Apochromatic lens: Compound lens corrected for chromatic aberration, i.e. the three primary colours , red, green and blue are corrected. Also called Apochromat.

复合式透镜：即是红、绿和蓝三都。

By chiseling a BOL on a surface of a lens, a apochromatic system is composed, which actualizes the system's apochromatism, as well as revising primary aberration.

并将二元光学面刻画在透镜表面，在校系统初级像同时，实现了系统复消。