Five-Lens Imaging System with Aspheric Fifth Element

The patent applies parameter changes by optimizing the refractive powers and curvature radii of the five lens elements to satisfy specific conditional expressions. By carefully controlling parameters such as the ratio of focal lengths (0.3 < f1/|f2| < 1.5) and curvature radii relationships, the lens achieves high imaging performance with reduced total length. The fifth lens specifically uses aspheric surfaces with controlled curvature parameters to compact the overall structure while maintaining resolution quality.

The patent employs spheroidality by using aspheric surfaces on the fifth lens (and potentially other lenses). The aspheric shape allows for better control of light rays across different field angles, enabling high resolution performance with a more compact lens configuration. The specific curvature relationships defined in the conditional expressions optimize the spherical and aspheric surface geometries to reduce total lens length while maintaining imaging quality.

The patent maintains imaging performance in compact form by precisely controlling optical parameters. The conditional expressions define optimal ranges for refractive power ratios (e.g., 0.3 < f1/|f2| < 1.5, 0.5 < f45/f4 < 2.0) and curvature relationships that simultaneously achieve short total length and high resolution. These parameter optimizations ensure that even with reduced physical dimensions, the lens delivers quality imaging performance suitable for high-resolution sensors.

The use of aspheric surfaces on the fifth lens enables the patent to maintain high imaging performance in a compact configuration. The aspheric geometry provides superior aberration correction compared to simple spherical surfaces, allowing the lens to achieve diffraction-limited performance across the field of view despite the reduced total length. This is particularly important for maintaining peripheral image quality in compact lenses.