Lens module for image capture

An optical module having an object side and an image side;

• the module comprising, from the object side to the image side:
• a first positive meniscus lens having a focal length F1 and comprising first and second optical surfaces, the first optical surface being convex and facing the object side, and the second optical surface being concave and facing the image side;
• a second positive meniscus lens having a focal length F2 and comprising third and fourth optical surfaces, the third optical surface being concave and facing the object side, and the fourth optical surface being convex and facing the image side;
• the four surfaces having their curvatures defined by the equation:
• Zi=CURViYi2/(1+(1−(1+Ki)CURVi2Yi2)½)+(Ai)Yi2+(Bi)Yi4+(Ci)Yi6+(Di)Yi8
• and the parameter
• Mi=1−(1+Ki)(CURVi)2(Ri)2
• 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 this surface with the optical axis;
• Ki is a constant called the conic constant of the i-th surface;
• CURVi is the curvature of the i-th surface at the intersection of this surface with the optical axis;
• Ai, Bi, Ci, Di, are, respectively, the aspheric coefficients of the 2nd, 4th, 6th, and 8th order of the i-th surface;
• Ri is the effective radius of aperture of the i-th surface;
• the module being characterized in that the following relations are satisfied:
• 0.60<F1/F2<1.45
• 2<sqrt(M2/M1)<7,
• wherein the Sagital and Tangential MTF values, measured at a spatial frequency of 143 line pairs per mm, differ by less than 20% for a FOV varying from zero to 26 degrees.

An optical module having an object side and an image side;

• the module comprising, from the object side to the image side:
• a first positive meniscus lens having a focal length F1 and comprising first and second optical surfaces, the first optical surface being convex and facing the object side, and the second optical surface being concave and facing the image side;
• a second positive meniscus lens having a focal length F2 and comprising third and fourth optical surfaces, the third optical surface being concave and facing the object side, and the fourth optical surface being convex and facing the image side;
• the four surfaces having their curvatures defined by the equation:
• Zi=CURViYi2/(1+(1−(1+Ki)CURVi2Yi2)½)+(Ai)Yi2+(Bi)Yi4+(Ci)Yi6+(Di)Yi8
• and the parameter
• Mi=1−(1+Ki)(CURVi)2(Ri)2
• 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 this surface with the optical axis;
• Ki is a constant called the conic constant of the i-th surface;
• CURVi is the curvature of the i-th surface at the intersection of this surface with the optical axis;
• Ai, Bi, Ci, Di, are, respectively, the aspheric coefficients of the 2nd, 4th, 6th, and 8th order of the i-th surface;
• Ri is the effective radius of aperture of the i-th surface;
• the module being characterized in that the following relations are satisfied:
• 0.60<F1/F2<1.45
• 2<sqrt(M2/M1)<7,
• wherein the Sagital and Tangential MTF values, measured at a spatial frequency of 71.5 line pairs per mm, differ by less than 6% at an FOV varying from zero to 26 degrees.