Free-form prism-lens group and near-eye display apparatus

A free-form prism-lens group, comprising:

• a primary prism, a first auxiliary lens, and a second auxiliary lens;
• wherein:
• the primary prism has a plurality of surfaces including only three optical surfaces;
• a first optical surface is configured as an incident surface facing a micro-display device for receiving an image light from the micro-display device, and transmitting the image light into the primary prism;
• a second optical surface is configured as an exit surface;
• a third optical surface is configured to reflect the image light back into the primary prism once during a process of the image light propagated from the first optical surface to the second optical surface and exiting from the primary prism;
• the first optical surface, the second optical surface, and the third optical surface are free-form surfaces;
• the first auxiliary lens is arranged adjacent to the primary prism and is not configured for imaging of the image light;
• the second auxiliary lens is arranged adjacent to the primary prism and a gap with a predetermined thickness is arranged between the second auxiliary lens and the primary prism, and the adjacent surfaces of the primary prism and the second auxiliary lens have consistent free-form surfaces to satisfy the condition of total internal reflection of the image light when the image light reaches the second optical surface for a first time;
• the second auxiliary lens extends in a direction perpendicular to an optical axis to cover an effective aperture of the image light entering the second auxiliary lens from the primary prism;
• and
• the primary prism has extended edge portions disposed symmetrically about a vertical plane passing through the optical axis and extending from the first optical surface and the third optical surface, respectively, such that the freeform prism-lens group has a size not limited by the micro-display device, the extended edge portions have non-free-form surfaces and are not configured as optical surfaces for imaging of the image light while having smooth transitions with the first optical surface and the third optical surface, respectively.