Lens Assembly Aberration Correction via Segmented Refractive Power

The lens assembly is divided into multiple lens elements (first lens, second lens, third lens, and optional fourth lens) with different refractive powers and surface curvatures. Each lens element contributes differently to light convergence and aberration correction, enabling the system to achieve large aperture with compact overall length through optimized segmentation of optical functions.

The patent employs specific parameter relationships including the conditional expressions for focal lengths (f1, f2, f3, f4), radii of curvature (R11, R12, R21, R22, etc.), and axial thicknesses (d1, d2, d3, d4) to optimize the optical path. By carefully controlling parameters such as the ratio of focal length to radius of curvature and the axial positions of lens elements, the design achieves low F-number while maintaining compact dimensions.

Different lens elements are designed with specific local optical characteristics: the first lens has positive refractive power with a convex object-side surface, the second lens has negative refractive power, the third lens has positive refractive power, and the fourth lens (when present) has negative refractive power. Each lens element's curvature radii, thickness, and material properties are locally optimized to correct specific aberrations and maintain high resolution despite the compact overall size.

The patent uses lens elements with different refractive indices and Abbe numbers to achieve chromatic aberration correction in a compact design. By combining materials with complementary optical properties, the system maintains high resolution and color accuracy while minimizing the total lens length through efficient use of optical path space.

The patent provides a flexible lens assembly design where the fourth lens is optional, allowing the system to be configured as a three-lens or four-lens assembly depending on specific application requirements. This dynamic configuration approach enables optimization of resolution and aberration correction while controlling complexity by including only the necessary number of lens elements for each particular use case.

The patent establishes specific parameter ranges and conditional expressions that govern the relationship between focal lengths, radius of curvature, and axial thickness of each lens element. By adhering to these parameter relationships, the design achieves effective aberration correction and high resolution with a minimal number of lens elements, thereby reducing overall system complexity while maintaining superior optical performance.