二面角是几何量测量的重要对象。测角方法众多，但可用于在机、自动化测量的方法仍相对匮乏。提出了一种基于非接触激光回转射线的二面角在机测量方法。激光位移传感器的测量射线在空间内绕固定轴旋转，构成回转射线，是测头的核心部分。回转射线扫掠待测工件表面，通过测量两被测平面与测头的距离信息并结合相应的数据处理，即可完成二面角的测量。测量装置作为机床的选配件，由数控机床主轴搭载，可实现在机测量。提出了基于非接触回转射线的二面角测量方法的数学模型，分析了相应的误差来源并实验验证了该方法的有效性。该方法可以较好地完成0°~120°范围内的角度测量，测量结果与三坐标测量机给出的相对真值进行了对比，实验结果表明，最大误差为14″，相对误差不超过0.048%。

The measurement of dihedral angle is one of the most important measuring tasks in geometric measurement. Numerous and diverse angle measuring methods are proposed. However, few in-situ and automatic measuring methods are seriously and vigorously studied. To this end, a novel and simple angle measuring method is proposed, which is based on non-contact rotary ray-scanning mechanism. The rotary rays, emitted from a laser displacement sensor rotates around a fixed axis, constitutes the kernel part of the measuring probe. Which is driven to scan the surface of the workpiece. The distances from the target planes to the probe are obtained and subsequent data analysis is applied to calculate the dihedral angle. As an optional accessory, the measurement probe can be installed on the spindle of numerical control machine for in-situ measurements. The detailed mathematical model as well as the associated tolerance analysis are presented and validating experiments are offered. The method can do well in angle measuring within a nominal measuring range from 0° to 120°. The results are compared against the relative true value offered by three-coordinate measuring machine. It is shown that the maximal error of measuring result is 14″, and relative error of the proposed approach can be lower than 0.048% even in in-situ complex measuring environments.