Optoelectronics
Vol.07 No.04(2017), Article ID:22715,7 pages
10.12677/OE.2017.74015

Research on the Effect of Laser’s Transmission Characteristic by Various Atmosphere Environment Based on Fractal Theory

Chen Li, Yi Quan

Photoelectric Specialty, Department of Control, Academy of Armored Force, Beijing

Received: Oct. 28th, 2017; accepted: Nov. 11th, 2017; published: Nov. 17th, 2017

ABSTRACT

We simulate stable atmospheric environment and the same concentration of water vapor environment and smoke environment in our lab, and then we get the laser spot of our helium-neon laser in these three different environments with CCD sensor. Dealing with these images to get grayscale image and extract spots’ contour line. Writing programs to calculate contour lines’ fractal dimension and the result shows that laser’s transmission characteristic is less affected by stable atmosphere environment so that the fractal dimension is the smallest. Comparing to the smog of the same class, the influence of vapor on laser’s transmission characteristic is larger; for the fractal dimension is bigger and the spot’s diameter is larger and the energy density is lower. It is feasible to analyze that how different environments affect laser’s transmission characteristic by means of studying on laser spot’s fractal dimension.

Keywords:Matlab, Grayscale Images, Contour Line, Fractal Dimension, Transmission Characteristic

1. 引言

2. 实验数据处理

2.1. 原始图像处理

2.2. 光斑轮廓线提取

Figure 1. Figure of laser spot in reposeful air

Figure 2. Figure of laser spot in vapour

Figure 3. Figure of laser spot in smoke

3. 轮廓线分形维数的计算

Figure 4. Contour line of laser spot in reposeful air

Figure 5. Contour line of laser spot in vapour

Figure 6. Contour line of laser spot insmoke

$D=-\underset{r\to 0}{\mathrm{lim}}\frac{\mathrm{log}{N}_{\left(i\right)}\left(r\right)}{\mathrm{log}{r}_{i}}$ (1)

Table 1. Result of box-statistics

Figure 7. Fractal dimension of laser spot in reposeful air

Figure 8. Fractal dimension of laser spot in vapour

Figure 9. Fractal dimension of laser spot in smoke

4. 结论

1) 在理想情况下，激光在传播一定距离后，其光斑依然能够保持完整，轮廓线保持平整，分形维数为1，表示激光光斑的能量分布均匀。但是在实际大气环境下，大气分子对激光有吸收和散射作用，加上大气湍流的扰动，使得激光传输特性发生线性改变，光斑破碎，轮廓线不规则，分形维数大于1；2) 平稳大气环境下，湍流对激光的传输特性影响较小，所测得的数据显示接收到的光斑能量大、直径小，分形维数也较小。对于相同浓度的烟雾和水蒸气来说，水蒸气对激光的传输特性影响较大，吸收的激光能量大，光斑分散，形态上破碎也较为严重；3) 对激光光斑的分形维数计算表明，不同的大气环境会导致不同规则程度的光斑形态，通过分析分形维数来研究复杂大气环境对激光传输特性的影响是可以实现的。

Research on the Effect of Laser’s Transmission Characteristic by Various Atmosphere Environment Based on Fractal Theory[J]. 光电子, 2017, 07(04): 103-109. http://dx.doi.org/10.12677/OE.2017.74015

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