Acquisition And Analysis Of Partial Skylight Polarization Distribution Pattern

During the transmission process in the atmosphere of the sunlight, polarized light is generated by the atmospheric scattering of air molecules and aerosol particles. Different beams of polarized light in the sky with various polarization states form the skylight polarization distribution pattern. A relatively stable skylight polarization distribution pattern exists in the sky at a fixed position during a specific time period, which follows certain distribution principles, containing abundant spatial location information. The research of biologists shows that many insects have special neuronal structure, which is quite sensitive to polarized light and able to extract polarization information from the partial skylight polarization distribution pattern to complete navigation. As the foundation to implement polarized light navigation, the perception and analysis of partial skylight polarization distribution pattern is of great importance.The tasks completed in this thesis are as follows:1) The basic theories related with skylight polarization distribution pattern are introduced first, including the polarization of light, atmospheric scattering phenomenon, the forming process and influencing factors of skylight and the mathematical description of the polarized characteristics.2) The design of the partial skylight polarization distribution pattern detection system is proposed. A summary of current detection devices and the measurement principle of detection system in this thesis are presented. Then three image-based detection systems designed in this thesis are introduced, including the single-channel device for validation with zoom lens, the single-channel device for validation with prime lens and three-channel real-time synchronous device. The hardware structure, software implementation process and the characteristics of the above three systems are respectively elaborated.3) The advantages and disadvantages of each system are summarized combined with the result of corresponding outdoor experiment, explaining the influence of focal length of the device on the experiment result. The focal length acts as a crucial factor to determine the field of view of the detection system. With comparison between the experiment result and the theoretical pattern, the detection system designed in this thesis proves to be stable and reliable to measure the partial skylight polarization distribution pattern. The outdoor experiment indicates that the partial skylight polarization distribution pattern is relatively stable, symmetrically distributed around the neutral point. The influence of cloud on the skylight polarization distribution pattern is preliminarily researched. The experiment shows that the degree of polarization is more easily affected by the cloud compared with the angle of polarization.