Endoscope Objective Lens Design for Error-Tolerant Wide-Angle Imaging

The patent applies parameter changes by carefully selecting and optimizing the focal lengths of individual lenses (f1, f2, f3, f4) and their ratios relative to the total focal length (f). Specifically, it sets f1/f within -0.5 to -0.1, f2/f within 0.3 to 0.7, and f3/f within 0.4 to 0.8, among other parameters. This systematic parameter optimization allows the small-sized lens to maintain stable optical performance despite manufacturing and assembling errors.

The patent segments the objective lens into multiple lens elements (at least four lenses: L1, L2, L3, L4) with distinct functions. The first lens (L1) has negative power for wide-angle coverage, while the second (L2), third (L3), and fourth (L4) lenses have positive power for focusing and aberration correction. This segmentation allows the system to achieve both compact size and high optical performance by distributing optical power across multiple specialized elements rather than concentrating it in fewer lenses.

The patent applies preliminary anti-action by designing an optical system that inherently compensates for and suppresses the effects of manufacturing and assembling errors before they can significantly degrade performance. The specific focal length ratios and lens configurations are predetermined to minimize the impact of errors, thereby reducing the need for strict tolerance management during manufacturing while maintaining high optical quality.

The patent employs composite optical design by combining lenses with different optical properties (negative and positive powers) in a specific configuration. This composite structure allows the system to achieve a wide angle of view (90° or more) while simultaneously correcting for curvature of field and other aberrations, thereby maintaining high image quality across the expanded observation field.