设计了一种基于干涉检验法的复制拼接光栅测量光路。针对光栅复制拼接光路中入射光角度难以精确测量的问题，分析了光栅拼接实验中入射光角度对光栅拼接的影响。建立了光栅拼接误差模型，分析了五维拼接误差的容限要求。按照光栅复制拼接光路的要求，设计了一种干涉仪角度调节装置。根据误差模型和拼接光路分析了500 mm×500 mm大尺寸中阶梯光栅复制拼接光路中入射光角度误差与拼接误差的关系。 结果显示：入射光角度误差为1°，拼接光路中绕x轴，y轴的转动误差Δθx,Δθy和沿z轴的位移误差Δz的计算值与实际值之间分别相差0.002 1 μrad，0.003 3 μrad和0.348 2 nm时，引起波前差为2.590 1 nm。根据这一计算结果，给出了干涉仪角度调节装置的设计指标，即设置角度调节分度为0.1°时，可满足大尺寸光栅复制拼接要求。

A measuring path for grating replication and mosaic was designed based on interferometric method. In consideration of the difficulty of measuring incident light angles in the optical path for grating replication and mosaic, the influence of the angle error of the incident light on the grating replication and mosaic was analyzed. A mathematical model of mosaic grating errors was established, and the tolerance of the mosaic grating errors was given. According the requirement of incident light angle in the optical path for grating replication and mosaic, an angle adjustment structure of the interferometer was designed. On the basis of error mathematical model and the mosaic path, the relation between the incident angle error and the mosaic grating errors was analyzed for a 5 000 mm×500 mm large echelle grating. The results show that when the incident angle error is 1°, and the differences of calculation value and actual value for the Δθx, Δθy, Δz( mosaic grating errors around the x,y,z axes) are 0.002 1 μrad，0.003 3 μrad，0.348 2 nm, respectively, the wavefront error is 2.590 1 nm. Accroding to the calculation and analysis, it shows that the angle adjustment structure of the interferometer needs a dividing plate of 0.1° as the min measuring range , which can meet the requirement of the grating mosaic.