Tunable cylindrical lenses and head-mounted display including the same

A head-mounted display system, comprising:

• a first optical element comprising a first refractive element arranged along an optical axis, the first refractive element having a first variable cylinder refractive power and a first cylinder axis along a first radial direction orthogonal to the optical axis;
• a second optical element comprising a second refractive element arranged along the optical axis, the second refractive element having a second variable cylinder refractive power and a second cylinder axis along a second radial direction orthogonal to the optical axis;
• a third optical element comprising a third refractive element arranged along the optical axis, the third refractive element having a third variable cylinder refractive power and a third cylinder axis along a third radial direction orthogonal to the optical axis, wherein the first, second, and third radial directions are different;
• and
• an electronic controller configured to control the first, the second, and the third variable cylinder refractive powers, to form an optical element comprising the first, second, and third refractive elements and having an overall spherical refractive power (SPH), cylinder refractive power (CYL), and cylinder axis (Axis) according to a prescription (Rx).