Two lens module including a plano-convex lens

Abstract

An optical module () comprises a positive meniscus lens () having a focal length Fand comprising a first convex optical surface () and a second concave optical surface (), and a plano-convex lens () having a focal length Fand comprising a third flat optical surface () and a fourth convex optical surface () from an object side () to an image side (). The curvatures of the four optical surfaces () are defined by the equation: Zi=CURViYi2/(1+(1+Ki)CURVi2Yi2)½)+(Ai)Yi2+(Bi)Yi4+(Ci)Yi6+(Di)Yi8, and the two lenses are defined by 0.35<F/F<0.90, 0.30<Conv2/Conv<0.70, and 0.50<M1/M2<1.20; where: i is the surface number (i=1 to 4); for the i-th surface, Zi is the distance between a point on the aspheric surface at the height of Yi above the optical axis and a plane tangent to the aspheric surface at the intersection of the surface with the optical axis; Ki is the conic constant; CURVi is the curvature at the intersection of the surface with the optical axis with CURV3=0; Ai, Bi, Ci, Di are the aspheric coefficients of the 2nd, 4nd, 6nd and 8nd order with A3=0, B3=0, C3=0, D3=0; Ri is the effective radius of aperture; Mi=(1−(1+Ki)(CURVi)2(Ri)2)½; and Conv2 and Conv are the convergence of the second lens () and the complete lens module (), respectively.