Catadioptric lens for near eye display
Aspects of the disclosure provide a first lens. The first lens can include an optically transparent member having a first surface and a second surface. The optically transparent member can be configured to receive light from a display device via the first surface. The received light exits the optically transparent member through the second surface. The first surface and the second surface of the optically transparent member can be aspheric. An in inner surface of the first surface is convex, and an outer surface of the first surface is concave. The inner surface is surrounded by the outer surface of the first surface. A thickness of a central region of the first lens can decrease from a center of the first lens, and a thickness of a peripheral region of the first lens can increase from a boundary of the central region.
1 . A first lens, comprising:
an optically transparent member having a first surface and a second surface, the optically transparent member being configured to receive light from a display device via the first surface, the received light exiting the optically transparent member through the second surface, wherein
the first surface and the second surface of the optically transparent member are aspheric,
an inner surface of the first surface is convex,
an outer surface of the first surface is concave, the inner surface being surrounded by the outer surface of the first surface,
a curve formed by an interception of the first surface of the first lens and a cross-sectional plane has at least four inflection points, the cross-sectional plane being parallel to an optical axis of the first lens, and
a plane that is perpendicular to the optical axis of the first lens intercepts the second surface of the first lens four times.
2 . The first lens according to claim 1 , wherein
a sagitta difference between (i) a minimum sagitta at a first position of the first surface of the first lens and (ii) a maximum sagitta at a second position of the first surface of the first lens is from 1.5 millimeters (mm) to 2.5 mm.
3 . The first lens according to claim 2 , wherein
a sagitta difference between (i) a minimum sagitta at a first position of the second surface of the first lens and (ii) a maximum sagitta at a second position of the second surface of the first lens is from 0.6 mm and 0.8 mm.
4 . A lens system comprising:
the first lens according to claim 1 , and
a second lens configured to direct the light from the display device to the first lens, the first lens being positioned between the second lens and a light receiver, the second lens being a converging lens.
5 . The lens system according to claim 4 , wherein
the first lens and the second lens are separated by a gap.
6 . An optical system, comprising:
the lens system according to claim 4 ,
a beam splitter configured to partially transmit and partially reflect light beams from the display device,
a reflective polarizer configured to pass through light having a first linear polarization state and reflect light having a second linear polarization state that is orthogonal to the first linear polarization state, and
a quarter waveplate (QWP) that is positioned between the beam splitter and the reflective polarizer, wherein
the optical axis of the first lens and an optical axis of the second lens are identical in the lens system,
the beam splitter is on a first surface of the second lens that is configured to face the display device, and
the reflective polarizer is on the second surface of the first lens.
7 . The optical system according to claim 6 , wherein
the QWP is on a surface of (i) the first lens or (ii) the second lens.
8 . The optical system according to claim 6 , wherein
the optical system includes the display device, a pixel array in the display device being configured to generate light beams, a polarization state of the light beams being a first circular polarization state,
an optical cavity is formed between the beam splitter and the reflective polarizer,
the optical cavity includes the first lens, the second lens, a gap between the first lens and the second lens, and the QWP,
the beam splitter partially transmits one of the light beams,
after the one of the light beams passes the optical cavity for a first time, the first circular polarization state of the one of the light beams being converted to the second linear polarization state by the QWP,
the reflective polarizer reflects the one of the light beams having the second linear polarization state,
after the one of the light beams passes the optical cavity for a second time, the one of the light beams is reflected by the beam splitter,
after the one of the light beams passes the optical cavity for a third time, the second linear polarization state of the one of the light beams is converted to the first linear polarization state by the QWP, and
the reflective polarizer transmits the one of the light beams having the first linear polarization state such that the one of the light beams is directed to the light receiver.
9 . The optical system according to claim 8 , wherein
the optical system is included in a head mounted display (HMD), and
a field of view of the optical system is larger than or equal to 90°, a distance between the light receiver and the first lens is 15±2 millimeters (mm), a lens track length that is a distance between the second lens and the display device is from 12 to 21 mm, and a diagonal size of a region in the display device that generates the light beams is from 1.4 inches to 2.6 inches.
10 . A first lens, comprising:
an optically transparent member having a first surface and a second surface, the optically transparent member being configured to receive light from a display device via the first surface, the received light exiting the optically transparent member through the second surface, wherein
the first surface and the second surface of the optically transparent member are aspheric,
a thickness of a central region of the first lens decreases from a center of the first lens,
a thickness of a peripheral region of the first lens increases from a boundary of the central region,
a curve formed by an interception of the first surface of the first lens and a cross-sectional plane has at least four inflection points, the cross-sectional plane being parallel to an optical axis of the first lens, and
a plane that is perpendicular to the optical axis of the first lens intercepts the second surface of the first lens four times.
11 . The first lens according to claim 10 , wherein
a sagitta difference between (i) a minimum sagitta at a first position of the first surface of the first lens and (ii) a maximum sagitta at a second position of the first surface of the first lens is from 1.5 millimeters (mm) to 2.5 mm.
12 . The first lens according to claim 11 , wherein
a sagitta difference between (i) a minimum sagitta at a first position of the second surface of the first lens and (ii) a maximum sagitta at a second position of the second surface of the first lens is from 0.6 mm and 0.8 mm.
13 . A lens system comprising:
the first lens according to claim 10 , and
a second lens configured to direct the light from the display device to the first lens, the first lens being positioned between the second lens and a light receiver, the second lens being a converging lens.
14 . The lens system according to claim 13 , wherein
the first lens and the second lens are separated by a gap.
15 . An optical system, comprising:
the lens system according to claim 13 ,
a beam splitter configured to partially transmit and partially reflect light beams from the display device,
a reflective polarizer configured to pass through light having a first linear polarization state and reflect light having a second linear polarization state that is orthogonal to the first linear polarization state, and
a quarter waveplate (QWP) that is positioned between the beam splitter and the reflective polarizer, wherein
the optical axis of the first lens and an optical axis of the second lens are identical in the lens system,
the beam splitter is on a first surface of the second lens that is configured to face the display device, and
the reflective polarizer is on the second surface of the first lens.
16 . The optical system according to claim 15 , wherein
the optical system is included in a head mounted display (HMD), and
a field of view of the optical system is larger than or equal to 90°, a distance between the light receiver and the first lens is 15±2 millimeters (mm), a lens track length that is a distance between the second lens and the display device is from 12 to 21 mm, and a diagonal size of a region in the display device that generates the light beams is from 1.4 inches to 2.6 inches.