为了高精度地检测长焦透镜的透射波前, 提出了在Zygo干涉仪的平面光路中加入一个二元衍射元件提供参考波前的计算全息法(CGH)。介绍了计算全息法检测长焦透镜透射波前的理论, 设计并研制了高精度计算全息板, 并将其用于大口径长焦距透镜透射波前检测。理论分析和实际检测结果表明: 该方法系统误差小, 测量重复性精度优于0.004 λ(2σ RMS), 与常规的菲索干涉法测量球面透镜透射波前得到的结果一致, 从而验证了提出测量方法的可靠性。最后, 详细分析了二元衍射元件的制造误差对透射波前检测的影响, 得到测量误差(PV)小于λ/10。文中的结果表明提出的计算全息法可有效缩短光路, 提高测量精度, 对长焦透镜波前检测有重要的应用价值。

To measure the transmissive wavefront of a long-focal length lens precisely, a novel Computer Generated Holography (CGH) was proposed by adding a binary diffractive optical element into the Zygo interferometer to provide a reference wavefront. The theory of transmissive wavefront measurement of large convex lens by using the CGH was introduced. A high precision computed holographic plane was designed and developed to apply in the measurement of the transmissive wavefront of the long-focal length lens. The theory analysis and practical test show that the proposed method has a lower systematic error, and the measuring repeatability of the CGH is better than 0.004λ (2σ RMS).The result is in agreement with that of common Fizeau interferometry, and verifies the feasibility of the proposed CGH. Finally, the measurement uncertainty due to the substrate error and hologram fabrication processes was analyzed, and the wavefront peak-valley error is less than λ/10. It concludes that the CGH method greatly shortens the airspace, improves measurement precision, and is of great importance for the wavefront measurement of long focal length lenses.