate the phase fluctuation between any two points in space, and its calculation formula is:

[0057]

[0058] The phase covariance function describes the phase fluctuation of any two points in space, and it represents the relative fluctuation, which has nothing to do with the real phase value.

[0059] r1, r2 represent any two spatial position vectors; D φ is the phase structure function; T is the weight function, whose value is 1 in the discrete area and 0 outside the area; C is the phase covariance function.

[0060] Other steps and parameters are the same as those in Embodiment 1.

specific Embodiment approach 3

[0061] Specific embodiment three: the difference between this embodiment and specific embodiment one or two is:

[0062] In step 2), the calculation formula for the pixel value of the jth reference point in the i-th phase screen to be generated is:

[0063]

[0064] x i ,y j ,z k are the components of any point in the space in the x direction, y direction and z direction; where A is the prediction matrix, φ m is the known phase column matrix, σ is the interpolation standard deviation, and R is a Gaussian random variable with a variance of 1 and a mean of 0. The form of the prediction matrix A is:

[0065]

[0066] The interpolated standard deviation is of the form:

[0067]

[0068] The specific derivation process is:

[0069] For a random screen group of k-layer i×j size, the random screen can be expressed as k matrixes of i×j size, for example, the k-th layer random screen can be expressed as:

[0070]

[0071] Perform column vectorization processing on th...

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Abstract

The invention relates to a phase screen simulation method of short distance transmission of light in underwater turbulent flow, and belongs to the field of underwater target detection. The phase screen simulation method of short distance transmission of light in underwater turbulent flow is provided for solving the shortcomings that a phase screen model cannot really simulate the properties of turbulent flow as the correlation between phase screens in multiple layers of phase screens is not considered in the prior art. The method comprises the following steps: inputting an initial image; calculating a pixel value of a current reference point by using a reference point with a known value; calculating a relative pixel difference; calculating an absolute value of the reference point; repeating the above process until left and right reference points of all phase screens are calculated; generating multiple processes, wherein each process contains one framework; simultaneously calculating the absolute value of each point in the framework by using a parallel calculation method; repeating the process of calculating the absolute value of each point of each process; and repeating the above steps until all points are calculated. The phase screen simulation method provided by the invention is suitable for the analogue simulation of a transmission model of light in underwater turbulent flow.

Description

technical field [0001] The invention relates to a phase screen simulation method for short-distance propagation of light in underwater turbulent flow, belonging to the field of underwater target detection. Background technique [0002] The detection of underwater targets is one of the important branches of ocean detection. For a moving underwater target, turbulence is bound to be generated during its movement. Converting the direct detection of the target into the indirect detection of the turbulent field generated by it is an important detection method. Therefore, the research on the characteristics of the underwater turbulence field is the main problem in the research of underwater detection. When using laser to study the characteristics of underwater turbulence, for light propagation, the main influence of turbulence is the random fluctuation of the phase of light waves caused by the fluctuation of the refractive index of the water medium. Therefore, establishing the p...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F17/50
CPCG06F30/20
Inventor 王翰韬张宇张华俊
Owner HARBIN INST OF TECH
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