Astigmatism analysis by matrix methods in White Cells

摘要

White Cell is a typical multiple-path absorption cell for absorption spectroscopy. For multi-path enhanced absorption application, we should make sure that the input light of the multiple-path cell can be output as much as possible to enhance absorption signal. Thus the astigmatism of the White cell should be analyzed for optimization as a key factor. In White cell, the astigmatism is difficult to be calculated as the meridian and sagittal planes of the beam would rotate with a different angle while at each reflection. In this article, the White cell is presented by defined 4 × 4 optical matrices as a nonsymmetrical system. The astigmatic difference would then be obtained from the eigenvalues of the partitioned matrices. The numerical computation and ray-tracing simulation results presented have proved the efficiency of this method. The astigmatism can be improved by properly choosing the distance h between the two rows of image spots on the field mirror.