Calibration Of The Point-source Skylight Polarization Pattern Measurement System

In recent years, bionic navigation has become the hot spot in navigation field. Among those, the method of applying skylight polarization draws much attention among public for the reason of its stability. There are two typical methods to explore skylight polarization, which are the imaging skylight polarization pattern measurement system and the point-source skylight polarization pattern measurement system. The former occupies relatively larger proportion as it takes less time to measure and enable to gather the message of the whole sky directly. But it cannot get some points’ information in the sky effectively. On the other side it is just the advantage of point-source skylight polarization pattern measurement system. And because the two methods can improve each other, the point-source skylight polarization pattern measurement system is also a way that is worth working on.In order to make up the vacancy of this field, here comes a kind of point-source skylight polarization pattern measurement system which contains its process and result of design and calibration being discussed in this paper. First, the explanation of Rayleigh scattering theory, the physics foundation and the producing mechanism of skylight scattering have been presented. And there are four methods can be adopted to describe the polarization characteristics:Stokes vectors method, electrical victors method, Jones vectors method and Poincare sphere method. Then a measuring system about how to measure skylight polarization pattern has been presented, which is based on Muller Matrix and Stokes Vector. We work out a kind of point-source skylight polarization pattern measurement system with Stokes Vector method to get the I, Q, U, and the using the formula to get the DOP and AOP.In order to work out the performance criterion of the system, we proceed accurate experiments to calibrate it. Through measuring the polarization characteristics of the sun meridian plane, zenith point and the plane that vertical to sun meridian plane, we verify the Rayleigh scattering theory and test the accuracy and reliability of the system.In order to work out the influencing factors of the results, we find the influence of the wave band and the weather. And then the best wave bands for navigation has been found too.