In this paper, we describe the equations for the calculation of the different focus positions for the meridional and marginal rays of a plano-convex thick lens. The equations are exact and were obtained from the trigonometric ray trace analysis of a single meridional ray parallel to the optical axis of the lens. We apply these equations to derive the expressions of the paraxial focal lengths for a plano-convex thick lens.

中文翻译：

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平凸厚透镜的子午线和边缘线不同焦点位置的计算

在本文中，我们描述了平凸厚透镜子午线和边缘线不同焦点位置的计算公式。这些方程式是精确的，并且是从平行于透镜光轴的单条子午线光线的三角光迹分析获得的。我们应用这些方程式得出平凸厚透镜近轴焦距的表达式。