Delection Lens and Detection Method for a Head-Mounted Display

A detection lens for a head-mounted display, wherein,

• the detection lens is provided with a light incident end, and is configured for receiving light from the light incident end;
• the detection lens comprises a lens group, and an overall entrance pupil of the lens group overlaps with an aperture stop of the lens group;
• the lens group comprises a first lens group and a second lens group, wherein
• the first lens group is closer to the light incident end relative to the second lens group along an axial direction of the detection lens,
• an effective focal length of the first lens group ranges from 20 mm to 40 mm,
• a magnification of the second lens group ranges from 0.5 to 2, and
• an effective focal length of the second lens group ranges from 195 mm to 285 mm;
• the second lens group comprises a double-Gauss lens group, wherein
• the double-Gauss lens group is located close to the light incident end in the second lens group, and
• a side of the double-Gauss lens group close to the light incident end is provided with at least three Gauss lenses which have positive focal powers;
• and
• the detection lens has a lateral angle of view of less than or equal to 120 degrees and a longitudinal angle of view of less than or equal to 80 degrees.