Fig. 1. Optical-path-length change caused by figure errors.

Fig. 2. Establish initial planar system.

Fig. 3. (a) Forward ray tracing; (b) reverse ray tracing.

Fig. 4. Shifting image points to change AOIs on the TM.

Fig. 5. (a) Initial planar system; (b) initial freeform surfaces system; (c) freeform surfaces system with |θ1| greater than w1; (d) freeform surfaces system, in which |θ1|, |θ2| are greater than w1, w2, respectively; (e) initial system with low surface-figure-error sensitivity, in which |θ1|, |θ2|, and |θ3| are greater than w1, w2, and w3, respectively; (f) optimized system; (g) field map of the RMSWFE.

Fig. 6. (a) Initial planar system; (b) initial system designed by CI-3D method; (c) optimized system; (d) field map of the RMSWFE.

Fig. 7. Sensitivity curve of the two systems to surface figure errors. (a) PM; (b) SM; (c) TM.

Table 1. Optical System Specifications

Table 2. Absolute AOIs on Each Surface of the Systems in Fig. 5a