Observation Optical System for Compact HMDs

The optical system is divided into multiple lens groups (first lens group with positive refractive power, second lens group with negative refractive power, third lens group with positive refractive power) that work together to share the refractive power burden. This segmentation allows the system to achieve the required optical performance without relying on a single strong reflective surface, thereby reducing thickness.

The patent optimizes the distribution of refractive power among different lens groups by controlling specific parameter ranges (e.g., focal length ratios, curvature radii). By carefully adjusting these parameters, the system achieves wide field of view and high optical performance while maintaining a compact thickness through balanced power distribution rather than concentrated power.

Instead of concentrating refractive power on one semi-transmissive surface, the patent segments the optical system into multiple lens groups with distributed refractive powers. The first lens group provides positive power, the second provides negative power, and the third provides positive power, creating a balanced distribution that reduces the curvature requirements of individual surfaces and thereby reduces thickness while maintaining structural simplicity.

The patent introduces a multi-group lens configuration that adds structural dimensionality to the system. By arranging lens groups in sequence along the optical path with specific interval relationships, the system achieves power distribution in multiple spatial dimensions, allowing thickness reduction while maintaining functional simplicity.

The total refractive power requirement is segmented across three lens groups rather than concentrated in one surface. The first lens group with positive power handles initial convergence, the second lens group with negative power provides divergence and aberration correction, and the third lens group with positive power completes the focusing. This segmentation allows each surface to have moderate curvature while collectively achieving the required refractive power, thereby reducing thickness.

The patent optimizes the curvature radii and refractive powers of multiple lens surfaces within controlled parameter ranges. By distributing the power requirements across multiple surfaces with optimized parameters rather than one surface with extreme curvature, the system achieves the necessary refractive power while maintaining reduced thickness through balanced parameter selection.