为解决在光学玻璃应力双折射测量中遇到的双折射叠加问题，利用光学等效原理，使用一个线性双折射模型和一个旋转器来代替叠加模型。对叠加的情况做了分析和计算，得到了叠加后的特征延迟、主应力方向和旋转角随两个应力模型主应力方向夹角变化的曲线。理论分析表明，应力双折射叠加不是应力双折射的简单相加，而是与叠加模型各自的应力双折射值和主应力方向的夹角有关。实验结果与理论计算相吻合。应力双折射叠加对实际光学玻璃测试造成不良影响，使测量精度降低，特别是有透光支撑机构或折射液容器的情况下，应力双折射叠加的影响不可忽略。

To solve the superposition problem of stress birefringence in measuring stress birefringence of optical glass, using optical equivalence principle, the superposition model was replaced by a system containing a birefringent plate and a rotator. The superposition of stress birefringence analyzed and calculated. Curves of phase retardation, azimuth of the principal axis of birefringent model, and rotation angle of the rotator changing with the angle between two azimuths of principal axis of the birefringent model were obtained. Results indicate that the superposition of stress birefringence is not a simple sum of it, it is related to the magnitude of birefringence and the angle of stress of each superposition model. The stress birefringence measurement value matches the theoretical value. The superposition of stress birefringence influences optical glass measurement adversely, reducing the measurement precision, especially when transparent support or refractive liquid containers exist, the influence of superposition of stress birefringence cannot be ignored.