摘要：This study presents a new m.thod for designing algorithm.for a triplet lens with one or two elem.nts that are m.de of a gradient index m.dium.(GRIN). This m.thod is based upon considering a well-known designed triplet lens (Cooke triplet lens) as a target lens for designing of the Hybrid Triplet Lens (HTL). Our design was based upon keeping the total optical path length for the axial ray fixed for each case of design. The results showed that several designs for the HTL have the sam. total powers of the target lens. These designs depend on the variation of the GRIN elem.nt param.ter values and the order of the GRIN elem.nt position in the system. These HTL designs have been evaluated by considering several optical m.rit functions, i.e., the root m.an square (Rm.) spot radius, wave front error and the spherical aberration. To achieve the optim.l design, these functions are com.ared for the target lens and the HTL designs through a wide range of field angles.