Five-Lens Optical Imaging System with Aspherical Surfaces

The optical imaging lens is divided into five separate lens elements with different focal powers and surface configurations. This segmentation allows each element to be optimized for specific functions: the first lens (positive focal power) gathers light, the second lens (negative focal power) corrects spherical aberration, the third lens (positive focal power) provides additional focusing, the fourth lens (positive focal power) corrects chromatic aberration, and the fifth lens (negative focal power) fine-tunes the optical path. By distributing the optical correction tasks across multiple elements, the system achieves large aperture while maintaining high imaging quality.

The patent employs aspherical surfaces on multiple lens elements (first, third, and fourth lenses have at least one aspherical surface). Aspherical surfaces are crucial for correcting spherical aberration that occurs in large aperture lenses. The aspherical profiles allow precise control of light ray paths, enabling the lens to maintain high resolution and low distortion across the entire aperture, thus resolving the contradiction between large aperture and imaging quality.

Each lens element in the five-element system is designed to perform multiple functions simultaneously. For example, the first lens with positive focal power not only gathers light but also begins the correction of spherical aberration through its aspherical surface. The second lens with negative focal power corrects spherical aberration while also contributing to chromatic aberration correction. This multi-functionality reduces the need for additional dedicated correction elements, optimizing the balance between imaging quality and system complexity.

The patent systematically varies key parameters across the five lens elements: focal power alternates between positive and negative values, surface types transition from spherical to aspherical and back, and the arrangement of surfaces (convex/concave) changes to optimize specific aberration corrections. These parameter changes allow each element to be tuned for specific correction tasks, achieving high imaging quality with a manageable number of components rather than requiring many identical or similar elements.