In the present paper we describe the family of all closed convex plane curves of class \(C^1\) which have circles as their isoptics. In the first part of the paper we give a certain characterization of all ellipses based on the notion of isoptic and we give a geometric characterization of curves whose orthoptics are circles. The second part of the paper contains considerations on curves which have circles as their isoptics and we show the form of support functions of all considered curves.

中文翻译：

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在以圆为等光点的曲线上

在本文中，我们描述了类\(C^1\)的所有闭凸平面曲线的族，这些曲线以圆为等光点。在论文的第一部分，我们基于等视的概念给出了所有椭圆的特定表征，并给出了正视为圆的曲线的几何表征。论文的第二部分包含对以圆为等光点的曲线的考虑，我们展示了所有考虑的曲线的支持函数的形式。