提出了一种基于直角棱镜的同时测量三维转角的新方法。测量光束垂直入射到直角棱镜的斜边面，其反射光束产生2倍于偏摆及俯仰角的偏向，以聚焦透镜及位置敏感探测器(PSD)组成接收测量单元实现偏摆及俯仰角的测量，避免了直线度误差带来的影响；透射光束再经直角棱镜反向折回，其在纵向产生包含滚转角信息的位移，由两个四象限探测器(QD)差分测量，避免了二维直线度误差的串扰，实现了误差分离，同时增强了抗干扰能力。通过理论建模及仿真，进行了误差分析，论证了方案的可行性，在设定参数下，测角分辨率可达0.2″。

A novel method for simultaneously measuring three-dimensional rotation angles is presented based on rectangular-prism. The collimated beam is normally incident upon the hypotenuse-surface of rectangular-prism. The changes of reflection direction are measured by using the measuring unit consisting of a focusing lens and a position sensitive detector, which is double that of yaw and pitch. The longitudinal displacement introduced by roll is measured by differential measurement based on two quadrant photoelectric detectors, when the transmitted beam returns through the rectangular-prism. This method realizes errors separation, avoiding crosstalk of straightness errors, and enhances the ability of anti-interference by adopting differential measurement. The systemic model is established and feasibility of the method is verified by theoretical analysis and simulation. The resolution of the angles can reach to 0.2″, when the system parameters apply to the values supposed.