Optical system

An optical system, comprising:

• a first optical stack, the first optical stack comprising:
• a first optical lens;
• and
• a partial reflector having an average optical reflectance of at least 30% in a desired plurality of wavelengths;
• and
• a second optical stack disposed adjacent to the first optical stack and convex along orthogonal first and second axes, the second optical stack comprising:
• a second optical lens;
• a reflective polarizer substantially transmitting light having a first polarization state and substantially reflecting light having an orthogonal second polarization state, at least one first location on the reflective polarizer having a radial distance r1 from an optical axis of the second optical stack and a displacement s1 from a plane perpendicular to the optical axis at an apex of the reflective polarizer, s1/r1 being at least 0.1;
• and
• a first quarter wave retarder disposed between the second optical stack and the first optical stack,
• wherein the optical system is adapted to provide an adjustable dioptric correction.