Prism

The utility model relates to a prism which comprises a support, a prism body and a guide rod. The prism body is mounted on the bracket and at least comprises a first mounting state; the guide rod is mounted on the prism body and extends to the back surface of the prism body; in the first installation state, the tail end of the guide rod is used for calibrating the measurement reference position of the prism. The device has the advantages of simple structure, capability of meeting different measurement scene requirements and the like. 本实用新型涉及一种棱镜，包括支架、棱镜体和导向杆；所述棱镜体安装在所述支架上，且至少包括有第一安装状态；所述导向杆安装在所述棱镜体上，并且延伸至所述棱镜体的背面；在所述第一安装状态下，所述导向杆的末端用于标定棱镜的测量基准位置。具有结构简单，满足不同测量场景需求等优点。