Analysis Of The Imaging Quality And Research Of The Correction For The Aberration By Pechan Prism

The roof prism is commonly used for reversing and inverting the image in the telescope system and it can fold the light path which makes the instrument tighter. In geometrical optics, the roof prism can be equivalent to a plane parallel plate only when the two roof surfaces are perpendicular to each other and the roof ridge is straight, or else it will cause the double image. Attempts were made to minimize this doubling by increasing the accuracy of the roof angle on these prisms, but it did not help. This thesis, which is based on studying the roof prisms’ doubling and intended to correct the doubling, research the polarization transmission of the Pechan prism and the intensity distribution in the image plane when a pencil of light is incident normally on the first surface and analyze the relationship between the polarization transmission, the intensity distribution and the structure of the prism by using the theory of polarization ray tracing and unified theory of coherence and polarization. At last, we get the best way and the best condition to correct the polarization aberration. The main works and conclusions are listed as follows:1)There are two different polarization transmissions by a Pechan prism for a collimated beam. In Pechan prism, one beam will split into two paths.By the method of polarization ray tracing, we obtain the polarization transmission matrices and they are mutually transport matrix. They will change the polarization state of a incident light differently. The difference is characterized by polarization aberration, that are the two diattenuations are zeros and the retardances are the same-but the eigenvectors are different.2)Calculating the energy focusability, resolution and deformation, we get the effect of polarization aberration on the image quality and the concrete features are that the energy focusability decrease to 1-N2, the resolution in y direction reduces one time and the deformation is up to 100%.3)Based on the polarization transmission matrix and unified theory of coherence and polarization, we get the relationship between the intensity distribution in the image plane and the structure of prism and prove that N in the polarization transmission matrix represented the prism’s structure parameter. And we reach the conclusion of that N can represent the polarization aberration and the best condition to correct the polarization is N=0.4)Using the unified theory of coherence and polarization, we get that the intensity distribution is associated with not only the structure parameters, but also the incident polarization state. Analysis of the relationship between intensity distribution and incident polarization parameters shows that (1)the distance of the split increase with the increasing of degree of polarization and the bigger difference of the two spot;(2)the intensity distribution will change with the azimuth and ellipticity.5) According to the relationship between the N getting from polarization ray tracing and the structure of the prism, we know that the best condition (N=0) to correct the doubling need the reflection phase shift δs-δp=π. We design and deposit the single layer and multiply layers phase film and get the consistent correction effect by experiment.