针对使用点光源的激光干涉仪在测量中容易出现相干噪声的问题,阐述了环形光源抑制相干噪声的原理,分析了环形光源半径及厚度与条纹可见度之间的关系,提出一种基于环形透镜产生环形光源的光学系统。该系统包括扩束系统、环形透镜和双远心镜头,根据菲索干涉仪中的准直镜头和干涉腔长得到环形光源的目标参数。使用Zemax分别设计了环形光源系统中的三个子系统,并保证各部分光学系统之间良好衔接。其中：环形透镜由一个非球面透镜旋转而成;双远心镜头可以使环形光源直径缩小到合理范围,并确保最后环形光源上每个离轴点的出射光束都与光轴平行。最终设计出环半径为0.38 mm、厚度为12.5 μm的环形光源,在准直透镜焦距为900 mm、干涉腔长为100 mm的情况下,干涉条纹可见度的理论值大于0.98。

To address the problem of coherent noise in laser interferometer measurements using a point source, the principle of coherent noise prevention using a ring source was described. Moreover, the relationship between the radius and thickness of the ring source and the visibility of fringes was analyzed. Further, to produce the ring source, an annular-lens-based optical system comprising a beam expanding system, annular lens, and double telecentric lens was proposed. The target parameters of the ring source were obtained according to the collimating lens and cavity length of the Fizeau interferometer. Additionally, ZEMAX was used to design three systems in the ring source system and ensure good connection between the optical systems. The annular lens was created by rotating an aspheric lens, and the double telecentric lens could reduce the ring source diameter to a reasonable range while ensuring that the outgoing beam from each off-axis point source in the final ring source was parallel to the optical axis. Finally, a ring source with an average ring radius of 0.38 mm and a thickness of 12.5 μm was designed. When the focal length of the collimating lens is 900 mm and the cavity length of the interferometer is 100 mm, theoretically, the visibility of interference fringes of greater than 0.98 can be achieved.