Four-Lens Camera Assembly Optimizing Field-of-View and Weight

The patent applies parameter changes by optimizing the refractive indices, curvatures, and thicknesses of each lens element. Specifically, the first lens has a positive refractive power with specific curvature relationships (0.2<r1/|r2|<0.5), and subsequent lenses have controlled refractive powers and surface curvatures. These parameter optimizations allow achieving wide-angle characteristics (field-of-view ≥ 70 degrees) with only four lenses, avoiding the need for additional lens elements that would increase weight.

Each lens element in the four-lens assembly performs multiple functions. The first lens not only provides positive refractive power but also contributes to correcting spherical aberration. The second and third lenses with negative refractive powers simultaneously expand the field-of-view and correct chromatic aberration. The fourth lens with positive refractive power finalizes the focusing while maintaining compact dimensions. This multi-functionality allows the compact four-lens design to achieve wide-angle performance without requiring additional specialized lenses.

The patent systematically optimizes multiple parameters including refractive indices (1.5<n1<1.7, 1.6<n2<1.8), curvature ratios (0.2<r1/|r2|<0.5, 0.5<|r3|/r4<1.5), and thickness-to-focal-length ratios (0.1<ct1/|f1|<0.3). These controlled parameter ranges enable achieving wide-angle characteristics with minimal lens elements, simplifying the overall device structure while maintaining high imaging quality and reducing alignment complexity during assembly.

The lens assembly is segmented into four distinct lens elements with specific functional assignments. The first lens (positive power) handles initial light convergence, the second lens (negative power) expands the field and corrects aberrations, the third lens (negative power) further refines the optical path, and the fourth lens (positive power) provides final focusing. This functional segmentation allows each element to be optimized independently within controlled parameter ranges, simplifying the design and manufacturing process compared to a single complex lens or excessive number of elements.

The patent employs precise parameter control to correct optical aberrations. The first lens has a positive refractive power with controlled curvature ratio (0.2<r1/|r2|<0.5) to minimize spherical aberration. The second and third lenses have negative refractive powers with specific curvature relationships (0.5<|r3|/r4<1.5) to correct chromatic and coma aberrations. The fourth lens with positive refractive power and controlled thickness ratio (0.1<ct4/f4<0.3) provides final focusing while maintaining image quality. These parameter optimizations enable wide-angle performance (field-of-view ≥ 70 degrees) with high imaging quality without requiring additional corrective lenses.

The patent converts the potential harm of negative refractive powers (which can introduce aberrations) into a benefit by strategically placing negative-power lenses (second and third elements) in specific positions within the optical path. The negative powers are used to counteract the spherical and chromatic aberrations introduced by the positive-power first and fourth lenses. This approach transforms what could be harmful aberration sources into corrective elements, achieving high imaging quality across the wide field-of-view without adding more lens elements.