Visual system

A visual system, comprising, in order from a first side to a second side along an optical axis:

• a first lens having a positive refractive power, with a first side surface being convex;
• a reflective polarizing element;
• a quarter-wave plate;
• a second lens having a positive refractive power or a negative refractive power;
• a third lens having a positive refractive, with a second side surface being convex;
• and
• a partially reflective element,
• wherein the third lens is configured to be able to move along the optical axis to approach or move away from a display located on the second side, so that the visual system switches between a first state and a second state;
• and
• the visual system satisfies:
• 0.05
• <
• f
• ⁢
• 3
• /
• fz
• <
• 2.35
• ;
• 1.28
• ≤
• f
• ⁢
• 3
• /
• (
• fm
• +
• fn
• )
• ≤
• 4.85
• ;
• and
• 0.19
• ≤
• Δ
• ⁢
• L
• /
• CT
• ⁢
• 3
• ≤
• 0
• .86
• ;
• where f3 is an effective focal length of the third lens, fz is a combined focal length of the first lens, the reflective polarizing element, the quarter-wave plate, and the second lens, fm is an effective focal length of the visual system in the first state, fn is the effective focal length of the visual system in the second state, ΔL is a distance by which the third lens moves along the optical axis in a process of the visual system switching from the first state to the second state, and CT3 is a center thickness of the third lens on the optical axis.