Combining Binary Optics with Achromats to Revise Secondary Spectrum
利用二元光学和消色差复合透镜组合校正二级光谱色差

The formula of secondary spectrum was deduced founding on the aberration theory.Based on the formula,both the traditional way of using CaF2,using PK- TK and the way of Binary optics to eliminate secondary spectrum were calculated and optimized by ZEMAX.Both methods could decrease the secondary spectrum while chromatism had compensated well.Based on the counteracted characteristics of secondary spectrum between traditional achromats and binary optics,it can badly decrease by combining them together in the long focal optical systems.