同轴双无衍射光的理论与实验

提出同轴双无衍射光的概念。如果两束汇聚角略有不同的同轴无衍射光同时存在,则它们相互之间叠加干涉后产生一种纵向呈周期变化的光场结构,这是一种新的光束空间分布,这种光束在横向仍是一种同心环光斑,可用于精密对准。而在不同纵向位置,这些同心环的强度分布是不同的,且是周期性变化的。同轴双无衍射光的轴向周期性可用于沿光束传播方向的定位。文中提出了双环缝法、分段圆锥透镜法、正弦相位环光栅法等实现同轴双无衍射光的理论与实验方法,分析了同轴双无衍射光的横向与纵向传播的衍射光斑特性,理论计算与实验测量的结果基本相符合。

Theory and Experiments of Coaxial Di-Nondiffracting Beam

The concept of coaxial di-nondiffracting beam is proposed. If two nondiffracting beams with small difference of convergence angle and common axis exist at same time, they will interference with each other to form a light field structure that varies periodically along the propagation direction. It is a new kind of space distribution of light beam. The cross-section of this beam is still rings fringe pattern with common center that can be used for precision alignment. However in different longitudinal position, the intensity distribution of these rings is different and varies periodically. The periodicity of the coaxial di-nondiffracting beam can be used for the positioning along the propagation direction. It is shown that the annular di-slit, axicon consisting of two conic surface and sine phase ring grating are capable of generating coaxial di-nondiffracting beam in theory and experiments. The diffraction pattern characteristics of coaxial di-nondiffracting beam along both transverse direction and longitudinal direction are analyzed. The experimental result fits to theoretical prediction basically.