Nineteen-Lens Broadband Objective for High-Resolution Large-Field Imaging

The objective lens is divided into 19 individual spherical lens elements arranged in sequence along the optical axis. These lenses are grouped into multiple cemented lens units (e.g., first and second lenses form a cemented lens, third, fourth and fifth lenses form another cemented lens). This segmentation allows each lens element to contribute to different aspects of optical performance, enabling simultaneous achievement of high numerical aperture (0.5-1.0) and large field of view (≥6mm) by distributing the optical correction functions across multiple elements.

The objective lens employs multiple lens elements made from different optical materials with varying refractive indices and dispersion characteristics. Specific lenses use materials such as BK7, SF5, F2, LAF1, and other optical glass types. This composite material approach enables the lens to achieve broadband performance across visible (400-700nm) and near-infrared (700-1000nm) wavelengths by compensating for chromatic aberrations through the combined optical properties of different materials, while maintaining feasible manufacturing precision requirements.

The objective lens incorporates multiple cemented lens units where adjacent lens elements are optically bonded together without air gaps. Specifically, the first and second lenses form a cemented lens, the third, fourth and fifth lenses form another cemented lens, and similar combinations continue through the 19-lens structure. This merging eliminates air-glass interfaces that would cause reflections and scattering, thereby improving imaging quality and reducing ghost images. The cemented structure is achieved through optical adhesive bonding, which, while requiring precise alignment during manufacturing, provides a reliable and repeatable process that balances manufacturing complexity with performance benefits.