Polarization based dual imaging optical system
Aspects of the disclosure provide an optical system. The optical system includes a polarization controller that controls polarization states of light beams such that a polarization state of each light beam passing through the polarization controller has one of a first polarization state and a second polarization state. The optical system includes a beam splitter, a reflective polarizer, and one or more lenses between the beam splitter and the reflective polarizer. If a polarization state of a first light beam of the light beams that passes through the polarization controller has the first polarization state, the first light beam passes the one or more lenses only one time. If a polarization state of a second light beam of the light beams that passes through the polarization controller has the second polarization state, the second light beam passes the one or more lenses more than one time.
1. An optical system, comprising:
a polarization controller configured to control polarization states of light beams incident onto the polarization controller such that a polarization state of each light beam passing through the polarization controller has one of a first polarization state and a second polarization state;
a beam splitter configured to partially transmit and partially reflect the light beams incident onto the beam splitter;
a reflective polarizer configured to pass the light beams having a third polarization state and reflect the light beams having a fourth polarization state that is orthogonal to the third polarization state; and
one or more lenses between the beam splitter and the reflective polarizer, wherein
in response to a polarization state of a first light beam of the light beams that passes through the polarization controller having the first polarization state, the first light beam passes the one or more lenses only one time, and
in response to a polarization state of a second light beam of the light beams that passes through the polarization controller having the second polarization state, the second light beam passes the one or more lenses more than one time.
2. The optical system according to claim 1 , wherein
the polarization state of the first light beam that passes through the polarization controller has the first polarization state,
the first light beam passes the one or more lenses only one time, and
a first focal length of the one or more lenses for the first light beam in the first polarization state is different from a second focal length of the one or more lenses for the second light beam in the second polarization state.
3. The optical system according to claim 1 , wherein
the polarization state of the second light beam that passes the polarization controller has the second polarization state, and
the second light beam passes the one or more lenses more than one time.
4. The optical system according to claim 3 , wherein
an optical cavity including the one or more lenses is formed between the beam splitter and the reflective polarizer, and
the second light beam passes the optical cavity three times before reaching a viewing position.
5. The optical system according to claim 1 , further comprising:
a quarter waveplate (QWP) that is positioned between the beam splitter and the reflective polarizer.
6. The optical system according to claim 5 , wherein
the optical system further includes a first lens,
the one or more lenses includes a second lens,
the second lens is positioned between the first lens and a display device, and
the first lens is positioned between the second lens and a viewing position.
7. The optical system according to claim 6 , wherein
the first lens and the second lens are separated by a gap.
8. The optical system according to claim 6 , wherein
one of the first lens and the second lens includes a Fresnel structure.
9. The optical system according to claim 6 , wherein
the beam splitter is positioned between the second lens and the display device,
the reflective polarizer is positioned between the first lens and the second lens, and
the QWP is positioned between the beam splitter and the reflective polarizer.
10. The optical system according to claim 1 , wherein
the first light beam passes the polarization controller at a first time point,
the optical system has a first focal length at the first time point,
the second light beam passes the polarization controller at a second time point that is different from the first time point, and
the optical system has a second focal length at the second time point, the second focal length being different from the first focal length.
11. The optical system according to claim 10 , wherein
the optical system forms, at the first time point, a first virtual image of a first object located at a distance from the optical system, the first virtual image being perceived at a first distance from a viewing position, a first magnification being a ratio of a size of the first virtual image over a size of the first object,
the optical system forms, at the second time point, a second virtual image of a second object located at the distance from the optical system, the second virtual image being perceived at a second distance from the viewing position, the second distance being different from the first distance, a second magnification being a ratio of a size of the second virtual image over a size of the second object, and
the second magnification is different from the first magnification.
12. The optical system according to claim 11 , wherein
the first distance is a multiple of the second distance.
13. The optical system according to claim 11 , wherein
an image is formed based on the first virtual image and the second virtual image.
14. The optical system according to claim 1 , wherein
the first light beam passes a first region of the polarization controller,
the optical system has a first focal length for the first light beam passing the first region of the polarization controller,
the second light beam passes a second region of the polarization controller that is different from the first region, and
the optical system has a second focal length for the second light beam passing the second region of the polarization controller, the second focal length being different from the first focal length.
15. The optical system according to claim 14 , wherein
the optical system forms a first virtual image of a first object located at a distance from the optical system, the first light beam from the first object passing the first region of the polarization controller, the first virtual image being perceived at a first distance from a viewing position, and
the optical system forms a second virtual image of a second object located at the distance from the optical system, the second light beam from the second object passing the second region of the polarization controller, the second virtual image being perceived at a second distance from the viewing position, the second distance being different from the first distance.
16. The optical system according to claim 15 , wherein
a first magnification is a ratio of a size of the first virtual image over a size of the first object,
a second magnification is a ratio of a size of the second virtual image over a size of the second object, and
the second magnification is different from the first magnification.
17. The optical system according to claim 15 , wherein
an image is formed based on the first virtual image and the second virtual image.