Abstract The subsurface damage depth of optical material introduced by lapping determines the efficiency of lapping and polishing process. In order to explore the subsurface damage (SSD) of fixed-abrasive lapping process, angle polishing method was employed to evaluate the SSD depth and damage form of soft-brittle material lithium niobate (LN) crystal. The influences of the grit size, the applied load and the hardness of pad matrix on SSD were investigated experimentally. The results show that: with the grit size decreasing form W28 to W14, the damage depth decreases by 70%. With the applied load decreasing form 15 kPa to 7 kPa, the SSD decreases by 40%. The dense and deep subsurface micro-cracks are caused by the hard matrix pad during lapping processing, while the matrix with low hardness causes plastic scratches on the surface/subsurface of the workpiece without obvious micro-cracks around the scratches. This study affords effective method for SSD evaluation and control of soft brittle materials such as LN crystal.

中文翻译：

---

铌酸锂晶体次表面损伤深度的固定磨料研磨研究

摘要 研磨引入的光学材料的亚表面损伤深度决定了研磨和抛光过程的效率。为了探究固定磨料研磨工艺的次表面损伤（SSD），采用角度抛光法评估软脆材料铌酸锂（LN）晶体的SSD深度和损伤形式。实验研究了磨粒尺寸、施加的载荷和垫基硬度对SSD的影响。结果表明：随着粒度从W28减小到W14，损伤深度减小了70%。随着施加的负载从 15 kPa 降低到 7 kPa，SSD 降低了 40%。密而深的次表面微裂纹是由研磨加工过程中的硬基垫引起的，而硬度低的基体会在工件表面/亚表面产生塑料划痕，划痕周围没有明显的微裂纹。该研究为LN晶体等软脆材料的SSD评估和控制提供了有效的方法。