中文摘要：

利用单缝夫琅和费衍射装置，通过转动来使组成狭缝的一个棱边与另一固定棱边形成分离间隙，进而使观察屏上的衍射条纹出现不对称分布现象。用最小二乘法对由线阵CCD测量到的衍射图像的光强分布进行二次曲线拟合，并由拟合得到的数学表达式，确定衍射条纹的精确位置。推导出转动棱边在转动平面内两个相互垂直方向上的位移与观察屏上衍射暗纹位置之间的关系式，并利用它对转动棱边的转角进行计算。实验结果表明，新的测量方法可以实现小转角的高精度测量，转角的测量不确定度可达4．2″。

英文摘要：

Making use of the Fraunhofer diffraction device, the dissymmetry distributing phenomena of diffraction stripes can be seen on the observation screen, when the separating gap appears between two straight edges used to constitute a single slit by means of turning one edge and fixing the other. In order to ascertain the accurate positions of diffraction fringes according to math expressions, the least square method is used to fit quadratic curves of the intensity distribution detected by CCD. The relationship between the displacement of the turning edge in two perpendicular directions of turning plane and the positions of diffraction dark fringes can be determined and it can be used to calculate the small rotating angle. Experiments show the new method can be applied to measure small rotating angle accurately. The uncertainty of the rotating angle is 4.2＂.