Four-Element Plastic Imaging Lens with Aspheric Surfaces

The patent uses a composite lens structure combining plastic aspherical lens elements with a glass lens element. Specifically, it employs plastic lens elements with higher Abbe numbers (lower chromatic aberration) combined with a glass element that provides the necessary refracting power. This composite approach allows the lens to achieve both compact size and reduced chromatic aberration by leveraging the advantages of different materials.

The patent changes the material parameters (Abbe number, refractive index) and geometric parameters (radius of curvature, lens shape) to optimize performance. By selecting plastic materials with specific Abbe numbers and designing aspherical surfaces with precise curvature radii, the lens achieves compact length while controlling chromatic aberration through parameter optimization rather than relying on traditional glass spherical lenses.

The patent replaces difficult-to-manufacture glass spherical lenses with plastic aspherical lens elements. Plastic lenses are easier and cheaper to fabricate, especially with aspherical surfaces that can be molded. This substitution maintains the compact size advantage while significantly improving manufacturability and reducing production costs.

The patent employs a hybrid lens design where plastic aspherical elements are combined with a glass element. The plastic components are designed to be easier to manufacture with standard molding techniques, while the glass element provides specific optical functions. This composite approach balances fabrication ease with optical performance requirements.

The patent creates a composite lens system combining plastic and glass materials. The plastic lens elements provide cost and weight advantages, while the glass element compensates for chromatic aberration. This strategic material combination allows the lens to achieve both economic benefits and optical performance that neither material could achieve alone.

The patent optimizes the optical parameters (refractive index, Abbe number) of the plastic lens elements and their arrangement to minimize chromatic aberration. By carefully selecting and configuring plastic materials with specific optical properties, the lens reduces chromatic aberration while maintaining the cost and weight advantages of plastic over pure glass constructions.