Ｄesign of correction of secondary spectrum by hybrid diffractiverefractive

Binary optics can be used for increasing optical performances，decreasing size and weight，and decreasing systems costs in numerous applications．Many types of optics can be fabricated using diffractive surfaces that standard refractive lenses are not possible．By means of hybrid diffractive-refractive，using two kind glasses，a method and processes of apochromats have been introduced to realize for decreasing secondary spectrum in long focus Telescope for secondary planet in detail．The research results showed：secondary spectrum do not affect the quality of sight field the in corrected Telescope．The correction method is simple and satisfiable.