使用矩阵光学的方法得到了Offner展宽器等效光栅对表达式、经过Offner展宽器后脉冲的脉宽表达式及展宽器各元件尺寸的解析表达式。确定了一般化的设计步骤，并给出了一个设计实例。矩阵光学获得的解析结果与光线追迹方法获得的数值结果一致。

Effective grating pair distance of Offner triplet stretcher is obtained by matric optics. Pulse duration after stretcher calculated formula and the elements’size analytic expressions are obtained. A generalized solution designing a practical Offner stretcher and an example are provided. The analytic results are in agreement with the ray tracing results.