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在空间光通信中,通信光要通过大气随机信道进行传输,但光的传输受到大气湍流的严重影响。故光传输方式的优劣直接影响着空间光通信质量的好坏,所以,为减少大气湍流对通信光的影响,将通信光调制为圆偏振光进行传输。为了证明圆偏振光在空间光通信传输中具有降低通信噪声的优越性,开展了一组验证实验(以下简称偏振降噪实验)。给出了在激光偏振降噪实验中,识别光斑并对光斑参数进行分析的一套方案:首先利用减背景法对图像进行预处理,消除静态背景的影响,然后结合局部动态阈值分割,轮廓提取及筛选的方法,检测并识别信标光斑,最后对采用圆偏振光传输前后光斑的平均亮度、背景的平均亮度以及光斑图像对比度进行计算与比较。从而从图像处理技术的角度验证了,圆偏振光在空间光通信过程中可以有效地提高信噪比和通信质量。本方案满足了偏振降噪实验实时性的要求,且有效实用。
In space optical communications, communication light is transmitted through atmospheric random channels, but the transmission of light is severely affected by atmospheric turbulence. Therefore, the quality of optical transmission directly affects the quality of optical communication in space. Therefore, in order to reduce the influence of atmospheric turbulence on communication light, the communication light is modulated into circularly polarized light for transmission. In order to prove that circularly polarized light has the superiority of reducing the communication noise in the space optical communication transmission, a series of verification experiments (hereinafter referred to as polarization noise reduction experiment) are carried out. In the experiment of laser polarization de-noising, a set of scheme of spot recognition and spot parameter analysis is presented. Firstly, the image is preprocessed by subtractive background method to eliminate the influence of static background. Then the local dynamic threshold segmentation and contour extraction And screening methods to detect and identify the beacon spot. Finally, the average brightness of the spot before and after circularly polarized light transmission, the average brightness of the background and the contrast of the spot image were calculated and compared. From the perspective of image processing technology, it is verified that circularly polarized light can effectively improve signal-noise ratio and communication quality in space optical communication. The program to meet the real-time requirements of polarization noise reduction experiment, and effective.