A major modification has been made to the conventional mode-locked femtosecond laser autocollimator so that the apex angle of a small prism, which is a transparent object difficult to be measured by the conventional optical methods, can be measured. In the oblique-incidence optical setup, a collimated mode-locked femtosecond laser is at first made incident to a target prism, and the laser beam reflected from the prism surface is then projected onto a reflective-type grating for angle measurement based on the principle of the femtosecond laser autocollimator. With the robust signal processing technique in the femtosecond laser autocollimator where the spectrum of the first-order diffracted beams emanated from the grating is captured by the fiber detector, high-precision angle measurement can be realized even on a surface having a small area for measurement and/or on a surface having low reflectivity. An oblique-incidence femtosecond laser autocollimator with a fiber-based femtosecond laser source is developed, and its basic characteristics are then evaluated in experiments. An experimental setup composed of the oblique-incidence femtosecond laser autocollimator and a high-precision rotary table is also constructed for prism angle measurement. To avoid the influence of the internally reflected beam in a prism, a method employing the characteristic of Brewster's angle is newly proposed, and its feasibility is verified through experiments. The uncertainty analysis on the measurement of the prism apex angle by the oblique-incidence mode-locked femtosecond laser is also carried out based on GUM.

对常规锁模飞秒激光自准直仪进行了重大修改，以便可以测量小棱镜的顶角，该小棱镜是难以通过常规光学方法测量的透明物体。在倾斜入射光学装置中，首先使准直锁模飞秒激光入射到目标棱镜，然后将根据棱镜原理从棱镜表面反射的激光束投射到反射型光栅上进行角度测量。飞秒激光自动准直仪 借助飞秒激光自动准直仪中强大的信号处理技术，光纤检测器捕获了从光栅发出的一阶衍射光束的光谱，即使在用于测量的面积小的表面上和/或在具有低反射率的表面上也可以实现高精度的角度测量。研制了具有光纤飞秒激光源的斜入射飞秒激光自准直仪，并在实验中对其基本特性进行了评估。还构造了由斜入射飞秒激光自动准直仪和高精度转台组成的实验装置，用于棱镜角测量。为了避免棱镜内部反射光束的影响，提出了一种利用布鲁斯特角特征的方法，并通过实验验证了其可行性。还基于GUM对斜入射锁模飞秒激光测量棱镜顶角进行了不确定度分析。