船载太阳光度计图像跟踪系统

Shipboard sun-photometer image tracking system

传统太阳光度计在海上移动平台上不能精准跟踪太阳。为了解决船舶在移动过程当中实现对太阳高精度跟踪的问题,利用鱼眼镜头、陀螺稳定平台、小视场CCD图像传感器等构建了船载型太阳光度计的图像跟踪系统。文中详细地描述了图像跟踪系统的整体结构和单臂探头的光路设计,介绍了时钟法与鱼眼成像系统相结合的方式在全天空大视场范围下进行太阳的粗跟踪,然后通过小视场的CCD图像处理技术来提高跟踪精度。此外,给出了系统的软件跟踪算法和流程,分析了系统跟踪的可靠性。该系统实现了在海上移动平台下的全自动跟踪测量,综合跟踪精度优于1′。与日本POM-01MKⅢ船用太阳光度计进行透过率与水汽的数据对比表明:在940 nm波段的大气透过率最大相对误差不超过7.6%,水汽含量最大相对误差不超过6.1%。该系统可以应用于船载太阳光度计测量海上整层大气透过率以及水汽数据,也可应用于其他对移动非稳定平台下太阳的跟踪。

Traditional sun-photometer cannot accurately track the sun on offshore mobile platform. In order to solve the problem of high-precision tracking of the sun in the process of ship moving, an image tracking system for shipboard sun-photometer(SSP) was constructed by using fisheye lens, gyro-stabilized platform and smallfield CCD image sensor. The whole structure of the image tracking system of the shipboard sun-photometer and the design of the optical path of the single-arm probe were introduced. The coarse tracking of the sun in the large field of view by the clock method and fisheye imaging system was described in detail, and then the fine tracking measurement was carried out by the CCD image processing technology of small field of view. Besides, the software tracking algorithm, process and system tracking reliability were given. The image tracking system of shipboard sun-photometer can be automatically tracked and measured on offshore mobile platforms, and the comprehensive tracking accuracy was higher than 1′. The data were compared with the Japanese POM-01 MKⅢsun-photometer. The results show that the maximum relative error of atmospheric transmittance at 940 nm band is less than 7.6%, and the maximum relative error of water vapor is less than 6.1%. The system can be applied to the shipboard sun-photometer to measure the atmospheric transmittance and water vapor at sea, and can also be used to track the sun on other moving unstable platforms.